“lithium bike battery +battery for electric scooter”

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

Capacity: 30Ah. output: 71.4V 5A. Lifecycle of single cell: >85% capacity after 700 cycles, > 70% capacity after 800 cycles. (<1C discharge rate and <1C charge rate). Lifecycle: > 85% capacity after 5…

This makes sense. Yes, it would be possible. You could wire balance connectors and extra discharge plugs to make three packs out of your one 13s pack, such as two 6s packs and a 1s, or two 5s packs and a 3s, etc. Then you’d charge each one, one at at time, using your imax B6 charger. It would take a while, but that’s how you’d do it. Just be careful to not get your connectors confused, as you’ll have three sets of balance wires and three sets of discharge wires.

Panasonic and Samsung are the only manufacturers I know of that are producing this chemistry (several other manufacturers buy these and re-label them as their own). Since you would have to buy the bare cells in order to solder together your own pack, I wouldn’t have mentioned these just yet, but…EBAY-seller supowerbattery111 is selling these, and…he will also professionally spot-weld the cells into groups for a small fee, which reduces your pack-building efforts down to about 1/10th of what it would be otherwise. His main business seems to be refurbishing cordless tool battery packs that have worn out.

Regarding the soldering of cells: generally it is not recommended as no matter how you do it, a soldering iron will batteries for motor scooters 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 then put one set of welds on each cell end of the first parallel group, effectively tacking the three nickel strips in place. Then I added another set of welds on each of the negative terminals of the second parallel group. This gave me 6 weld sets, or one weld set for each cell. Lastly, I followed up those single weld sets with another couple welds per cell to ensure good contact and connection.

Lead acid batteries are much larger and heavier than lithium batteries, limiting their placement on ebikes. They almost never come packaged with ebike specific mounting hardware which means that they generally have to go in a bag on the rear rack or in panniers on either side if the rear wheel. Mounting them up high on the rack isn’t a good idea either because it will negatively affect handling. Generally speaking, you want to mount your batteries as low as possible to keep the center of gravity of the ebike lower towards the ground. This will significantly improve your ebike’s handling.

One of the main disadvantages of lead acid batteries is their weight. There’s no beating around the bush here, SLAs are HEAVY, as you might guess by the inclusion of “lead” in the name. You’ll need a strong mounting solution on your ebike to handle the extra weight of SLAs. You should also be aware that lugging that extra weight around is going to negatively impact your range. The best way to improve the range of any electric vehicle is to reduce weight, and SLAs are kind of going the opposite way in that regard.

Wow, that’s a really interesting way to do it. So their auxiliary battery connects to the charge port of the primary battery, which means it’s not actually powering the bike but rather just charging the primary battery, which then powers the bike. Not the most efficient way to do it, but it’s simple and elegant.

I am just trying to install a battery on a velomini 1 that I traded for. I don’t have a problem using the above battery as a hang on battery, but don’t know if it has the BMS in it or if my current charger would charge it. It is pretty cheap.

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.

One more thing to note about large diameter heat shrink: unless otherwise stated, this stuff usually shrinks about 10% in the long direction, so you’ll want to add a bit extra to the length to account for both overlap and longitudinal shrinkage.

“e-bike battery +battery pack for electric bike”

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Great article! Have ordered everything BUT i have a big problem with the spotwelder. Most homes in europe are limited to 10A and this spotwelder alone drags 15A just to powerupp!!!! I can even start it without blowing both fuses! And when welding it wants 50A-800A which you need a an actual POWERPLANT for!

I placed the first parallel group positive side up, and the second 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.

http://www.aliexpress.com/item/SUNKKO-709A-1500W-welding-machine-small-battery-spot-Welder-with-welding-pen-for-18650-pack-welding/32384498157.html?spm=2114.01020208.3.132.T8tjqL&ws_ab_test=searchweb201556_0,searchweb201602_1_10037_10033_507_10032_10020_10017_10021_10022_10009_10008_10018_101_10019,searchweb201603_1&btsid=06a7c525-fb11-425d-8614-730ff4b43d7e

I should really change that $2 cutoff to more like $2.50, which is more reasonable for quality cells. Basically, the cheapest ‘good’ cells are Samsung 26F cells, which can be had for usually around $2.50 – $2.90 if you are buying in any large quantity, like at least 100. Expect to pay more like $3.00 or so if you’re buying only 40 cells. 26F cells are also limited to 5A discharge though, so you’ve got the same issue as with the NCR18650B cells from Panasonic.

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.

18650 cells, which are used in many different consumer electronics from laptops to power tools, are one of the most common battery cells employed in electric bicycle battery packs. For many years there were only mediocre 18650 cells available, but the demand by power tool makers and even some electric vehicle manufacturers for strong, high quality cells has led to the development of a number of great 18650 options in the last few years.

You’ll also want to test out the battery with a fairly light load in the beginning. Try to go for an easy ride on the first few charges, or even better, use a discharger if you have one. I built a custom discharger out of halogen light bulbs. It allows me to fully discharge my batteries at different power levels and measure the output. This specific battery gave 8.54 Ah on its first discharge cycle at a discharge rate of 0.5c, or about 4.4 A. That result is actually pretty good, and equates to an individual average cell capacity of about 2.85 Ah, or 98% of the rated capacity.

A cell that provides close to a “real world” 2.8-Ah per 18650 cell is pretty impressive, and the 3C current-producing capability is perfect for E-bikes (a 15-Ah pack can provide a continuous 45A, and our favorite power level of 30A can be provided by a very small 10-Ah pack). If you know of anyone who builds a pack out of these, please contact us, as we are very keen to discover whatever strengths or weaknesses they may have. If you are shopping to buy these, make certain you get these specific part numbers, batteries for electric scooters replacement part numbers will only have half the C-rate.

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.

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.

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.

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.

I am working on a similar project, and was wondering if the BMS’s that you recommended would handle any back EMF from the motor (from regenerative braking, for example.) I see that there are separate leads for charging and discharging, so I’m guessing if current flowed back through the discharge circuit that would be bad. Do you have any recommendations on a BMS (or something different) that would handle this condition?

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.

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.

As far as dimensions, I prefer to use 0.1 or 0.15 mm thick nickel, and usually use a 7 or 8 mm wide strip. A stronger welder can do thicker strip, but will cost a lot more. If your welder can do 0.15 mm nickel strip then go for it; thicker is always better. If you have thinner strips then that’s fine too, just lay down a couple layers on top of each other when necessary to create connections that can carry more current.

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.

While there are a lot of chemical combinations that can and have been made into useful batteries, in practice there are only four rechargeable types readily available in sizes suitable for ebikes. These are Lead Acid (PbA), Nickel Metal Hydride (NiMH), Nickel Cadmium (NiCad), and Lithium-ion or Lithium Polymer.

“make electric bike -lithium bike battery”

The biggest advantage of lead acid batteries is their price: dirt cheap. Lead acid batteries can be purchased from many different online retailers and local stores. Purchasing SLAs locally helps save on shipping and makes them even cheaper. Many hardware and electronic stores carry them. Even Radioshack has them, though you’ll pay more there.

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.

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.

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.

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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

This makes sense. Yes, it would be possible. You could wire balance connectors and extra discharge plugs to make three packs out of your one 13s pack, such as two 6s packs and a 1s, or two 5s packs and a 3s, etc. Then you’d charge each one, one at at time, using your imax B6 charger. It would take a while, but that’s how you’d do it. Just be careful to not get your connectors confused, as you’ll have three sets of balance wires and three sets of discharge wires.

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But there’s still another issue: now if I just slip my pack inside some shrink wrap tube, I’ll still have exposed ends. This is more or less ok structurally, though it won’t be very water resistant and it will look a bit less professional.

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).

I assume you mean 52V (14s, or 14 cells in series) which is a somewhat common lithium ion battery configuration. It works with most 48V setups but provides a little more power than a standard 48V (13s or 13 cell) battery. A good charger I recommend for 52V 14s batteries is this one.

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 batteries for electric scooters replacement if you had any input on how i should move on?

A BMS isn’t necessarily strictly required – it is possible to use the pack as is, without a BMS. But that requires very careful monitoring of the cells of the battery to avoid damaging them or creating a dangerous scenario during charging or discharging. It also requires buying a more complicated and expensive charger that can balance all of the cells individually. It’s much better to go with a BMS unless you have specific reasons to want to monitor your cells by yourself.

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.

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?

3. There’s something that I think you might be missing here. The factor that actually limits current draw is the controller, not the motor or the BMS. Those are “rated” for 500w and 15A, respectively, meaning they won’t overheat at those values. But both can physically pass those values if you force them to. It’s the controller that is actually “pulling” the current. So you should check your controller to see what its current limit is. If it is a 15A limit controller, then it won’t physically pull more than 15A. The fact that your battery can technically put out 1200W just means that it has “oomph” than you’re using, and you’re giving it an easy, healthy life. But if you switched to a 50A controller, suddenly you’d be pulling the maximum current that your battery can supply (and probably overheating your motor if you pull that 50A for a long time).

As much as I want to build a pack just for fun and like buying tools like a spot welder I’m afraid of getting crappy cells at a high price. Whatj’s a good cell to charge at 1C for quick turn around and stay at a low price per cell? 36V 12A would be ok, more is a bonus.

The BMS is for 7S, I connect B1+, B2+, B3+, to the negative of the first serie. B4+ is connected to the positive of the first serie, B5+ positive of 2nd serie, B6+ positive of 3rd serie, B7+ positive of 4rd serie.

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.

One term you will frequently come across is the ‘C’ rate of a battery pack. This is a way of normalizing the performance characteristics so that batteries of different capacity are compared on equal terms. Suppose you have an 8 amp-hour pack. Then 1C would be is 8 amps, 2C would be 16 amps, 0.25C would be 2 amps etc. A higher ‘C’ rate of discharge is more demanding on the cells, and often requires specialty high rate batteries.

If you want to step up a notch on the quality ladder, here is another good charger that I prefer even more, though it’s a bit more expensive: http://www.aliexpress.com/store/product/aluminum-shell-36V-42V-2Amper-Li-ion-Lipo-battery-charger-high-quality-charger-for-10S-li/1680408_32275847257.html

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, we 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.

“enduring cb 10-12 +48 volt scooter battery”

That’s a tough one to answer. It depends on the power of the battery (typically 24, 36 or 48V), the power of the bike (limited in the UK to 250W), the bike’s battery management system, and the way you ride. Some bikes allow you to choose different levels of assist to prioritise speed or battery life, which makes predictions of battery life even more difficult.

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.

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.

I am just trying to install a battery on a velomini 1 that I traded for. I don’t have a problem using the above battery as a hang on battery, but don’t know if it has the BMS in it or if my current charger would charge it. It is pretty cheap.

This page is embarrassingly old, referencing chemistries that are completely obsolete, and is due for a rewrite. In the meantime, we recommend checking out our Battery Kits Product Info page for a more current explanation on lithium specific battery packs.

If the 4P10S multi-tube arrangement was for occasional use on long journeys, then it would be reasonable to release all of the cells and to charge them individually or in parallel to about 4V using a normal little single cell charger. Each would then be “top balanced” yes? Then mount them in the tubes, compress and connect the top terminal array and good to go. I’ve still got the quandary about whether to connect them in parallel to the main battery large output terminal.

It makes very little difference whether you have a small geared motor, a large direct drive motor, or a mid-drive motor. The mileage and range figures for a given battery have to do with how you use the ebike, not which motor system is on the bike.

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.

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.

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.

Next comes the heat shrink tube. Large diameter heat shrink tube is hard to find, and I got lucky with 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.

To wire the BMS, we first need to determine which of the sense wires (the many thin wires) is the first one (destined for the first parallel group). Look for the wires to be numbered on one side the board. Mine is on the backside of the board and I forgot to take a picture of it before installing it, but trust me that I took note of which end the sense wires start on. You don’t want to make a mistake and connect the sense wires starting in the wrong direction.

Many people are tempted to use cheaper 18650’s sold under names like Ultrafire, Surefire and Trustfire. Don’t be one of those people. These cells are often marketed as up to 5,000 mAh but struggle to get more than 2,000 mAh. In actuality, these cells are just factory rejects, purchased by companies like Ultrafire and repackaged in their own branded shrink wrap. These B-quality cells are then resold for use in low power devices like flashlights where their weaker performance is less http://huntnbike.com an issue. If a cell costs less than $2, it simply isn’t worth it. Stick to the name brand cells, like my favorite Samsung cells, if you want to build a safe, quality ebike battery.

You’ll see two dots where the 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.

“bike batteries -e-bike battery”

Is there same officially recognized method to come up with C ratings? Ping claims 2C on his LiFePo4 batteries, my Chinese-made “BMC” battery claims 3C. Can they just sort of say whatever they want? How do we determine the “real” C rating?

To reach our intended voltage of 36V, we have to connect a number of 18650 cells in series. Lithium-ion battery cells are nominally rated at 3.6 or 3.7V, meaning to reach 36V nominal, we’ll need 10 cells in series. The industry abbreviation for series is ‘s’, so this pack will be known as a “10S pack” or 10 cells in series for a final pack voltage of 36V.

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…

It is also possible in principle to series connect two 36V batteries to make a 72V setup, but the only battery we have that is intrinsically designed for this is our LiGo modules. With all other batteries, it is essential to use a pass diode across the output of each battery so that when one BMS circuit trips it does not get exposed to a large negative voltage. We have a special series battery cable with this diode built in available here.

9S, 32.85VDC, 2890MAH, 94.93WH. THE ENERGY DENSITY OF THESE CELLS ARE SPECTACULAR. YOU GET A POSITIVE AND NEGATIVE LEAD WIRE AND ALSO BALANCE CONNECTORS IF YOU WANT TO BALANCE THE CELLS. IF YOU BUILD …

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.

As a side-note, the Boeing 777 Dreamliner battery fire was using LiCo. They wanted a battery that was as light as possible, and as compact as possible. I am not an engineer, but I agree with the statement made by “Tesla” electric car maker Elon Musk, when he said that there was NOT adequate heat insulation between each cell. Better individual cell insulation would prevent a bad cell that was getting hot from heating up the surrounding cells. That is what led to a domino effect. The Tesla cars have a cell cooling system, and the on-board computer can detect and cut-off any cell-group that is getting hot.

As an aside, the 50A-800A you’re talking about is during the output, and that’s at a very low voltage, which is the reason for the high current draw. But that power equals a much lower current on the input end where it draws from the wall outlet.

Great article! Have ordered everything BUT i have a big problem with the spotwelder. Most homes in europe are limited to 10A and this spotwelder alone drags 15A just to powerupp!!!! I can even start it without blowing both fuses! And when welding it wants 50A-800A which you need a an actual POWERPLANT for!

Oh, one last thing. If you have a poorly formed connector or the wires are fraying, that can increase resistance and cause a voltage drop that might trip a cutoff condition. Just another thing to check for.

BMS (Battery Management System) watch pictures for all technical information. BMS / PCM (reference)16S-40A. Best upgrade Lithium Battery in most compact size (270 ±2) (150 ±2) (90 ±2 ) mm that will fi…

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.

Next, we’ll need to wire multiple 18650 cells in parallel to reach our desired pack capacity. Each of the cells I’m using are rated at 2,900 mAh. I plan to put 3 cells in parallel, for a combined capacity of 2.9Ah x 3 cells = 8.7 Ah. The industry abbreviation for parallel cells is ‘p’, meaning that my final pack configuration is considered a “10S3P pack” with a final specification of 36V 8.7AH.

Lithium electric bike batteries are not cheap, they are not perfect, and they are not readily available. Some OEM’s such as BionX sell a moderately sized lithium e-bike battery pack for $1000 plus. Optibike sells their touring LiPo battery as an add-on accessory for their bike for a gasping $2500. It is surprisingly difficult to find a ready to plug in LiPo battery pack for sale on the internet by any real company.  The reason is simply product liability.

http://www.aliexpress.com/item/SUNKKO-709A-1500W-welding-machine-small-battery-spot-Welder-with-welding-pen-for-18650-pack-welding/32384498157.html?spm=2114.01020208.3.132.T8tjqL&ws_ab_test=searchweb201556_0,searchweb201602_1_10037_10033_507_10032_10020_10017_10021_10022_10009_10008_10018_101_10019,searchweb201603_1&btsid=06a7c525-fb11-425d-8614-730ff4b43d7e

There are two prevalent ideas in pack constructing in these modern days…one is to use larger pouch-like soft cells to construct the pack. The stealthiest battery chemistry by far is LiPo, large cells with power-dense cobalt in the anode chemistry, such as what comes in Hobby King cells. Here is what I mean by “large cell” LiPo. These are soft pouches and large. When you use a pack made of these it will consist of fewer wired together cells than if you use small cylinder cells.

Well, we here at electricbike.com are glad you asked! As of this month (Feb 2013), nobody is selling completed packs with the new NCA chemistry to the public, but the cylindrical cell that will be up to bat next is…

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,

Thanks for your kind words about my article, I’m glad http://electricbikebatterys.com helped! To answer your question, I highly recommend avoiding a custom built charger. While it might be possible to use a DC-DC converter to change the output voltage of your 12V charger, the chances of a problem occurring are too high for my liking. The converter might not be smart enough to adjust the current down once full charge is reached. Technically your BMS should protect your battery from most overcharging scenarios, but if it is overloaded and a component fails, there is nothing to stop your cells from being destroyed.

“build an electric bike battery for electric scooter”

I haven’t seen that exact BMS in the flesh before, so I can’t speak too confidently about it. The description claims it has a balancing feature and so I assume it does, but I’ve also seen BMS that were supposed to have balancing capabilities, but arrived with the balancing components missing from the board.

Gotcha. Can you recommend a manufacturer that sells a two wire version? Maybe I can look around their products and see if they sell any 7S cells, rather than sifting through all the manufacturers on Alibaba. Searches for “2 wire MBS” didn’t yield much. Thanks again for your help with this!

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.

When it comes to layout, there are two ways to assemble cells in straight packs (rectangular packs like I am building). I don’t know if there are industry terms for this, but I call the two methods “offset packing” and “linear packing”.

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

I bought a triangle pack in March 2016…. I reported the issue to EM3ev and they were very concerned. Asked me to do a few tests and it was determined that the battery had a faulty BMS….. They did a replacement pack with upgraded batteries for free….. I …

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 batteries for electric bike balance their packs and constantly monitor the health of their cells.

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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.

Great article! Have ordered everything BUT i have a big problem with the spotwelder. Most homes in europe are limited to 10A and this spotwelder alone drags 15A just to powerupp!!!! I can even start it without blowing both fuses! And when welding it wants 50A-800A which you need a an actual POWERPLANT for!

Why does this formula work? Think about it: heat shrink (unless stated otherwise) usually has a 2:1 shrink ratio, so if I need something with less than twice the circumference (or perimeter rather, since my pack isn’t really a circle) of my pack. Since large diameter heat shrink is quoted in half circumference (flat width) sizes, and I want heat shrink with a circumference of a bit more than the perimeter of my pack, then I know I need the half circumference size to be a bit more than half of my pack’s perimeter, which is equal to the height plus the width of my pack.

The battery cells have now been assembled into a larger 36V pack, but I still have to add a BMS to control the charging and discharging of the pack. The BMS monitors all of the parallel groups in the pack to safely cut off power at the end of charging, balance all the cells identically and keep the pack from being over-discharged.

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

If you are thinking about building your own LiPo pack, a 48V / 10-Ah battery pack can be made for around $300. However to undertake this project you should research extensively on www.endless-sphere.com on how to build and take care of your pack. Expect hours of reading before you are ready to build a pack of your own.

“electric scooter battery |battery scooters”

For BMS’s, the highest quality ones come from a company called BesTechPower but they are more expensive. I have mostly used BMS’s from AliExpress. I’ve linked to a few examples of BMS’s I’ve used in the article above.

The BMS is for 7S, I connect B1+, B2+, B3+, to the negative of the first serie. B4+ is connected to the positive of the first serie, B5+ positive of 2nd serie, B6+ positive of 3rd serie, B7+ positive of 4rd serie.

If you are thinking about building your own LiPo pack, a 48V / 10-Ah battery pack can be made for around $300. However to undertake this project you should research extensively on www.endless-sphere.com on how to build and take care of your pack. Expect hours of reading before you are ready to build a pack of your own.

As an aside, the 50A-800A you’re talking about is during the output, and that’s at a very low voltage, which is the reason for the high current draw. But that power equals a much lower current on the input end where it draws from the wall outlet.

This pattern continues until we’ve got all 10 parallel groups connected. In my case, you can see that the first and last parallel groups aren’t welded on the top side of the pack. That is because they are the “ends” of the pack, or the main positive and negative terminals of the entire 36V pack.

Many people are tempted to use cheaper 18650’s sold under names like Ultrafire, Surefire and Trustfire. Don’t be one of those people. These cells are often marketed as up to 5,000 mAh but struggle to get more than 2,000 mAh. In actuality, these cells are just factory rejects, purchased by companies like Ultrafire and repackaged in their own branded shrink wrap. These B-quality cells are then resold for use in low power devices like flashlights where their weaker performance is less of an issue. If a cell costs less than $2, it simply isn’t worth it. Stick to the name brand cells, like my favorite Samsung cells, if you want to build a safe, quality ebike battery.

Battery Model:36V 12Ah. New Lithium 36 volt 12 amp-hour Battery for Electric Bikes (e-bikes) and Scooters. Life cycle:more than 600 cycles. Battery Size (Approximate): 8″ x 3.75″ x 2.75″. Battery Weig…

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!? 

LiFePO4 is currently widely available for purchase as e-bike packs complete with BMS on ebay and other online merchants. Mostly it is sold by small companies. Also, most of the commercially available e-bikes powered by lithium batteries are using the LiFePO4 chemistry.

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!

Of course, if you go really fast or are pulling an extra load, then this mileage will be worse, like 12-15 wh/km. On the other hand, if you use the motor more sparingly, then you can easily stretch it down to 6-8 wh/km. The table below summarizes the expected range for these different batteries under light, average, and heavy usage paradigms:

First thing is regarding the cells – I have just order some Panasonic 18650PF like yours by chance (I was looking for Samsung). The delivered cells were made and charged in 2014, and the measured voltage now is around 3V (+/- 0.1v). So the voltage is basically the same for all of them but there are old, I think, even thaw never used and stored in a warehouse.

You’ll see two dots where the 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.

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.

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.

A High-performance Motor acheives a top speed of 20-30km/h with a range of 20km means your ebike commute just got easier. Folding style, portable convenient, easy storage. You can lock your bike by ap…

I would not recommend trying to use a 36V charger. The voltage will be way too high and damage either the charger, battery, BMS or all three. Always use a charger that is matched to your pack’s actual charge voltage, which in your case is 22.2V DC.

36v 10Ah Bottle Type Battery. Rated capacity: 10Ah. 36v 14Ah Rear Rack Type Battery. Rated capacity: 14Ah. 48V 14Ah Rear Rack Type Battery. Recommended to be used with 36V 250W electric bicycle motor.

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 http://electrichuntingbikes.com without any flames.

When you buy your battery, make sure you know what its maximum amp output is. Remember, by multiplying amps and voltage you get the actual current capacity of the battery. For example a 48-volt 25 amp pack can put out 1200 watts.

Offset packing results in a shorter pack because the parallel groups are offset by half a cell, taking up part of the space between the cells of the previous parallel group. However, this results in a somewhat wider pack as the offset parallel groups extend to each side by a quarter of a cell more than they would have in linear packing. Offset packing is handy for times where you need to fit the pack into a shorter area (such as the frame triangle) and don’t care about the width penalty.

Ebikeschool.com has a lot of great info, but I’ve spent countless hours putting even more info, examples, how to’s, reviews, maintenance steps and buying guides into my book and video course. They are some of the most fact-dense and info-rich ebike resources available today. So check them out to see if they can help you with your own ebike!

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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.

Lead acid batteries are the least expensive and heaviest battery option. They have a short cycle life if used regularly in deep discharge applications. For electric bikes, the most common setups use 12V bricks of either 7Ah or the larger 12Ah capacities, series connected to form 36V or 48V packs. Because of the Peukert effect, the 7Ah gel cell usually delivers about 4 amp-hours of actual capacity, while the 12Ah lead acid packs will deliver approximately 8 amp-hours. So keep this in mind when comparing a lead acid pack to one of the NiCd, NiMH, or lithium replacements. We do not offer lead acid batteries or chargers, but they are not hard to find.

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.

“build a battery pack _electric car batteries”

After writing my question, I did more research on these cells regarding overcharging and over-discharging and I see where you’re coming from regarding not having connections between the parallel cell blocks to smooth out differences between individual cells. So as a permanent installation, it’s not going to work. However, I’ve had another thought, which I’ve put at the final paragraph.

I haven’t seen that exact BMS in the flesh before, so I can’t speak too confidently about it. The description claims it has a balancing feature and so I assume it does, but I’ve also seen BMS that were supposed to have balancing capabilities, but arrived with the balancing components missing from the board.

I finally made it happen on BMS #3 (the unfortunate thing about AliExpress is that every dumb mistake that kills a part is another month added to the project) and the battery seems to work great, though it only has a couple miles so far.

Most people find that once they have an ebike, they use it for all kinds of applications and trips outide of just commuting, and the ability to go 50+ km on a charge opens up possibilities that wouldn’t have been possible otherwise. Plus, as the battery ages and declines in capacity, it still has more than enough range for your key commuting needs. Imagine if instead of getting an 8Ah pack, you purchased a 15Ah battery. Even if after 4-5 years it has lost 30% of its original capacity, that’s still over 10Ah and leaves plenty of reserve for your 24km commute.

If you are excited about this improvement in battery chemistry, (NCM being 25% smaller/lighter that the fussy LiFePO4, and 300% better C-rate than the reliable and non-fussy LiMnO2) you may also be asking the question…What chemistry is next?

The only two ebike companies that sell LiPo to the public are Optibike and Pi-cycles, and both contain the battery in a strong metal box which makes up of the frame. The companies fire tested these enclosures and are confident that their frame are effective and safe vessels for LiPo storage.

craig it should not damage your controller. When you connect two batteries together in parallel it will actually extend the life of both batteries because you are not taking as much of a toll on them when discharging and hopefully not running them down as low.

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.

Wear gloves. Work gloves, mechanic gloves, welding gloves, even latex gloves – just wear something. High enough voltage can conduct on the surface of your skin, especially if you have even slightly sweaty palms. I’ve felt the tingle enough times to always wear gloves now. In fact, my pair of choice for battery work are some old pink dish gloves. They are thin and provide great dexterity while protecting me from short circuits and sparks.

Thanks so much for all this great informating, Im going to purchase the ebook for sure! One small question first, though. I’m building a 13s8p 18650 pack from laptop batteries for my bfang 750w 25A pedicab. I already have 45V 15 Ah LiPo setups from china, but want to up my Ah.

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I should really change that $2 cutoff to more like $2.50, which is more reasonable for quality cells. Basically, the cheapest ‘good’ cells are Samsung 26F cells, which can be had for usually around $2.50 – $2.90 if you are buying in any large quantity, like at least 100. Expect to pay more like $3.00 or so if you’re buying only 40 cells. 26F cells are also limited to 5A discharge though, so you’ve got the same issue as with the NCR18650B cells from Panasonic.

I like to cut most of my nickel strip in advance so I can just weld straight through without breaking my flow to stop and cut more nickel. I measured out the width of three cells and cut enough nickel strip to weld the top and bottoms of 10 sets of 3 cells, meaning 20 strips of nickel that were each 3 cells wide, plus a couple spares in case I messed anything up.

Choose an electric bike from top brands like Razor, Monster Moto and Jetson, and your child will be burning rubber in no time! In sporty colors like yellow, green and red, your little rider can cruise in style at speeds of up to 15 mph. Adventures can usually last up to 40 minutes, or 10 miles, on a single battery charge. To ensure you get the right bike for your child, carefully examine the age and weight restrictions of your new electric bike.

Oh, one last thing. If you have a poorly formed connector or the wires are fraying, that can increase resistance and cause a voltage drop that might trip a cutoff condition. Just another thing to check for.

When it comes to welding your parallel groups in series, you’ll have to plan out the welds based on your welder’s physical limits. The stubby arms on my welder can only reach about two rows of cells deep, meaning I will need to add a single parallel group at a time, weld it, then add another one. If you have handheld welding probes then you could theoretically weld up your whole pack at once.

I’ve gotten so many different BMS’s from so many different suppliers so I’m not 100% positive, but I believe it was from this source: http://www.aliexpress.com/item/NEW-Battery-Protection-BMS-PCB-Board-for-10-Packs-36V-Li-ion-Cell-max-30A-w/32291193643.html

I need to build a 56-60v battery that I will be using to convert a bike with 20″ moped rims and a 48v 1500w 46.5 kmh — 28.8mph 13 * 5T winding rotor hub motor. I’m looking more for range than speed (mostly flat where I live), although I would like to top 30mph. If my math is right, in order to accomplish this I need to build a pattern that is 16s6-8p. Which 18650 cells should I choose? I’m also not sure which BMS I should use? And then which controller is best for this battery and motor setup? I’ll post the links to the parts I’m currently sourcing and let me know if you think there is a better set up or parts. Thank you

Hi Micah,I am from INDIA want to construct a 36v,15 ah,peak current 15 amp,continuous current 6 to 8 amps. Now ipurchased 20 pcs new IFR 18650 lifepo4 rechargeable cells,and a BMS36v,lifepo4 BMS12s forE.Bike lithium battery pack 12s,36,v,PCm.How many cells total i have to use for my aim?What kind of charger (specification) i have to purchase? Your article and reply to questions are interesting.please guide me.

An older battery technology that was popular around 10 years ago as replacment for lead acid in some more expensive commercially available e-bikes. Today it has been obsoleted  in e-bike applications because of the recent availability of LiPo and LiFePO4 cells. NiMH is a finicky technology to deal with. The packs do not have long life expectancy, and have to be treated delicately. One big problem for DIYers is that its very hard to safely charge NiMh cells that have been soldered together in parallel. Extra care is needed for NiMH in both assembling and charging.

It makes very little difference whether you have a small geared motor, a large direct drive motor, or a mid-drive motor. The mileage and range figures for a given battery have to do with how you use the ebike, not which motor system is on the bike.

Thanks so much for the info, that sounds great and an exciting option! I understand the warranty issue but aside from that, you don’t see any issue than with building a battery of any capacity and just making the discharge cable with an xlr connection to plug into the bike. Would I need a different cable to charge the battery or does it charge via the xlr connection like theirs? Here is one more link with a few more answered questions about their auxiliary battery if you wanted more info. Thanks again, this is really exciting, I just want to make sure I don’t fry anything

The exact amount of range you’ll get per battery and motor varies greatly and depends on factors like terrain, speed, weight, etc. Suffice it to say though that if you double your current battery capacity, you’ll see an approximate doubling https://en.wikipedia.org/wiki/Electric_bikes your range as well.

As an aside, the 50A-800A you’re talking about is during the output, and that’s at a very low voltage, which is the reason for the high current draw. But that power equals a much lower current on the input end where it draws from the wall outlet.

Hey, I’m about to build my 16S2P pack from 32 Samsung INR18650-25R cells bought from batterybro.com. How far apart can their voltages be when you connect the parallel packs? They seem to all be charged between 3.52V and 3.56V.

The higher C-rate of 3C for the newer LiFePO4 (from A123) keeps these popular so you don’t need a huge pack to get fairly adequate amps. To get a continuous 24A, you’d only need a 8-Ah battery. Fairly affordable, and small enough to fit in a bike frame.

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

192 watt-hours is about the smallest battery size you would want for an ebike. Many of the store-bought ebikes have about this much capacity since it keeps the battery cost down. For people who want to actually commute reasonable distances of 40-50km, then I would recommend on the order of 400 watt-hours. While it can vary a lot with usage habits, an energy consumption of 9-10 watt-hrs / km is typical on normal direct-drive setups.

Another disadvantage of lead acid batteries is the shorter lifespan. Most claim to be rated for over 200 cycles, but in practice I usually find many SLAs start showing their age at around 100 cycles. They’ll still work as they get up in years (or charge cycles), but you’ll begin seeing your range quickly decreasing. If you were traveling 15 miles per charge when the SLAs were new, a year later you could find yourself barely getting past 10 miles.

“bicycle battery kit _lithium ion battery bike”

Specifically, battery packs are made up from many cells: the lead acid ones are similar to those we use on our cars, while the lithium ones use the same technology as mobile phones. Apart from the chemical component inside their cells, the main feature that differentiates lead acid and lithium batteries is their size: the lead ones are heavy and have a short life (200 to 300 charge cycles), while the lithium ones are smaller and can last longer (from 500 to 1,000 charge cycles).

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“

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.

However… I’m thinking about extending the range of my 250W ebike (a Greenedge CS2) by wiring a battery in parallel as a one-off project. My thinking is that as it would halve the load on each of the batteries, it would reduce output current and voltage drop under load. This I’m thinking would allow use of a simpler constructions, since the stress on https://en.wikipedia.org/wiki/Electric_bikes cell would be reduced.

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.

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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?

I also don’t have a spot welder, and for the purpose of building a single 16S2P pack, I’m not sure I want to splurge on that extra $100+. I do have a whole tub of flux and a temperature-controlled soldering iron, so I’ll be attempting to solder the cells instead (extra hot and fast with lots of flux to avoid conducting too much heat into the battery internals from dwell time).

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. 

That’s a tough one to answer. It depends on the power of the battery (typically 24, 36 or 48V), the power of the bike (limited in the UK to 250W), the bike’s battery management system, and the way you ride. Some bikes allow you to choose different levels of assist to prioritise speed or battery life, which makes predictions of battery life even more difficult.

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?

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 can’t find the exact same battery to fit in that holder, you could aways open up the area where the controller is and lengthen the wires so they exit the case, then put your own connector there (rated for at least 20A). Then add that same connector to your second battery pack and you’ve got an easy plug and play setup for switching packs with the matching connector.

The battery maximum power = volts x amps, so if this 36V battery can deliver 30A continuous, that means it can deliver a maximum of 1,080 watts, though I would run it conservatively at a lower power level than that in most applications.

Regarding your first question: as long as your BMS has a balancing function (most do) then you do NOT need a charger that does balancing, and in fact you should not use one. The BMS takes care of all the balancing, so all you need is a simple ebike charger. What is important though is that it is a CC-CV (constant current, constant voltage) charger. Most ebike chargers are, but just check to make sure it says that somewhere in the description, or ask the vendor if you can’t find it. The CC-CV part means that the charger will supply a constant current first, bringing the battery voltage up slowly until it reaches the full voltage (54.6V for your 13S battery). Then it switches to CV mode and holds a constant voltage while it gradually backs the current down to zero, which is the ‘finishing’ part of the charge.

Battery Model:36V 12Ah. New Lithium 36 volt 12 amp-hour Battery for Electric Bikes (e-bikes) and Scooters. Life cycle:more than 600 cycles. Battery Size (Approximate): 8″ x 3.75″ x 2.75″. Battery Weig…

192 watt-hours is about the smallest battery size you would want for an ebike. Many of the store-bought ebikes have about this much capacity since it keeps the battery cost down. For people who want to actually commute reasonable distances of 40-50km, then I would recommend on the order of 400 watt-hours. While it can vary a lot with usage habits, an energy consumption of 9-10 watt-hrs / km is typical on normal direct-drive setups.

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.

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).

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!):

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.

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]

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.

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.

36v 10Ah Bottle Type Battery. Rated capacity: 10Ah. 36v 14Ah Rear Rack Type Battery. Rated capacity: 14Ah. 48V 14Ah Rear Rack Type Battery. Recommended to be used with 36V 250W electric bicycle motor.

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?

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…

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…

LiFePo is 30 to 50% heavier and 10-20% more expensive than LiMn/LiNiCoMn. It’s safe but mainly, it’s got at least double the cycle life of LiMn/LiNiCoMn and seems to have an almost indefinite shelf life.

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.

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.

I’m glad you enjoyed the article. To answer your questions: I chose this type of battery instead of LiFePO4 mostly because of the cost and convenience. LiFePO4 is a bit more expensive and has fewer options for cells. These Li-ion cells are a bit less expensive and there are dozens of options with many different specifications for any power/capacity need. I’ve used and built LiFePO4 packs before and they have their own unique advantages, but for me they just don’t add up to enough.

Thanks so much for this excellent information. I was wondering how to calculate the total amps for the entire battery? I’m trying to determine watts from this as I have a 24V 500 watt Rayos electric bike and am working to build a 24V 20 Ah battery (7s7p) battery and would like to know what watts it is capable of providing.

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.

“replacement battery for electric scooter panasonic 18650 cells”

When it comes to welding your parallel groups in series, you’ll have to plan out the welds based on your welder’s physical limits. The stubby arms on my welder can only reach about two rows of cells deep, meaning I will need to add a single parallel group at a time, weld it, then add another one. If you have handheld welding probes then you could theoretically weld up your whole pack at once.

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?

Something that’s worthy of note, is that “AllCell” is using a block of graphite/wax composite Phase-Change-Material (PCM) using a patented formula. If a single cell suddenly starts running hot, the heat is instantly spread out across the PCM block, which would prevent a thermal runaway event. According to a recent press-release:

7. Winner selection and notification: Winners of the Sweepstakes will be selected in a random drawing under the supervision of the Sponsor. Winners will be notified via e-mail to the e-mail address they entered the Sweepstakes with within five (5) days following the winner selection. Electric Bike Technologies LLC shall have no liability for a winner’s failure to receive notices due to winners’ spam, junk e-mail or other security settings or for winners’ provision of incorrect or otherwise non-functioning contact information. If the selected winner cannot be contacted, is ineligible, fails to claim the prize within 15 days from the time award notification was sent, or fails to timely return a completed and executed declaration and releases as required, prize may be forfeited and an alternate winner selected. The receipt by winner of the prize offered in this Sweepstakes is conditioned upon compliance with any and all federal and state laws and regulations. ANY VIOLATION OF THESE OFFICIAL RULES BY ANY WINNER (AT SPONSOR’S SOLE DISCRETION) WILL RESULT IN SUCH WINNER’S DISQUALIFICATION AS WINNER OF THE SWEEPSTAKES AND ALL PRIVILEGES AS WINNER WILL BE IMMEDIATELY TERMINATED.

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.

Is it possible that the controller for this Rayos 600W (sorry thought it was 500W but it’s actually 600W) is inside the electric motor itself? I traced all wiring on the E bike but find no controller anywhere. Do you see anything majorly wrong with using a BMS to charge the cells but not discharge, as in sending the current from the battery directly to the controller / motor? I’ve been unable to find a BMS that can do 30A that isn’t very expensive. A side note, I was able to test amperage while riding and around 20A gets me 9 miles per hour, that is where my multimeter tops out! I’m 235 pounds. I’m guessing I need around 30A to get the 16 MPH I get now with the existing LiFePO4 battery pack.

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.

Ideally, I would buy a battery with the same type of connection and just carry the spare one unconnected and swap them over but I don’t seem to be able to find the type of battery case for sale anywhere. It’s a quick release bottle type battery that has two sprung terminals about half inch in diameter that contact with two large terminals on what I think must be the motor controller integrated into the bottom of the bottle mounting bracket.

I finally made it happen on BMS #3 (the unfortunate thing about AliExpress is that every dumb mistake that kills a part is another month added to the project) and the battery seems to work great, though it only has a couple miles so far.

You mentioned that you made a discharger from halogens. Is there any reason not to just use a couple power resistors in parallel, like 2×25 ohm, 100w for a 13s6p pack? Do you know why it’s helpful to take it easy on the pack for the first couple cycles?

I see, so regarding the question about building backup batteries, applications where the existing backups are NiMH or NiCd and are already designed into a charging system should really get NiMH replacements rather than Li-ion. I didn’t realize older batteries used something other than CC-CV.

Another advantage of lead acid batteries is their high power output potential. Lithium batteries generally don’t like to handle too much current. SLAs, on the other hand, can provide huge amounts of current. If you are planning a very high power electric bicycles, SLAs might be a good option for you.

For discharge wires you’ll want something bigger, like 14 awg http://huntneqip.com wire. 12 awg would be better but might be overkill for your use. For charge wires, 16 awg silicone wire would be fine and you could probably get away with 18 awg silicone wire.

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…

Update: it looks like my nickel strips might be pure nickel after all. The salt water appears to have a suspension of brown precipitate which looks and smells like rust. However, after fishing the nickel strip out and rinsing it with water, it still appears to be silver in colour and not rusted:

The sense wires generally connect to the positive of each cell group, but sometimes there is one more sense wire than parallel groups because the first sense wire is intended to connect to the negative of the first cell group, then all the subsequent sense wires connect to the positive of each cell group. Each BMS should be labeled on the board to show where each sense wire goes (B1-, B1+, B2+, B3+, etc…)

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.

However… I’m thinking about extending the range of my 250W ebike (a Greenedge CS2) by wiring a battery in parallel as a one-off project. My thinking is that as it would halve the load on each of the batteries, it would reduce output current and voltage drop under load. This I’m thinking would allow use of a simpler constructions, since the stress on each cell would be reduced.

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.