“battery for scooter -bike battery power”

Cool project! I’d check out electric rider (www.electricrider.com) as I know they have some good electric rickshaw and electric tricycle kits. You’re looking for a strong 48V motor that is geared really low. You want torque, not speed. With slow speed, something in the 1,000 – 1,500W is probably enough. Just don’t expect to be flying down the road…

RC packs may be fine for enthusiasts that know what they’re doing, but even telling others about them scares me! FIRE! And secondly, they typically don’t have any BMS so don’t have any inherent protection from over-under voltage or balancing. FIRE!

Lithium Polymer is by far the lightest battery option out there. LiPoly cells that can handle very high discharge currents are becoming widely available and are especially popular in the R/C crowd for electric airplanes and helicopters, but ebike LiPoly packs are often made with cells that are only rated to 1C or 2C, and these don’t usually deliver a very good cycle life count. The cells are produced in a thin plastic pouch rather than a metal can, making them structurally quite vulnerable unless supplied with a rigid enclosure. Although Lithium Polymer has a reputation for being volatile and failing with spectacular pyrotechnics, there are companies making cells these days that are quite stable and can pass the fullUN 38.3 overcharging and puncture tests without any flames.

Yes, I’ve seen this problem. Homes that have only a 10A circuit breaker are often not enough for these welders. The room I wanted to use mine in had a 10A, so I switched it for a 20A breaker at the breaker box and now it works fine.

The spacers you linked to make battery building a bit easier as you can set it up modularly, but as you indicated, they add a good amount of volume to the battery. I like to make my batteries as small as possible so I rarely use them. When I do, I use these ones, but it’s not very often.

HERE ARE 99 GENIUNE LG LGABB41865 18650 2600MAH CELLS. THEY ARE IN MODEM BATTERIES, JUST NEED A FLAT SCREW DRIVER AND PRY THE CASE AT THE SEAM. THEY ARE IN 12V (3S1P) SET UP ALREADY SO YOU CAN SAVE A …

Author’s note: Hi guys, Micah here. I run this site and wrote this article. I just wanted to let you know real quick about my new book, “DIY Lithium Batteries: How To Build Your Own Battery Packs” which is available in both ebook and paperback format on Amazon and is available in most countries. It goes into much deeper detail than this article and has dozens of drawings and illustrations showing you every step of designing and building a battery. If you find this free site helpful, then taking a look at my book can help support the work I do here to benefit everyone. Thanks! Ok, now back to the article.

I’ve been reading a bit about how Batterybro.com makes sure to test there batteries are genuine, and how it seems they still get a lot of fake batteries from China. When you buy on Aliexpress.com how to you know and make sure the batteries you buy are genuine? there’s a lot of sellers how did you find yours?

One of the easiest ways to increase the current handling capability and range is to put two or more batteries in parallel. In general, with lithium batteries of the same nominal voltage, this is no problem. It is perfectly fine to mix old and new lithium batteries in parallel, or even batteries from different manufacturers and with different capacities, so long as they are the same voltage. We stock a parallel battery joining cable to facilitate connecting packs this way. 

There is some research into 18650 packs that use pressure connectors like in a remote control but most results aren’t impressive yet. It’s difficult to get a good enough connection to deliver high enough power for ebike applications. The ones that are close to working use custom designed enclosures. Don’t attempt to do it with off-the-shelf 18650 holders with spring contacts — you’ll melt them in no time.

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My series connections are between each group of 3 parallel cells. So all the connections that go across the short side of the pack are parallel connections, and all the connections that run along the long end of the pack are series. It doesn’t always happen that way, but the shape of this pack forced that geometry.

I was wondering, though, if I could use thick gauge wire instead of nickel strips (copper wires are much more accessible). Would there be any downsides to that, given that I’m going to be using solder anyway?

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You can buy LiFePO4 straight from China from Ping Battery. These batteries are a little bulky, but are safe, and will last over 1000 charges. You can also buy ready made Lithium Iron Phoshate (LiFePO4) or Lithium Polymer (LiPo) packs from BMS battery.

The 48V, 8AH lithium battery of this ebike is removable. Material: Aluminium alloy frame. E-bike & Assisted bicycle, you can choose the E-bike to enjoy a long time travel, and also exercise. Combining…

Next, grab another 3 cells (or however many you are putting in your parallel groups) and perform the same operation to make another parallel group just like the first one. Then keep going. I’m making eight more parallel groups for a total of 10 parallel groups.

A big downside of lithium batteries is that they are much more expensive than lead acid batteries. Prices vary depending on the voltage and capacity of the lithium battery, but standard ebikes usually have lithium batteries starting in the $300 range and rising quickly from there. Most bikes I build have lithium batteries in the $400-$500 range.

To answer your question, you can definitely build your own auxiliary battery. It looks like they used a fancy right angled female XLR connector, but I imagine a standard female XLR connector will fit just as well. I’m not sure if you’ll be voiding your warranty though by connecting your own battery. Those XLR connectors can be purchased all over ebay and probably even at your local electronics shop.

Bigger is better! And I know a better way batteries should be made. I use 560 of the Panasonic 18650b battery cells with 3.4AH per cell, wich in the end gave me (7kwh battery ebike!), that’s more than 300+ miles battery range easy. And I’ve learned that these batteries can be assembled like Lego blocks instead and eliminate harmful heat from soldiering, and wastful glueing. The benefit is a battery pack that can have removable, repairable, and reconfigurable battery cells! Its called (battery blocs) patiented by Shawn McCarthy. Unfortunatly its not the cheap method and requires a 3d printer to make. It spaces the cells slightly apart for better air cooling. Mine are packed into 4 PVC tubes run either at 103.6v or 51.8v. I believe along with some experts that a BMS is not required and can cause battery cells to fail early!, and a proper set voltage monitor and regulator prevents over discharge damage and you need to a timer and monitor the cell voltages with cell monitors while charging. Cooling setup would be a pluse to extend life. That’s all for now, best luck to all battery builders.

One question regarding the specific battery BMS you used in this build: It uses a different wire for charging vs discharging the battery. Does this mean that the regenerative braking feature cannot be used for this battery?

Thanks again for the great info, that is really helpful. I just have one last question. On the XLR connections there is a hot, neutral and ground. It appears on the battery you linked to that there are just two wires, how can I ensure which prongs of the male XLR connection on the Porteur are hot and negative? Also, do I just leave the ground spot on the female XLR connection open since there is just a hot and negative wire?

The article was extremely informative, thank you. I’ve found everything but am struggling with good cells. At Aliexpress there are many choices but I’m struggling to get near the $2/cell mark you mentioned as a limit for decent cells and still find performance criteria of a good battery (or at all). So far I’ve found NCR18650B but it appears to have a 2C discharge rating for a 3400mA cell. At 4P this is more than enough but seems low for LiIon so I wonder if it is good? The price is $163 shipped to USA for 10s 4p 40 pieces to make 36v 13.6Ah. After adding shrink wrap, BMS and nickle strips I’m at $213 before buying a spot welder ($200). I can buy on the same site a 36v 15Ah Li Ion pack for $248. https://www.aliexpress.com/item/US-EU-No-Tax-DIY-lithium-18650-battery-pack-15AH-36V-Electric-Bike-battery-for-36V/32757165516.html?spm=2114.13010208.99999999.274.JmcpBS

Spot welders for batteries aren’t the same as most home spot welders. Unlike the large jaw spot welders for home workshops, battery spot welders have the electrodes on the same side. I’ve never seen them for sale in the US, but they can be found pretty easily on eBay and other international commerce websites. My full time use welder is a fairly simple model that I got here. A highly recommended source for a slightly nicer spot welder design (pictured below) with both mounted and handheld electrodes can be found here.

While it is possible to build packs with any number of cells for just about any voltage, most have standardized in 12V increments, with 24V, 36V, and 48V being most common, and 72V used on occasion. Battery chargers are usually only stocked for these voltages as well.

All the help and knowledge I’ve provided here on EbikeSchool.com is 100% free, and I try to assist readers as much as possible in the comments section of each article. If you want to support this site and help me keep it free (and ad free), consider checking out my ebook and video course on building ebikes.

A 48 volt 20-Ah pack  contains 960 watt hours and once you get close to 1000 watt hours you are getting serious commuting range which most e-bike manufacturers promise but do not deliver…think 30 miles.

I am not sure their interests align with mine. I would happily live with 1500 recharge cycles () by which time i would be sick of it anyway) instead of 2000 if I could use 3c in or out when urgently needed.

This is our smallest battery offering specifically aimed at people who have to travel or fly with their ebike. Each module is 36V 2.7Ah, so just under 100 watt-hours, exempting it from most of the heavy shipping restrictions. You can parallel connect them for as much capacity as required, and series connect them for 72V setups. Designed and made in Canada by Grin Tech, full details here.

For people who are new to the hobby, ready-made lithium packs are the way to go. Several manufacturers offer ready to go Lithium packs with a built in Battery Management System (BMS) at affordable prices.

Work in a clean area free of clutter. When you have exposed contacts of many battery cells all wired together, the last thing you want is to accidentally lay the battery down on a screwdriver or other metallic object. I once nearly spilled a box of paperclips on the top of an exposed battery pack while trying to move it out of the way. I can only imagine the fireworks show that would have caused.

I have built a few 13s lithium batteries in the past year following your instructions. Thanks. I have taken one of the batteries apart to check its condition as it is the middle of winter here in Winnipeg, Canada. Two parallel sets were out of balance with the rest of the pack. I was wondering if there is a way to use my imax b6 balance chargers to rewire the battery and keep each parallel pack in balance for sure! This way I will bypass the bms. Does this make sense?

“36v battery pack panasonic 18650 cells”

I want to use my two 4Ah Ryobi lithium batteries 18volts in series for 36 volts. I have a charger for them , they use 15 batteries each so 30 total, they are $50 each. This seems similar to your 36v build for about $3 each so $90 total, plus a spot welder for $1oo. I want to get a 38v/750 48v/1000w rear motor recommended from your web site from aliexpress. Do you think that these will work for my bicycle?

I have a homemade battery made up of 84 NCR18650b cells that I bought (in other words, I didn’t make the battery myself). Anyway, I lost the charger for it at Burning Man, and now I’m going nuts trying to figure out what kind of charger to buy. The arrangement of the batteries is odd. Part of the battery looks pretty straight forward in what I believe is a 8s6p design, but the rest look different… they are set up like a 4×3 rectangle framed by 2 L’s. I would have happily uploaded a picture, but that doesn’t seem possible. Is there anyway I can send you a picture to show you what I mean?

The single best manufacturer is BesTechPower, but their BMS’s are really expensive and they have a minimum order quantity of 2. For ‘best bang for your buck’ BMS’s I’d recommend Greentime BMS’s. They are great for most ebike applications outside of serious hotrods and speed machines. I use them on most of my packs.

Assuming the original battery is a li-ion battery and has the same number of cells in series (same voltage), then yes it should charge it. However, looking at the picture of the battery in that listing, I can tell you that is not a picture a 24V 25AH battery. That picture has 6 cells, and a 24V 25AH battery will have something more like 56 cells. That picture looks like a 22V 3AH battery. It could be that they simply used the wrong picture in the listing, though I doubt it as that would be an insanely good price for that size of a battery. but I’d be wary of that offer either way.

Nominal capacity: 12Ah (Fully charged after 0.5C discharge to 38V capacity). Cycle life: Standard charge and fast discharge cycle 500 times, the capacity will notless than 60% of the nominal capacity.

You’re absolutely right that doubling the capacity of the battery by running two packs in parallel will essential halve the load on each pack, but I still don’t think it would get it down to the level that you could rely on compression fit spring contacts to safely carry that current, let alone the balance issue of not having the 4 groups individually paralleled at the cell level.

I KNOW ALL YOU “DO-IT-YOURSELF” E-BIKE AND POWERWALL BUILDERS OUT THERE ARE LOOKING FOR AFFORDABLE AND HIGH QUALITY 18650 CELLS. HIGH DRAIN MEANING THESE ARE RATED FOR 10A CONTINUOUS AND 20A MAX PER C…

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I placed the first parallel group positive side up, and the http://electricbikebatterycharger.com parallel group negative side up. I laid the nickel strips on top of each of the three sets of cells, bridging the positive caps of the first parallel group with the negative terminal of the second parallel group, as shown in the picture.

Now that we’ve got all that pesky planning out of the way, let’s get started on the actual battery. Our work space is clear, all our tools are on hand, we’ve got our safety equipment on and we’re ready to go. We’ll begin by preparing our individual 18650 battery cells.

We also maintain stock of replacement vertical seattube batteries that have been in use in the eZee bicycle line since time immemorial. If you have an eZee bike circa 2008-2012 with the Phylion lithium battery pack, you’ll be in for a serious upgrade with over twice the capacity in the same size and weight.

How do you determine this exactly? Your battery is a 36v 8.7Ah and I guess it has something to do with the maximum continuous discharge rate. It would help me (and maybe others) to explain why 30A is more than enough for this battery.

Battery chargers for electric bike batteries need to be specific for that voltage and type of battery. Lead batteries need a charger that trickle charges when finished, while lithium battery chargers do not trickle charge. E-Bikekit batteries are sold with the correct charger that matches the voltage and type for that battery.

When it comes to nickel strip, I also like to use Aliexpress. You can also find it on ebay or even a local source if you’re lucky. Once I started building lots of batteries I began buying pure nickel strip by the kilogram here, but in the beginning I recommend you pick up a smaller amount. You can get pure nickel strip for a good price in smaller amounts from a seller like this one, but you’ll still get the best price by buying it in kilo or half kilo quanitites.

Lithium batteries (with the exception of RC LiPos) last much longer than lead acid batteries. LiPo batteries are usually only rated for a few hundred charge cycles but LiFePO4 batteries keep going after thousands of charge cycles. Every manufacturer rates their batteries differently, but most LiFePO4 ebike batteries will be rated for between 1,500 to 2,200 charge cycles.

For any other case, lithium batteries’ advantages greatly outweigh SLAs. Of course, for your specific ebike you might have other reasons that could sway you either way. At the end of the day, your ebike is all about you. I hope this information helps you make the right choice for your own battery needs.

I’m deeply uncomfortable with recommending RC LiPo from the likes of Turnigy for people who don’t know what they’re doing. The above 3 options are plug and play and require no special skills. And they’re essentially safe when bulk charged with the associated charger.

If you want to go 50mph and have a 500 or 1,000-watt monster motor on your electric bike you’ll need big expensive, heavy batteries, and you might as well buy a motor scooter or motorcycle. If you wan…

With a budget in mind, here is a 36V charger (output 42V, exactly what a 36V li-ion pack needs) that I have used and found to be a good budget charger. It’s not super fast, at only 2A, but for just $20 shipped, it’s a great deal. You might have to wait about 3 weeks for it arrive from China though. http://www.aliexpress.com/item/100-240VAC-42VDC-2-0A-Lithium-LiPo-Battery-Charger-E-Bike-charger-suitable-for-10S-36V/559929087.html

Secondly, what is your take on modular plastic battery spacers (e.g. http://www.ebay.co.uk/itm/50x-EV-Pack-Plastic-Heat-Holder-Bracket-Battery-Spacer-18650-Radiating-Shell-New/351681365193?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36381%26meid%3Dfc487881e617412ba361731154a742b5%26pid%3D100005%26rk%3D5%26rkt%3D6%26sd%3D262123820960). Clearly this adds a significant volume penalty and a smaller weight / cost one, but if this is not an issue then how would you rate vs glueing? I can see the benefit of having a space between the cells to limit heat / electrical conductivity in the event of some kind of melt down, but any thoughts?

Next, plan out your cell configuration on your computer or even with a pencil and paper. This will help ensure you are laying out your pack correctly and show you the final dimensions of the pack. In my top-down drawing below I’ve designated the positive end of the cells in red and the negative end of the cells in white.

For a complete write up on LiFePO4 care and trouble shooting read our story here. LiFePO4 cells nominal voltage is generally from 3.0-to 3.2 volts, and generally, lifepo4 is a heavier and less power dense than available LiPo batteries and is not capable of as high of amperage discharge.

Also I wanted to “hide” the batteries in the Brompton frame aligning the batteries in file, I understand it would not have a long range but would be quite stealthy. If you have any recommendations please do tell me

I’m wondering, what do you do for 6V or 12V applications where the correct number of in-series cells is ambiguous? For example, if I’m replacing a 6V SLA battery, it seems like the existing charging system would set a 1s battery on fire, but wouldn’t be sufficient to charge a 2s battery. Are there BMS’s that have VRs to step up the voltage from the charging system to the battery, and step down voltage from the battery to the charging system to facilitate a 2s battery for the application?

26\” wheels with Aluminum Alloy spokes. Opportunity: Outdoor Camping, Mountain. Speed up to 25km/h,High speed brushless shock. 36V 8AH Lithium-Ion Battery. Material: Aluminum Alloy. Mileage range: ≥40…

“scooter battery 48v _battery bike”

Dang, I just realized what I did wrong. I had been thinking as I connected the sense lines it was arbitrary which end of the battery was B1 and which B13, but obviously it isn’t. B1 has to be the negative end and B13 has to be the positive end. Since I already cut the sense lines to length, I’ll need to put my replacement BMS on the opposite end of the pack.

What I would recommend doing is trying to ride again and when the battery cuts off, take it inside and measure the voltage of each parallel group before you try recharging it. Measure straight on the battery. If you find one group that is lower than the rest, it is likely the problem. It might have risen back up to a reasonable voltage with no load, but it can still be lower than the rest.

LiPo packs that are homebuilt (without a BMS) can be extremely dangerous if you do not approach your battery with a lot of knowledge and care. Be sure to research extensively before building such a pack. Many E-bikers construct packs with no BMS using Turnigy/Zippy packs, acquired cheaply online through the Hobby King company which is based in China.  For those who risk running their batteries without BMS they still use sophisticated chargers to balance their packs and constantly monitor the health of their cells.

Hi Micah, thank you for your advice. I am not going to touch that battery. I know this may be a lot to ask, but would you build me a battery for my velomini 1 ? It doesn’t have to be the one that fits in the frame, I could put it in a bag and hang it on the handlebars or something. If more convenient you can email me directly at dlimjr at yahoo. My sincere thanks and may you and your family have a happy holiday.. Don, San Francisco

NiMH-Nickel Metal Hydride. This was the battery of choice for military application and the first-gen Prius hybrid car. Very reliable and stable, with a long cycle life. It has a high nickel content, so its expensive now (but the nickel can be re-cycled). With a low C-rate, you need a very big battery to draw high peak amps. Perhaps not a problem on a car with its huge battery pack, but on a bicycle, the smaller pack restricts the user to low amp-draw performance.

Once I’ve got all the cells I need checked out and ensured they have matching voltages, I like to arrange them on my work surface in the orientation of the intended pack. This gives me one final check to make sure the orientation will work as planned, and a chance to see the real-life size of the pack, minus a little bit of padding and heat shrink wrap.

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It is possible to do it that way, however there are some compelling reasons not to. 1) By first joining all the series cells you would end up with multiple high voltage groups, which means both the chance and consequences of an accident are greater. When you’re working with lots of exposed batteries with nickel conductors and metal tools flying around, the last thing you want is more high voltage possibilities for shorts. 2) Doing series cells first would be come unwieldy, physically. A series group is only connected at either the top or bottom of alternating cells. Without having multiple cells side by side to add stability, a long chain of single cells will need either a pile of glue or some type of physical holder to support the chain. and 3) most battery spot welders can only reach about 2 cells deep into a pack, meaning you’d have to either add very short nickel strips to each series group connecting only two groups (which means twice the welding and twice the cell damaging heat) or have long uncontrolled nickel strips hanging off the sides, again risking shorting.

A higher voltage setup therefore needs fewer amp-hours to deliver the same range. So a 24V 8Ah battery can deliver 192 watt-hours, while a 48V 4Ah pack also has 192 watt-hours. Assuming that both batteries are of the same chemistry, then you could expect they would weigh the same, cost the same, and provide the same performance on appropriately designed ebikes (ie, one designed for 24V and the other for 48V).

You too can find a metal box to store your batteries in while riding and charging.  Here is an example of a custom built metal box that holds six hobby king packs perfectly (make certain to add a vent so pressure does not build up if a pack goes into flames!):

The chain is a very important bicycle part. It is responsible for turning the wheel when a cyclist pedals the bike. Problems with the chain create major riding problems. Chains commonly get dry or rusty,…

I have an old 12V DC Brush Motor which its consumption is around the 12A, 13 A and I built a Battery pack, with two groups of batteries, (4S6P)+(4S6P), which makes a total pack with 14,8V 30A. To make this battery pack I used 18650 Samsung Cells 2600 mAh.

$Xport 350W 7 Speed Electric Bike Features: 350W motor, Samsung Lithium Battery 3 Riding Modes: Electric (Throttle, 3 speed), Electric with Pedal, Pedal Only Spec: Motor: 350W Battery: 24V Samsung Lit…

If you have some wire scrap left from any other project you could use them to lengthen the sense wires to your BMS and not need to relocate the BMS. Very little current travels through the sense wires so you can use very small diameter wire. Even the wire from an old USB cable would work.

Yes, you can upgrade a GIO PB710 with a lithium battery. You just want to make sure your battery is the same voltage as the original lead acid battery and that it can handle the current demanded by the bike’s controller.

Assuming the original battery is a li-ion battery and has the same number of cells in series (same voltage), then yes it should charge it. However, looking at the picture of the battery in that listing, I can tell you that is not a picture a 24V 25AH battery. That picture has 6 cells, and a 24V 25AH battery will have something more like 56 cells. That picture looks like a 22V 3AH battery. It could be that they simply used the wrong picture in the listing, though I doubt it as that would be an insanely good price for that size of a battery. but I’d be wary of that offer either way.

You’ve done your math correctly, though that “1000W” figure is largely arbitrary, and probably not the exact power level of the kit. Most 1000W kits I’ve seen use controllers in the 20-25A range, but it can vary greatly.

1C charging is too high for most Li-ion. It’s too much to ask for right now, to be able to charge an entire pack in one hour. It can be done, but it’s not healthy for the cells. Aim for 0.5C at the most. I usually don’t go past 0.3C on charging.

NCA…LiNiCoAl / Lithium Nickel Cobalt Aluminum (sometimes called NCR) The battery chemistry research industry is still driven by the HUGE global sales of laptop computers, cellphones, and cordless tools. Mass production has made the 18650 format the best cost per volume cell. The 18650 number means that it is 18mm in diameter, 65mm long, and the zero means it is a cylinder instead of a flat foil packet. (the 18650 is roughly the size of an adult male thumb) [edit: in 2014, Tesla electric cars are now using Panasonic NCA batteries]

A recent quote from ES member SamTexas on claimed max C-rates: “…I have in front of me Samsung’s own Nickel (Manganese) 18650 cells….I have tested these cells at 3C continuous and they do deliver full capacity at that rate. Push it to 5C and they become hot and capacity is greatly reduced…“

These cells are distinctive due to their cylindrical shape and are about the size of a finger. Depending on the size of the battery you plan to build, you’ll need anywhere from a few dozen to a few hundred of them.

Good question. The answer comes down to the difference between “nominal voltage” and “actual voltage”. LiFePO4 cells are nominally called 3.2V cells, because this is their voltage in the middle of their discharge curve, at about 50% discharge. They actually charger to a higher voltage though, about 3.7V per cell. That means that you need a charger that has an output voltage of 3.7V x 6 cells = 22.2V DC. This is going to be a bit harder to find because most LiFePO4 packs come in multiples of 4 cells, (4, 8, 12, 16 cells, etc) so finding a charger for a 6S pack might take some searching. This charger is a good quality one meant for 8 cells (output voltage of 29.2V DC) but if you put a note in the purchase order, the seller can adjust the output for 6 LiFePO4 cells (22.2V DC). http://www.aliexpress.com/store/product/aluminum-shell-24V-29-2V-3Amper-Lifepo4-battery-charger-high-quality-charger-for-8S-lifepo4-battery/1680408_32274890691.html

Just completed the pipeline challenge 600km of grueling maintenance trail. plenty of sand, rocks pea gravel, some road stages. Running an 8T MAC in a 29ER with 2x 29E EM3ev triangle ebike battery packs (one borrowed from Kai in review above!) managed 99kms on a single charge using …

Some of the NMC sellers are advertising their chemistry as 5C, but real-world use by E-bike builders has them calling NMC a solid reliable 3C chemistry, which can provide a continuous 30A from an affordable and compact 10-Ah battery (temporary peak amp-draws can be higher, as it is with any of these chemistries). This may sound only as good as the most recent LiFePO4, but NMC is smaller, and is not as fussy about keeping the individual cells balanced.

When comparing between battery chemistries, one of the most relevant metrics is the Energy Density in watt-hrs / kg. This figure says how heavy a battery pack will have to be to achieve a certain range. For Lead Acid it is 20-30 whrs/kg, for NiCad it is 35-40 whrs/kg, NiMH is 50-60 whrs/kg, Li-ion is ~110 whrs/kg, and Li-Polymer is up to 160 whrs / kg. Knowing these values makes it easy to project the weight of a pack without having to look up data from the manufacturer.

Really nice article you made here. very helpful. I do have some questions about the BMS board you used. Would you know where I could find any type of schematic for it because im trying to see whether I can use more then one of those BMS boards on one pack

Yes, it’s technically possible, but sometimes it is easier said than done. If the cells are on the edge of your battery, it’s much easier to cut them out (by the nickel, not by cutting the actual cell!) and replace them. If they are sandwiched in the middle of your pack then you’ll have to do a lot more pack surgery to get in and replace them. But yes, it’s possible to just remove them and replace them with new, good cells of the same capacity.

In general, the size and cost of a cell will scale directly with its amp-hour capacity. To a first order, twice the amp-hours would mean twice the size, twice the weight, and twice the cost. In practice this deviates a little due to different packing densities and production scales, but it’s usually pretty close. For instance, the familiar ‘AA’ NiMH has about 2 Ah, a ‘C’ cell has 4 Ah, a ‘D’ cell is about 8Ah, the large ‘F’ cells are 12-13 Ah, and double-D cells http://electricbikemotor.net 18-19Ah.

This is 14 series 52V (58.8v full charge) lithium battery power protection board. Balanced, same port continuous 45A discharge. 1x 14S 45A Lithium Battery Protection Board. Step2:After confirm the wir…

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This had led me to believe that if there is too much load being exerted on the bike (i.e. the current being drawn from the battery is too high) then either the BMS or the controller trips and cuts out. However I am reluctant to believe that the BMS is causing the trouble as it has a 40A rating on it (this link shows the exact BMS) http://www.aliexpress.com/item/Electric-motor-car-13S-48V-40A-BMS-lithium-ion-battery-BMS-Used-for-48V-20Ah-30Ah/32484213150.html?spm=2114.13010608.0.62.evx6sX .

There is some research into 18650 packs that use pressure connectors like in a remote control but most results aren’t impressive yet. It’s difficult to get a good enough connection to deliver high enough power for ebike applications. The ones that are close to working use custom designed enclosures. Don’t attempt to do it with off-the-shelf 18650 holders with spring contacts — you’ll melt them in no time.

“scooter battery -e bike battery”

Also I wanted to “hide” the batteries in the Brompton frame aligning the batteries in file, I understand it would not have a long range but would be quite stealthy. If you have any recommendations please do tell me

hi i was considering adding a second set of batteries to my ebike in parallel to double the range but heared on a thread somewhere that this can damage/overload the controller which i suspect is a load of tosh but can anyone confirm/clarify this as i assumed the amp hour capacity was just that and the max amp output was just that, the maximum that can be drained at once, my understanding is it doesnt matter what amp hr the pack is as the amps drawn into the controller is governed by the demands of the motor which wont change if i have 2 packs connected.

The best method is to use a trusted vendor. They interact with the cell providers and are the best way to confirm whether cells are fake or not. It can be incredibly difficult to tell whether a cell is fake or not just by picking it up from the table. There are some giveaways like different printing on the wrapper, slightly different color, different stamp, different weight or different shell design, but all of those can be mimicked. That’s why I use only a handful of vendors that I’ve worked with continuously and who I know have always given me good quality cells. I had to go through some low quality ones until I found the sources I buy from now.

Yep, that explains it. I was going to say that it sounds either like a defective BMS or more likely a connection error. B1 is definitely the negative end. Also some BMS units have B1- and B1+, others just have B1+. If it has both, it will have X+1 sense wires, where X is the number of series cells in the pack.

It was an interesting project to say the least, particularly how to link the Ch- and the P- from the BMS taking its B- from the 7s negative termination to the positive of the 6s group, given that there are two routes (i.e. charging and discharging), so connecting both simultaneously would override the function of the BMS.

I say this because I am assuming that the wire from the motor that connects to the battery and receives power from the battery would be the same wire that provides power in reverse to the battery when regenerative breaking. With this particular BMS, would it require a different wire to do the regenerative braking?

If not possible, try charging them individually. Some of them might come back but others might be dead. The tricky thing is that they will likely not be able to deliver their full capacity anymore and the actual capacity will likely vary from cell to cell. Two year old cells at a very low voltage are quite a gamble.

NO Memory Effect to reduce the capacity over time, longer life, more eco-friendly 1.5V / 1200MAH – Same as regular AA battery For toys, game controller, wireless mouse, wireless keyboard, remote and so on SAFE & ECO & NON TOXIC – Approved by FCC CE & RoHS, the 1200mAH AA lithium batteries are guaranteed

The answer is that, unless you are seriously budget or weight constrained, this would probably be a bad battery investment. It might fit the bill initially for your commuting needs, but then it doesn’t really leave any reserve if you need to run some errands on the way home, or forget to charge it up one night etc. Even worse, as the battery ages over time the capacity drops. After a year your 8Ah battery is now only 7Ah, it’s only barely able to do your daily commute, and the next year when it is just 6Ah you now need to carry the charger with you and top it up at work every day.

If you are upgrading or replacing an existing battery pack, it is always safe to replace it with a battery that has the same nominal voltage. If you have an 36V ebike setup that is not from us, and are looking to ‘upgrade’ to a 48V/52V pack, more often than not you can do this without damaging the existing electronics. That is because most 36V motor controllers use 60V rated mosfets and 63V rated capacitors, and so even a fully charged 52V battery will not exceed these values.

Connections are made with solid Nickel strips, spot welder to each cell. Each cell and each series is tested before assembly. The BMS will prevent over charging and will balance the cells after a full…

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Most commercially available 36V packs are around 10Ah, meaning our pack will be just a bit smaller. We could have also gone with a 4p configuration giving us 11.6 Ah, which would have been a slightly bigger and more expensive pack. The final capacity is totally defined by your own needs. Bigger isn’t always better, especially if you’re fitting a battery into tight spaces.

“bicycle battery kit |battery bike”

When you buy a Hobby King pack, it will have a number of these large cell LiPo’s strung together like this 6 cell in-series (6S) pack. The big downsides of this pack is that it will only last you in best case maybe 300 charges and it is volatile, and susceptible to possible fire if not well managed and cared for.  When using cobalt-based LiPo, it is best to use some kind of BMS, and also you should charge it in a safe location.

Grew up in Los Angeles California, US Navy submarine mechanic from 1977-81/SanDiego. Hydraulic mechanic in the 1980’s/Los Angeles. Heavy equipment operator in the 1990’s/traveled to various locations. Dump truck driver in the 2000’s/SW Utah. Currently a water plant operator since 2010/NW Kansas

Thank you for the article! I am currently making a battery for an electronic skateboard, so I need the layout to be as thin as possible to allow ample room underneath the deck. Currently, I have 6 packs of 3 cells welded in parallel, and would eventually like to create a battery which is 9 cells long, 1 wide, and 2 high, for 18 in total (the two packs of nine would then be welded in series). I am wondering if I could be able to make 2 battery packs by welding 3 of my current 3 cell packs together in parallel to make a long, yet skinny pack, and then welding both packs of nine in series using the alternating system. Essentially, I would be creating a pack that would look like 3 of the ones you show above when making your first series connection. Let me know what you think, and thank you!

Recently the federal goverment has been cracking down on the shipping of lithium batteries. For the vendor, it means that they must have Hazardous Materials (hazmat) shipping and pay hazmat charges, and only can ship an officially tested hazmat-compliant battery. This adds considerably to the cost of lithium batteries, and makes it even harder to find an ebike dealer, who will sell you any lithium battery pack that they can affordably source.

And a final point is that a larger battery has a lower per cell stress during discharge, since the current is shared among more parallel cells. Cells that are cycled at high discharge curents (>1-2C) also exhibit lower cycle life than those cycled at low currents

Features: It is so light weight , easy to transport and to take it. It is eco-friendly and safe to use it. The battery holder is so stable and sturdy. Super powerful,safe and reliable. Suitable for bi…

Yes, that’d work, but I’d get an additional 7s battery so you have 20s total. Also, you should know that the older your original 48V battery is, the more time it will take your new 72V combined battery to balance, as the first 13 cells will likely have less capacity in comparison to the newer cells. I made a video recently showing how to do this upgrade that you’re talking about: https://www.youtube.com/watch?v=9KHo-T74IWA

Nakto/SPARK ebikes are certificated with CE, EN15194, TUV, EMC, RoHS,EPAC. High Speed Motor:it is 250Watt high performance brushless motor,powerful and fast, the Max speed can be easy to 20Mile/h, sui…

Hi I need help! I am building my own battery pack from old laptop batteries (18650’s). I bought the cheep $250 48v 1000w ebike conversion kit on ebay. I have many questions! It seems the perfect number of cells to connect in series are 13! This is a big problem for me because I am cheep and I already bought the Imax B6 battery balancer charger. I also bought 7x 6s balancer leads and 5x 4s leads. The Imax has a max charge voltage of 22.2v (so it sais in the manual), and a max balance of 6 cells at once. I also bought the parallel balance charging board. I don’t want to charge two or three packs at once to just have to turn around and charge one separately. So now I’m faced with the decision of making a 12 series battery or a 15 series battery (I will buy 5s leads in this case). The problem is with the 12 series battery the nominal voltage is only 43.2. Or a 15 series battery with a nominal voltage of 54. Which I’m pretty sure is a big no no because the controller is only meant to handle 48v within reason (13s max charge voltage of 53.3 and 12s 49.2 at 4.1 v per cell). But if I make it a 12s, running around most of the trip at 44v, will this drain the Amps faster because the motor wants 48v? I’m thinking no but just wanted some confirmation on that and if the controller can handle more volts. I could make a 15 series batter and just charge to 3.6 or 3.7 volts. Is this hard on the cells?

Now take your trip distance, multiply it by the appropriate watt-hours/km from the table above, and you’ll get the total minimum watt-hours required for the trip. Take the watt-hours you’ve estimated and divide it by the voltage, and you now have an estimate on the minimum amp-hours you’ll need from the pack.

Rang: 18-25km(36v 6ah). Motor: 36V 250W brushless. Battery: 36V4/6AH lithium battery. The eco-friendly bicycle is 100% electric and emissions free, saving both your wallet and the environment. New Out…

The purchase price is often a turnoff for many people, but in reality $200 for a good hobby-level spot welder isn’t bad. All together, the supplies for my first battery, including the cost of the tools like the spot welder, ending up costing me about the same as if I had bought a retail battery of equal performance. That meant that in the end I had a new battery and I considered all the tools as free. Since then I’ve used them to build countless more batteries and made some huge savings!

Connections are made with solid Nickel strips, spot welder to each cell. Each cell and each series is tested before assembly. The BMS will prevent over charging and will balance the cells after a full…

Nickel Metal Hydride is quite similar to Nickel Cadmium, but with a higher energy density and a safer environmental record when disposed of in landfills. This is the dominant rechargeable battery type in digital cameras and other consumer products that offer user replaceable cells.

26′ rear wheel 48v 1000w hub motor (powerful Motor with hall sensor ) Electric Bike Kit With or Without Battery. 26′ size REAR WHEEL 48V 1000W ELECTRIC BIKE KIT WITH or WITHOUT BATTERY. 48v 1000w brus…

Regarding you question, if I understand you correctly, it seems that your 18650 lithium battery will be smaller than the old NiCad battery, so you have extra room in the battery box that needs to be filled, correct? My recommendation is to use some type of fairly rigid foam to fill the space. It adds almost no weight and it also helps cushion the battery pack.

Wear safety goggles. Seriously. Don’t skip this one. During the process of spot welding it is not at all uncommon for sparks to fly. Skip the safety glasses and head for chemistry lab style goggles if you have them – you’ll want the wrap around protection when the sparks start bouncing. You’ve only got two eyes; protect them. I’d rather lose an arm than an eye. Oh, speaking of arms, I’d recommend long sleeves. Those sparks hurt when they come to rest on your wrists and forearms.

36V10Ah Li-Ion NiCoMn “Little Frog” ABS shell ebike battery pack. Included 2p10s 5Ah polymer cells, 1pcs 15A continuous discharge current BMS, 1pcs 36V2.5Amps EMC-120 Lithium Ion battery Alloy shell charger.

You may have read recently about the “Bad Girl” of battery chemistries. Its rediculously high C-rate of 20C minimum (you can actually find them with a higher C-rate than this!) means that this is the battery of choice for Electric racers. A proper charging system is expensive, but the batteries themselves were surprisingly cheap when sourced directly from China. What’s the bad part? On rare occasions, they might…CATCH ON FIRE!? 

Another excellent answer, thanks so much! Now it has arisen a few related questions, if you don’t mind answering them. I’m using authentic Samsung ICR18650-26FM cells. I had already purchased a 24V 15A BMS before I slightly understood all of this. I was also able to obtain more cells since my original idea, so I was planning a 7S10P pack (around 30Ah), 70 cells total. I see each cell can do around 5A, making a 10P pack put out 50A total. If I stick with my 24V 15A BMS, that will give me 15A * 24V watts, or 360 watts total for my 500 watt motor. I’m going to number these to make it easier:

Next comes the heat shrink tube. Large diameter heat shrink tube is hard to find, and I got lucky https://en.wikipedia.org/wiki/Electric_bikes a big score of different sizes from a Chinese vendor before his supply dried up. Your best bet is to check sites like eBay for short lengths of heat shrink in the size you need.

I am having 36v lithium battery with 4.4 Ah(segway -balancing wheel battery pack ) but i want to convert this battery in to 36v with 9 ah is it possible to add one more 36v lithium 4.4 ah battery with this and i can use as 36v 8.8 ah battery ???? please help me iam not getting lithium battery in india for my e bike

Yea lead acid is a great way to cheaply get into ebikes and test new motor/controller combinations. Keep in mind though that your performance will increase when you switch to lithium. It’s easy to do though, as the bike doesn’t care what chemistry it receives, it just sees volts and amps. Good luck!

Most of the problems occur when charging an ebike because they are unsupervised and that is when a LiPo fire can burn down a house etc. Use common sense on where you are going to charge your bike or battery pack, so that if it does burst into flames it does not take your house with you. I have a big steel barbecue grill set up in my entryway which  I charge my battery packs in  as nice safeguard.  This involved taking the battery pack out of the bike after each ride but I am OK with that:

Make sure to consult the wiring diagram for your BMS, because some BMS’s have one more sense wire than cells (for example, 11 sense wires for a 10S pack). On these packs, the first wire will go on the negative terminal of the first parallel group, with all the rest of the wires going on the positive terminal of each successive parallel group. My BMS only has 10 sense wires though, so each will go on the positive terminal of the parallel groups.

My series connections are between each group of 3 parallel cells. So all the connections that go across the short side of the pack are parallel connections, and all the connections that run along the long end of the pack are series. It doesn’t always happen that way, but the shape of this pack forced that geometry.

As you sugested in one of your articles, using lead acid is a great way to prototype the build, so if I am happy with the performance if not the weight of the lead-acid, I can convert to lithium in the future and save some big weight.

For people who are new to the hobby, ready-made lithium packs are the way to go. Several manufacturers offer ready to go Lithium packs with a built in Battery Management System (BMS) at affordable prices.

The next consideration is ensuring that the battery is large enough for your required travel range; it’s no fun having a battery go flat before the end of your trip. In order to determine the range that you will get from a given battery, you need to know both the watt-hour capacity of the battery, and how much energy you use per kilometer. Sounds complicated? Not really. As a rule of thumb most people riding an ebike at average speeds consume about 10 Wh/km from their battery, and this makes the math very easy. If you have a 400 watt-hour battery, you can expect a range of 40km. A 720 watt-hour battery? ~72km

Then I took the sense wire labeled B1 and soldered it to the positive terminal of the first parallel group (which also happens to be the same as the negative terminal of the second parallel group, as they are connected together with nickel strip).

“lithium bike battery +batteries for electric bicycles”

Yes, I’ve seen this problem. Homes that have only a 10A circuit breaker are often not enough for these welders. The room I wanted to use mine in had a 10A, so I switched it for a 20A breaker at the breaker box and now it works fine.

Hello Micah: Thanks for this most interesting and useful article! I want to build a battery in a 39mm x 520mm seatpost for fueling a 250W motor that normally uses a 7.2 Ah – 25 V bottle-shaped battery. The new seatpost battery should only have an autonomy of 7 miles of steep hills (40%) between each daily charge. What are your recommendations? Happy day! Fred

3. Lastly, I assume if the BMS & battery were able to produce the 50A X 24V watts of 1200W that my electric motor would only ever use the 500W it is rated for? As in the E bikes controller would only draw around 500W?

When you buy a Hobby King pack, it will have a number of these large cell LiPo’s strung together like this 6 cell in-series (6S) pack. The big downsides of this pack is that it will only last you in best case maybe 300 charges and it is volatile, and susceptible to possible fire if not well managed and cared for.  When using cobalt-based LiPo, it is best to use some kind of BMS, and also you should charge it in a safe location.

Regarding the soldering of cells: generally it is not recommended as no matter how you do it, a soldering iron will still transfer more heat than a spot welder. That being said, I have seen packs that have been welded using both solid or braided copper wire. I’ve also seen someone use copper wick soldered to the cells terminals. It’s impossible to know exactly how much of an effect that the heat transfer had on the cells but if you don’t mind taking a risk of some level of deterioration of the cells performance, then it technically is possible to solder the cells together.

I’m mostly kidding, but if you use cells that are rated for more current than you’re trying to pull from them, you’ll create a lot less waste heat and both options will be perfectly fine and healthy for the battery.

Used PL-350 electric bike kit, The battery does not charge. Charger is fine but only shows a red light. It sat dead for about a year. Then the controller showed about 80% after charging. Everything wo…

The high C-rate is not the only reason LiPo is adored by the high performance crowd, the addition of Cobalt to the cathode meant that more power would fit in a smaller package. This was driven by the boom in Radio-Controlled (RC) models in the late 1990’s (RC airplanes, cars, helicopters, etc). When that market suddenly expanded, an Australian enthusiast started a company to supply RC parts from factories in China. Hobby King.com was born. Last year, due to popular demand, HK has opened warehouses in The USA and in Germany (edit: even more countries have HK warehouses now).

Linear packing, on the other hand, will result in a narrower pack that ends up a bit longer than offset packing. Some people say offset packing is more efficient because you can fit more cells in a smaller area by taking advantage of the space between cells. However, offset packing creates wasted space on the ends of parallel group rows where gaps form between the edge of the pack and the ‘shorter’ rows. The larger the battery pack, the less wasted space is taken up compared to the overall pack size, but the difference is negligible for most packs. For my battery, I decided to go with offset packing to make the pack shorter and fit easier into a small triangle bag.

Its low C-rate of 1C means you need a large pack if you want higher amps. Justin at ebikes.ca was an early adopter of LiMn for his E-bikes because his customers wanted a trouble-free product that wasn’t fussy and lasted a long time. Makita cordless tools use LiMn, as do many laptop computers. Last year Zero E-motorcycles were using LiMnO2, but this year they moved up to NMC (found listed below). [edit: Due to customer desires and safety concerns, LiMn has been improved and now in 2014, there are high current LiMn]

Wear safety goggles. Seriously. Don’t skip this one. During the process of spot welding it is not at all uncommon for sparks to fly. Skip the safety glasses and head for chemistry lab style goggles if you have them – you’ll want the wrap around protection when the sparks start bouncing. You’ve only got two eyes; protect them. I’d rather lose an arm than an eye. Oh, speaking of arms, I’d recommend long sleeves. Those sparks hurt when they come to rest on your wrists and forearms.

I hope not to have to replace the whole battery pack and wondering if it can be salvaged by replacing the just the dead cells and burnt connectors, or do you think the damage is too extensive to be worth repairing it?

LiMn/LiMnO2-Lithium Manganese Oxide. Adding manganese to the cathode made this chemistry more stable and less sensitive to individual cell balancing issues. If you were using LiFePO4, and one cell began losing its amp-hour capacity, the rest of the pack would get dragged down to the weakest cells level. Demanding high amps with one weak cell in the pack would cause the entire pack to wear out much earlier than it should have.  With LiMn, the packs just seems to stay in balance, with all the individual cells aging equally.

Actually I have ran into a problem – a few days ago I was riding it up a hill on a hot day when the power cut off and it wouldn’t start again. When I tried to charge it, the light on the charger just flickered from green to orange. I took out the battery and found that one of the cells had corroded from what looks like overheating. I think that the battery pack failure was most likely caused by too much of a load applied to the battery pack.

I use white 2mm thick craft foam and cut out a shape slightly larger than my pack. I wrap it up and seal it with electrical tape. It doesn’t have to be pretty, it just has to cover the pack. Your next step will hide the foam from view.

Some of the NMC sellers are advertising their chemistry as 5C, but real-world use by E-bike builders has them calling NMC a solid reliable 3C chemistry, which can provide a continuous 30A from an affordable and compact 10-Ah battery (temporary peak amp-draws can be higher, as it is with any of these chemistries). This may sound only as good as the most recent LiFePO4, but NMC is smaller, and is not as fussy about keeping the individual cells balanced.

Your battery pack size is based on voltage and amp-hours. The higher the voltage and the higher the amp hours of your battery, the more range your battery will give you. A 48V 10-Ah pack gives you 480 watt hour (48 X 10). This gives you an easy way to determine exactly how much battery you are buying. The wattage of a battery is the only accurate determinant to judge what range your finished ebike will have.

For this tutorial, I’ll be using the green Panasonic 18650PF cells shown above. Lately though I’ve been using 18650GA cells like these, which are a little bit more energy dense, meaning more battery in less space.

Alternately, you can separate the batteries and charge each with its own charger, but then you have some small risk of reconnected the batteries when one is charged and the other is flat, if for some reason one of the batteries didn’t get charged up properly. We usually recommend leaving the packs parallel connected at all times.

Next, regarding your question of paralleling the batteries. Yes, you can parallel them, and you can do it even before connecting to the controller. The biggest safety issue (and damage issue) though is to always be sure they are at the exact same voltage when you connect the two batteries in parallel. The easiest way to do this is only to connect them in parallel when you’re sure they are both fully charged.

3. i saw 18650 and 26650 li ion batteries which are more powerful such as 6000 – 8000 mah. i think they are fake??? i need 48v 10ah or 20ah minimum i guess as a pack ??? your advices are important. thanks for all…

This is the old technology for e-bikes that is heavy as bricks and does not have longevity. Lead acid will double the weight of your electric bike. Unless you have to because of money restraints, batteries for e bikes advise to steer way clear of lead acid batteries.  Your bike will have a completely different feel and range if you spend the money on one of the new lithium technologies.

Remember, if a battery with a certain chemistry can “survive” at 2C, it may actually last much longer if it is sized so that the amp-draw from the controller/motor is only 1C. If it can actually be run at 2C, but it dies in a month with daily use…and yet if sized to run at 1C it lasts a year? Legally the manufacturer is not lying by calling it a 2C battery. There is nothing wrong with that, but…we here want E-bike customers to be aware of the real-world results so they can make an informed decision, and avoid the disappointment that could turn off a lot of potential E-bikers to a wonderful sport and hobby.

“replacement battery for electric scooter +electric bike battery”

A recent quote from ES member SamTexas on claimed max C-rates: “…I have in front of me Samsung’s own Nickel (Manganese) 18650 cells….I have tested these cells at 3C continuous and they do deliver full capacity at that rate. Push it to 5C and they become hot and capacity is greatly reduced…“

One question regarding the specific battery BMS you used in this build: It uses a different wire for charging vs discharging the battery. Does this mean that the regenerative braking feature cannot be used for this battery?

All the help and knowledge I’ve provided here on EbikeSchool.com is 100% free, and I try to assist readers as much as possible in the comments section of each article. If you want to support this site and help me keep it free (and ad free), consider checking out my ebook and video course on building ebikes.

I purchased the 220v welder, which obviously was intended to run on non-US half of a phase 220v, Of course we have full single phase 220v, so could you supply me with a hint on how to wire the unit for US 220 v.

Next, plan out your cell configuration on your computer or even with a pencil and paper. This will help ensure you are laying out your pack correctly and show you the final dimensions of the pack. In my top-down drawing below I’ve designated the positive end of the cells in red and the negative end of the cells in white.

That’s exactly correct. You’d start by welding 10 parallel groups of 4 cells each, then you’d connect those 10 parallel groups in series to make one rectangular battery. I’ve done many 10s4p packs just like that for 36V 10ah ebike batteries.

You can certainly use a second 4.4AH battery in parallel to double your range, but you’ll want to make sure the batteries are at the same state of charge when you connect them in parallel, or use a diode in between them, to keep one battery from discharging the other if the charge states are unequal.

I am planning on making a 6S2P LifePO4 pack that has a voltage of 19.2V. I have a 6 cell BMS that does balancing (and that is intended to work with 6 LifePO4 cells). I need some help selecting a charger to charge this pack, however, particularly regarding the charger’s voltage specification.

But having read through the document mostly, not completely, I simply stopped reading further due to incorrect usage of words and many bad spellings, some of which would not be caught by a spell checker – “table” for “stable” for example.

Lastly, regarding the spot welder. I actually prefer to use the kind like you said, with the two arms that lift up and provide equal pressure at each weld. The kind with two long welding cables like this welder has both options which is nice, especially for if you need to reach to the middle of a pack to make a repair or if you missed a weld. I mostly use the short rigid arms though and just weld one row at a time before adding more cells – that way I can reach all the cells with the short arms.

“The secret of NMC lies in combining nickel and manganese. An analogy of this is table salt, in which the main ingredients of sodium and chloride are toxic on their own but mixing them serves as seasoning salt and food preserver. Nickel is known for its high specific energy but low stability; manganese has the benefit of forming a spinel structure to achieve very low internal resistance batteries for motor scooters offers a low specific energy.

Nickel Metal Hydride batteries are about 20% lighter and 30% less voluminous than a NiCd pack of the same capacity. They have similar discharge and charge characteristics, but because of the higher energy density they are available in higher capacities than NiCd packs. Because NiMH is safe for disposal in the landfill while Nickle Cadmium is not, the metal hydride has almost completely replaced cadmium in most consumer batteries.

I would advise against connecting one battery to the other’s charging port. That charging port, as you correctly stated, is wired to a charging circuit on the BMS which is usually meant to take 5A max, sometimes less, whereas the discharging side of the BMS usually puts out at least 15A, sometimes much more. You can easily fry your BMS by connecting a second battery to its charge port.

Your battery pack size is based on voltage and amp-hours. The higher the voltage and the higher the amp hours of your battery, the more range your battery will give you. A 48V 10-Ah pack gives you 480 watt hour (48 X 10). This gives you an easy way to determine exactly how much battery you are buying. The wattage of a battery is the only accurate determinant to judge what range your finished ebike will have.

When it comes to the nickel strip you’ll be using to connect the 18650 batteries together, you will have two options: nickel-plated steel strips and pure nickel strips. Go for the pure nickel. It costs a little bit more than nickel plated steel but it has much lower resistance. That will translate into less wasted heat, more range from your battery, and a longer useful battery lifetime due to less heat damage to the cells.

“scooters batteries battery electric bicycle”

Continue down the row of cells placing a weld on each cell. Then go back and do another set of welds on each cell. I like to do 2-3 welds (4-6 weld points) per cell. Any less and the weld isn’t as secure; any more and you’re just unnecessarily heating the cell. More and more welds won’t increase the current carrying ability of the nickel strip very much. The actual weld point isn’t the only place where current flows from the cell to the strip. A flat piece of nickel will be touching the whole surface of the cell cap, not just at the points of the weld. So 6 weld points is plenty to ensure good contact and connection.

I use my welders on 220V, though 110V versions are available. If you have access to 220V in your home (many 110V countries have 220V lines for clothes dryers and other high power appliances) then I’d recommend sticking with 220V. In my experience the 110V models seem to have more problems than their 220V brothers. Your mileage may vary.

If you are using 2.5AH cells then yes, it will be 5AH with a 2p configuration. If you use cells with higher capacity, like Sanyo GA http://electricbikebatterys.com that are 3.5AH, then you’ll have a 7AH pack with only 2p. Make sure your cells can handle the current that your electric scooter (and namely the controller) will try to draw from it.

This is what I refer to “small cells”, the 18650 (cordless tool) type cells which need to be spot-welded or soldered together to form a large pack. The big advantage of these cells is they offer better cooling because of the nature of their shape to the LiPo soft pouches, and therefore have the capacity to last longer.

One of the easiest ways to increase the current handling capability and range is to put two or more batteries in parallel. In general, with lithium batteries of the same nominal voltage, this is no problem. It is perfectly fine to mix old and new lithium batteries in parallel, or even batteries from different manufacturers and with different capacities, so long as they are the same voltage. We stock a parallel battery joining cable to facilitate connecting packs this way. 

Where things can get a bit dicey is in charging batteries that are parallel connected. If you leave the batteries in parallel while charging, then the charger current will get shared between the batteries and you can be sure that they are always at the same charge level. However, that does mean one of the batteries will be getting charged through the discharge port, and depending on the specific BMS circuit it may not have overcharge protection on the discharge wires.

When you wire in series you only increase voltage, not amp hours. So you’d have a 48V 5AH pack in that setup. Not enough range, in my opinion. If you want my advice, the single best upgrade you can do to that bike is to replace the battery and controller for 48V units. It will give you about 30% more speed and power. You won’t need to drill vent holes or anything, that motor can handle 48V as long as you aren’t riding up any 5 mile long uphills with a 250 lb rider. Shorter uphills and flat land will be fine all day long.

A recent quote from ES member SamTexas on claimed max C-rates: “…I have in front of me Samsung’s own Nickel (Manganese) 18650 cells….I have tested these cells at 3C continuous and they do deliver full capacity at that rate. Push it to 5C and they become hot and capacity is greatly reduced…“

Next, plan out your cell configuration on your computer or even with a pencil and paper. This will help ensure you are laying out your pack correctly and show you the final dimensions of the pack. In my top-down drawing below I’ve designated the positive end of the cells in red and the negative end of the cells in white.

I want to build a 36v ebike battery for my 36v 500w motor. What battery you recommend for me which gives the enough current and capacity. My plane is to build a battery with 40 cells 10 in s and 4 in p,

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100~240VAC Universal AC input Full range LiFePO4/Lithium Ion/Lead Acid 4000W Battery Charger Two S2500 model in parallel. Power:4000Watts; Protection function: / Overload / Over voltage / Over temperature / Over current / Reverse polarity / Power off or trickle after finished charging; 2 years warranty

There are six rechargeable battery types that have seen regular use in electric bicycle battery packs. We have never been involved with lead acid batteries, and discontinued dealing NiCad and NiMH packs in 2010.

Introduce Yukon Trail 2018 new model Xpedition Features: 350w motor Battery: Samsung lithium battery (light weight 5 lbs with case) Speed/Mileage: up to 20MPH, up to 28 miles per full charge (varies b…

I’d recommend going with a cell that can output 10A, giving you 40A continuous power rating. You’ll use less than that, meaning the cells will be happier (and cooler). Something like the Sanyo 18650GA or LG MJ1 would give you good power and capacity (both are around 3,400 mAH per cell).

Rated Capacity: 10Ah. Recommended to be used with 36V 250W electric bicycle motor. 36V 750W 20″ Front Tire e-Bike. Charge Current: 2A. Model: Bottle Type. 1 Year manufacturer warranty for CHARGER. Use…

When choosing a battery for your bike, not only is the weight important but the volume is also important. You want your pack as small as possible so its easy to stow and easy to hide. So therefore you should consider you battery’s volume, not just its weight. For sure you need to go with a lithium chemistry and not an old school heavy and large Sealed Lead Acid (SLA) or Nickel-Metal Hydride (NiMH) chemistry.

And if you don’t want to purchase my book (or you already have a lot of ebike knowledge), you can still support this site by simply clicking on this link before you shop on Aliexpress. Basically, that’s an affiliate link that shows Aliexpress that you came to them via my site. It doesn’t effect you at all, but if you make a purchase, this site will get a small percentage of the profit that Aliexpress makes. It’s a simple way to help support this site so I can pay the hosting and keep providing more free info (and to keep this site free of annoying ads). I have some of those affiliate links on a limited number of articles on my site. When I personally buy and test products that I find to be a combination of great quality and great prices, like these batteries, for example, I like to share them through those affiliate links. Again, it costs you nothing, but it allows me to keep cranking out more info and content for you guys!

I’m sorry but I’m not certain. Here in Israel we are on 50hz so I haven’t tried that model on 60hz. I do however have some friends in the US that have that model on 60hz. They have been happy with it, but I haven’t used it myself so I can’t say how it compares to my experience.

A better and simpler solution would be, as you said, to carry a second battery and just swap the connector from the old battery to the new one when the old battery is depleted. There are a few types of bottle batteries out there, I recommend googling “bottle battery” if you haven’t yet, you’ll likely find a few options. I don’t know if this is the same model as yours, but some common styles similar to your description can be found here and here.

The 48V, 8AH lithium battery of this ebike is removable. Material: Aluminium alloy frame. E-bike & Assisted bicycle, you can choose the E-bike to enjoy a long time travel, and also exercise. Combining…

I have found this BMS which is cheap (necessary for my project) and it is shipped from the UK. Because it is so cheap do you think that it may not be balancing? http://www.ebay.co.uk/itm/400984825723?euid=0502c7e2b2c744ec8857879d65d46e08&cp=1

To determine how much power you need, you’ll need to determine the voltage you want and the capacity you need to supply that power (voltage times current). Read this article to learn more about calculating your ebike’s power: http://www.ebikeschool.com/myth-ebike-wattage/

LiFePO4-Lithium Iron Phosphate. This was the first lithium chemistry that really took off for use in cordless drills and laptop computers. Mass production brought the prices down, and E-bikers began buying cordless drill packs and gutting them for the cylindrical cells, so they could be re-configured from the stock 18V up to 48V (or more). The common low C-rate was around 1C, so builders began making packs for high voltage to get better performance without stressing the pack by trying to pull high amps. LiFePO4 requires a sophisticated Battery-Management-System (BMS) to stay healthy.

If none of our own battery offerings meet your needs, we can also highly recommend the knowledgeable folks at Batteryspace.com and EM3EV as alternate suppliers of lithium battery packs in a wide range of capacities, form factors, and voltages. 

I am however encountering problems in finding a BMS for my pack which will be 2 or 3 P and 7 S to replace 24V 6 AH in frame battery pack. Can you please enlighten me as to where I can access a suitable BMS. Thanks for any help. K.

I am planning to build a 14s7p pack with the GA batteries for a little over 1 KW of power. I went to the BesTechPower site and their are several 14s BMS’s there. Which one would you recommend for a battery this size? Can you send/post a link to the specific on on their site? thank you.

This had led me to believe that if there is too much load being exerted on the bike (i.e. the current being drawn from the battery is too high) then either the BMS or the controller trips and cuts out. However I am reluctant to believe that the BMS is causing the trouble as it has a 40A rating on it (this link shows the exact BMS) http://www.aliexpress.com/item/Electric-motor-car-13S-48V-40A-BMS-lithium-ion-battery-BMS-Used-for-48V-20Ah-30Ah/32484213150.html?spm=2114.13010608.0.62.evx6sX .

Combining the metals brings out the best in each. NMC is the battery of choice for power tools and powertrains for vehicles. The cathode combination of one-third nickel, one-third manganese and one-third cobalt offers a unique blend that also lowers raw material cost due to reduced cobalt content“

“diy electric bicycle -emoto electric bike battery”

The only thing left to do at this point is to add the connectors, unless you did that before you soldered the wires on, which I actually recommend doing. But of course I didn’t do that, so I added them at this step, being careful not to short them by connecting only one wire at a time.

Thank you for the article! I am currently making a battery for an electronic skateboard, so I need the layout to be as thin as possible to allow ample room underneath the deck. Currently, I have 6 packs of 3 cells welded in parallel, and would eventually like to create a battery which is 9 cells long, 1 wide, and 2 high, for 18 in total (the two packs of nine would then be welded in series). I am wondering if I could be able to make 2 battery packs by welding 3 of my current 3 cell packs together in parallel to make a long, yet skinny pack, and then welding both packs of nine in series using the alternating system. Essentially, I would be creating a pack that would look like 3 of the ones you show above when making your first series connection. Let me know what you think, and thank you!

36V 10ah Lithium battery (Included with the battery is the charger and mounting Bracket). Standard 26 in Front Wheel 500w brushless motor hub (works with V-brake or disc brakes). Pedal Assistance syst…

I have come to the conclusion that a 48v battery would probabky be sufficent for my needs. I need to ride continuously for at least 7-8 hours–but prefer up to 10 hours– at 15-20mph everyday. Although I also need a top speed of 30mph, at times. If my math is right, in order to accomplish this I need to build at least a 14s8p battery. After running these specs through a simulator I found that the power starts to drop at about 1150 watts and 20mph.

I am currently building my own 36v battery and now using some of the ideas you have put here. but I am wondering what is going to be the best charger for charging the battery?? As I am doing on the cheap, I am utilising a 12v 6A charger which I previously had. My plan was to couple with a 12v to 36v step up DC transformer but then realised that this may not be enough to charge the battery fully. This is because the full charge voltage on the battery is actually 41v which would be higher than the step up transformer. The next option is a 48v charger which would be too high.. Or would the BMS kick in and protect from over voltage?? This is all theory at the moment so I am probably missing something.. Could you suggest a charger method. Am I on the right track?

2018 model Pedalease Estar MTB electric mountain bike 1000w or 1500w rear hub motor with option of 48v 10ah, 48v 11.6ah and 48v 17ah lithium battery. Motor: Pedalease 1000W or 1500w rear drive brushle…

You will find here all Li-Ion/LiFePO4 EBike battery packs and cells, battery management system(BMS). This category includes 12V~72V Li-Ion/LiFePO4 EBike battery packs and cells, EBike bottle battery, high power battery and high C-Rate cells, 4~24 cells in series Li-Ion/LiFePO4 bleeding balancing BMS and 5~13s smart BMS.

You’ll see two dots where http://electricbikecharger.com weld was performed. Test the weld by pulling on the nickel strip (if it’s your first time using the welder). If it doesn’t come off with hand pressure, or requires a lot of strength, then it’s a good weld. If you can easily peel it off, turn the current up. If the surface looks burnt or is overly hot to the touch, turn the current down. It helps to have a spare cell or two for dialing in the power of your machine.

The Panasonic NCR18650B cells you have are very good quality cells. I used similar cells also made by Panasonic, but mine are the NCR18650PF (not B). The difference is that yours have more capacity (mine are 2900mAh, yours 3400mAh) but yours have a lower constant current draw rating. I don’t remember what it is off the top of my head, but I don’t think it’s much more than 5A per cell. So just make sure that you either use enough cells in parallel and/or limit your controller to not draw more power than the cells can handle. Check the cell specification sheet which you can find on Google somewhere to ensure that you are staying within the cells’ limit.

Battery packs are made up of individual cells connected together. Each cell has a more or less constant voltage dependent on its chemistry. For NiCad/NiMH, this is about 1.2V, for lead acid it is 2.0V, and for lithium cells it is on the order of 3.7V. Typical ebikes and scooters are designed to run on 24, 36, or 48 Volts, so a number of cells have to be series connected into a ‘battery’ that has the desired net voltage. A nominal 36V pack could be made from 10 lithium cells, 18 lead acid cells, or 30 NiMH cells.

When comparing between battery chemistries, one of the most relevant metrics is the Energy Density in watt-hrs / kg. This figure says how heavy a battery pack will have to be to achieve a certain range. For Lead Acid it is 20-30 whrs/kg, for NiCad it is 35-40 whrs/kg, NiMH is 50-60 whrs/kg, Li-ion is ~110 whrs/kg, and Li-Polymer is up to 160 whrs / kg. Knowing these values makes it easy to project the weight of a pack without having to look up data from the manufacturer.

The BMS I chose is a 30A maximum constant discharge BMS, which is more than I’ll need. It’s good to be conservative and over-spec your BMS if possible, so you aren’t running it near its limit. My BMS also has a balance feature that keeps all of my cells balanced on every charge. Not all BMS’s do this, though most do. Be wary of extremely cheap BMS’s because that’s when you’re likely to encounter a non-balancing BMS.

A big downside of lithium batteries is that they are much more expensive than lead acid batteries. Prices vary depending on the voltage and capacity of the lithium battery, but standard ebikes usually have lithium batteries starting in the $300 range and rising quickly from there. Most bikes I build have lithium batteries in the $400-$500 range.

There are many different types of lithium ebike batteries to choose from. I’ll give a short summary of the different types of electric bicycle specific lithium batteries here, but you can get a more detailed description as well as the pros and cons of each type of lithium battery in my article Not All Lithium Batteries Were Created Equal.

“electric bike batteries lithium _bike batteries”

It is possible to do it that way, however there are some compelling reasons not to. 1) By first joining all the series cells you would end up with multiple high voltage groups, which means both the chance and consequences of an accident are greater. When you’re working with lots of exposed batteries with nickel conductors and metal tools flying around, the last thing you want is more high voltage possibilities for shorts. 2) Doing series cells first would be come unwieldy, physically. A series group is only connected at either the top or bottom of alternating cells. Without having multiple cells side by side to add stability, a long chain of single cells will need either a pile of glue or some type of physical holder to support the chain. and 3) most battery spot welders can only reach about 2 cells deep into a pack, meaning you’d have to either add very short nickel strips to each series group connecting only two groups (which means twice the welding and twice the cell damaging heat) or have long uncontrolled nickel strips hanging off the sides, again risking shorting.

To determine how much power you need, you’ll need to determine the voltage you want and the capacity you need to supply that power (voltage times current). Read this article to learn more about calculating your ebike’s power: http://www.ebikeschool.com/myth-ebike-wattage/

The best method is to use a trusted vendor. They interact with the cell providers and are the best way to confirm whether cells are fake or not. It can be incredibly difficult to tell whether a cell is fake or not just by picking it up from the table. There are some giveaways like different printing on the wrapper, slightly different color, different stamp, different weight or different shell design, but all of those can be mimicked. That’s why I use only a handful of vendors that I’ve worked with continuously and who I know have always given me good quality cells. I had to go through some low quality ones until I found the sources I buy from now.

I then took my second sense wire (or your third sense wire if you have one more sense wires than parallel groups) and soldered it to the positive terminal of the second parallel group. Again, note that I’m soldering this wire to the nickel in between cells to avoid heating any cell directly.

Also changing the fuse to a higher one could cause the wires to start a fire and the whole house would burn down if the wires are not thick enough. Also in sweden a fuse gets bigger as they are rated higher so you can fit a 20A fuse in a 10A slot, for safety.

There are two main levels of spot welders currently available: hobby level and professional. A good hobby model should run about $200, while a good professional one can easily be ten times that price. I’ve never had a professional welder because I just can’t justify the cost, but I do own three different hobby models and have played around with many more. Their quality is very hit or miss, even on identical models from the same seller. Unfortunately the lemon ratio is quite high, meaning you could fork over a couple hundred bucks for a machine that just won’t work right (like my first welder!). Again, this is a good reason to use a site with buyer protection like Aliexpress.com.

There are formulas out there for calculating the exact size of heat shrink you need but I often find them overly complicated. Here’s how I figure out what size I need: take the height and width of the pack and add them together, and remember that number. The size of heat shrink you need when measured by the flat width (half the circumference) is between that number you found and twice that number (or ideally between slightly more than that number to slightly less than twice that number).

Battery manufacturers are continuing to research for developments in dozens of battery chemistries, and a couple of years ago, a big improvement to LiPo/LiCo chemistries began to be produced. A high-Cobalt cathode (LiCo) provides very good power density, but how can we make it more stable and reliable? Here’s a quote from batteryuniversity.com

You can use any connectors you like. I’m a big fan of Anderson PowerPole connectors for the discharge leads. I used this other connector that I had in my parts bin for the discharge wires. I’m not sure what that type of connector is called, but if someone wants to let me know in the comments section then that’d be great!

Lithium batteries are also small enough to allow you to place your batteries pretty much anywhere on your bike. This is especially true for people who want to assemble their own pack or use heat shrink wrapped lithium batteries instead of hard case lithium batteries with prefabricated bicycle frame mounts. This can help spread the weight around or hide the batteries to make a stealthier bike.

I hope not to have to replace the whole battery pack and wondering if it can be salvaged by replacing the just the dead cells and burnt connectors, or do you think the damage is too extensive to be worth repairing it?

Good question. The answer comes down to the difference between “nominal voltage” and “actual voltage”. LiFePO4 cells are nominally called 3.2V cells, because this is their voltage in the middle of their discharge curve, at about 50% discharge. They actually charger to a higher voltage though, about 3.7V per cell. That means that you need a charger that has an output voltage of 3.7V x 6 cells = 22.2V DC. This is going to be a bit harder to find because most LiFePO4 packs come in multiples of 4 cells, (4, 8, 12, 16 cells, etc) so finding a charger for a 6S pack might take some searching. This charger is a good quality one meant for 8 cells (output voltage of 29.2V DC) but if you put a note in the purchase order, the seller can adjust the output for 6 LiFePO4 cells (22.2V DC). http://www.aliexpress.com/store/product/aluminum-shell-24V-29-2V-3Amper-Lifepo4-battery-charger-high-quality-charger-for-8S-lifepo4-battery/1680408_32274890691.html

Small hard-cased A123 cells (about the size of a “C” battery) have been salvaged out of power drill packs, car battery packs etc, and have made it into the hands of e-bike DIYers who solder them together in series and in parallel to construct a pack big enough and powerful enough to power an e-bike.

Landcrossers Hailong E-Bike Battery. Case Material:ABS Aluminium alloy. Fuse Installation position:Inside on the PCB. Fuse Diameter(mm):5. Fuse Length(mm):30. Fuse Current: 30A. 1 x Lithium Battery wi…

Whether you’re shopping for a turn-key commercially available electric bike, or trying to find or build a good battery for an e-bike conversion, being able to find the right battery for an electric bike is a difficult task.  The right battery pack is the most difficult part of the e-bike equation. Keep in mind that even if you’re buying a turn-key electric bike, the lithium battery is more than likely the most expensive component in it, and…not all lithium batteries are created equal, so you should know what you are getting before you buy the ebike.

I am new to the ofrum and to the ebike world so I would like to seek some advice please. I have recently bought a sondors fat bike to the UK and want to make some tweaks, I would like to upgrade the battery on a budget, I was thinking of 4 x 12v 5ah lead acid batteries in series, would this give me 48v 20ah or have I got this totally wrong? I want to replace the stock contoller for a 48v 25amp one, would this suffice? lastly it comes with a stock 350w bafang motor, if I make the battery and controller upgrades will the motor handle the increase in wattage? could I drill venting holes in the case cover to expell some heat? Your thoughts and advice would be most welcome,

If you don’t find that, there’s still a chance that it’s the problem, and that the cells simply rose up to a higher voltage and matched the others again once the load disappeared. But it also may be that the load is too high for the BMS. Do you have a cycle analyst? You could slowly increase the throttle and watch how much current you are drawing until the point of cutoff. If it’s well below 40A then you’ll know it’s not a high current cutoff.

LiFePO4/Lithium Ion/Lead Acid 120W Battery EBike Charger. 12V6A,24V3A,36V2.5A,48V2A;  Li-Ion Battery Charge Voltage = 4.2V x the number of cells in series; LiFePO4 Battery Charge Voltage = 3.55V x the number of cells in series.

Nickel Metal Hydride batteries are about 20% lighter and 30% less voluminous than a NiCd pack of the same capacity. They have similar discharge and charge characteristics, but because of the higher energy density they are available in higher capacities than NiCd packs. Because NiMH is safe for disposal in the landfill while Nickle Cadmium is not, the metal hydride has almost completely replaced cadmium in most consumer batteries.

If you are using 2.5AH cells then yes, it will be 5AH with a 2p configuration. If you use cells with higher capacity, like Sanyo GA cells that are 3.5AH, then you’ll have a 7AH pack with only 2p. Make sure your cells can handle the current that your electric scooter (and namely the controller) will try to draw from it.

I am however encountering problems in finding a BMS for my pack which will be 2 or 3 P and 7 S to replace 24V 6 AH in frame battery pack. Can you please enlighten me as to where I can access a suitable BMS. Thanks for any help. K.

I have now come to the conclusion however that i want a pack that is 48V and capable of running a 1000w motor for atleast an hour. I live in a hilly area, i use a downhill bike (heavy) and im not the smallest guy. Im feeling a bit insecure about putting too many cells in parallel. Through the years i’ve read that the consesus is that more than 4 cells in parallel is a risk. Since a 13S4P pack is about 12Ah (with good batteries) i was wondering if you had any input on how i should move on?

I did not intend for the timeline to reflect anything other than what I recall seeing as E-bike battery packs. Some chemistries have been around a long time before they were used by a significant number of E-bikers.

Nissan, Imara, Microvast, and Zero E-motorcycles are now using NMC after extensive testing. Let’s take a quick run down memory lane to show how battery chemistry has evolved in just a few short decades. The following is not the order of their invention, just what my foggy memory recalls as seeing them used in E-bike battery packs.

Manufacturers usually rate their cells’ capacity at very low discharge rates, sometimes just 0.1c, where the cells perform at their maximum. So don’t be surprised if you’re only getting 95% or so of the advertised capacity of your cells during real world discharges. That’s to be expected. Also, your capacity is likely to go up a bit after the first few charge and discharge cycles as the cells get broken in and balance to one another.

For a heavy trailer, I’d add a second brushed motor to the cart, whether the bike has a motor or not. You’d only need 24V, and here’s a discussion about powered trailers. The most important thing for going over sand is to have the fattest tires http://electricbikeframes.com can fit onto the trailer.

If you don’t have an actual heat gun, you can use a strong hair dryer. Not all hair dryers will work, but my wife’s 2000 watt model is great. I own a real heat gun but actually prefer to use her hair dryer because it has finer controls and a wider output.  Just don’t go mess up your wife’s hair dryer!

I’m not familiar with this copper serial connection you’re talking about. I guess you mean to reinforce the series connections to handle more current? As long as you are using enough strips of nickel (and ensuring that it’s pure nickel and not nickel coated steel) then you shouldn’t need copper reinforcements. I try to use at least 1 strip of nickel for every 5A my battery will carry. So if I’m looking for a 20A max load, I’d use 4 strips of nickel in each series connection. That’s easy to do if each cell in a parallel group of 4 cells is connected to the next group by one strip each.

A High-performance Motor acheives a top speed of 20-30km/h with a range of 20km means your ebike commute just got easier. 36V 8AH Lithium-Ion Battery. Motor: 36V 250W brushless. Rang: 18-25km(36v 6ah)…

3. Lastly, I assume if the BMS & battery were able to produce the 50A X 24V watts of 1200W that my electric motor would only ever use the 500W it is rated for? As in the E bikes controller would only draw around 500W?