“battery bicycle +electric moped battery”

Charge current depends on the cells. Most cells can take at least 500mA, some considerably more. It’s hard to know what cells you’re using. Assuming they are 18650pf Panasonic cells like I used here, 1A per cell would be fine, giving you a charge rate of 3A. They can actually take more than that, but there’s no reason to push them too hard if you don’t have to.

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!? 

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:

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.

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Yes, as I understand it, Nimh and NiCd batteries charge differently. I understand lithium batteries much better than those other technologies, so don’t quote me on this, but I believe that Nimh and NiCd cells have current powered through them and the voltage control is different, as opposed to lithium cells that draw current at the charger’s preset rate and then keep drawing until the voltage floats to 4.2V, at which point the already tapering charger’s current supply is cutoff and the battery is fully charged.

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.

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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 http://electricbikecharger.com they are rated higher so you can fit a 20A fuse in a 10A slot, for safety.

When it comes to buying your cells, you might be able to find a local source, or you can order them straight from Asia. I prefer the second option, as you’ll usually get a much better price going straight to the source, even when paying for international shipping. One caveat though: do your best to ensure that your source sells genuine cells and not knock-offs. Do this by checking feedback and using a payment method that ensures you can get your money back if the product isn’t as described. For this reason, I like to buy my cells on Alibaba.com and AliExpress.com.

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.

This is also why the common and affordable RC smart-chargers are powered by a separate DC power supply. Many RC enthusiasts spend a day at a park, and while flying an RC plane, they have several other battery packs that are charging from their cars 12V system.

I’m planning on building a 10S12P pack for usage on a custom DPV (Diver Propulsion Vehicle). For packaging purposes, it would be best for me to split the battery pack in several battery modules instead of a single block of cells.

1. The extra amperage that the battery could output isn’t wasted, it’s just sort of a safety factor. It means you aren’t stressing the battery to its limit. Also, batteries only get their full rated capacity at lower discharged. So you’re more likely to get the full capacity now than if you actually pulled 50A out of it.

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The battery packs from Allcell are unique in that the cells are surrounded in a phase change material supported in a graphite matrix, which allows these batteries to handle higher sustained discharge currents without the cells overheating, and they have longer cycle life as a result of this thermal management. However, being ‘naked’ packs, they do not come in a rigid enclosure or bike mounting solution, The 48V 23Ah packs now come in a very nice rigid casing, though they still do not have ane explicit mounting mounting hardware and it’s up to the user to install them in protective case or bag on the bike. These batteries are available in 36V 17Ah, 36V 23Ah, 48V 17Ah, and 48V 23Ah options, and can handle 40A motor controllers just fine. They are assembled in the USA and have UN38.3 certification.

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.

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Just kidding, here’s a little more detail. 1) Yes, actually you could just use one strip of nickel on series connections to make the electrical connection, but one strip of 0.15mm thick nickel strip can only safely carry less than 10A. Ideally you want at least one strip for every 5-7A you plan to pull through the battery. 2) You can definitely do the series connections first, it is just habit for me to do parallel connections first. Also, on larger packs I like to do parallel groups first and then glue them together and do the series connections as I glue each group. 3) People have explored this idea a bit on Endless Sphere, and while it can be done, it has a lot of room for error, mostly in keeping the spring loaded contacts permanently against the cell terminals and in keeping the contacts from corroding. Spot welding is the best method, in my opinion.

Most inexpensive NiMH packs are not really designed for discharges greater than 1C. That batteries for electric scooter that if your ebike draws 15 amps on average, you would want a pack that has a capacity on the order of 15 amp-hours more.

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).

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.

If those are new cells then I’m surprised that the voltages aren’t identical. That difference (0.08V) is about the farthest difference I’d want to see between cells. Ideally you should charge that 3.82V cell up a bit more before you connect it in parallel with the others. I’d run tests on all of those cells though with a capacity tester to ensure they are good quality cells though. Genuine cells straight from the factory should all have identical voltages.

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.

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 …

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.

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. 

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.

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“scooter batteries 36v battery for electric bicycle”

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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:

You’ll also notice in the following pictures that my charge and discharge wires are taped off at the ends with electrical tape. This is to keep them from accidentally coming in contact with each other and short circuiting the pack. A friend of mine recently tipped me off to another (and probably better) option to prevent shorts: add your connectors to the wires first, then solder them onto the pack and BMS. Doh!

thanks for detail explanation , I was enjoj reading it. Well, I am interesting why did you pick this tipe of battery, I was thinking to use LiFePO4, I know there are usualy 3.2V it is less than 3.6V like here? Also, can you explain me how to calculate max current of battery, it says that you get 8.7Ah, but how much Ampers and what is the power of battery, how many Watts (P = U * I)? Furthermore, without welding, can I do on contact connection, like for example are battery in remote control?

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!

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.

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My thinking is that because each of the batteries is only 50% stressed, that the probability of problems due to overcurrent, etc. would be negated and I wouldn’t use a BMS for the supplementary battery.

So let say main point to count the power is to count the power is to know what type of the controller i have (i have check my batt connection goes to PCB which has sensors it self and whole unicycle controller… ) how to know ? Or in primitive way i can count like my batt is 20A and 36W so max power can be 720W but its peak on continues?

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.

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.

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 you can fit onto the trailer.

The Panasonic NCR18650PD cells can be purchased at Fast Tech dot Com, who reliably processed and shipped my transaction. Good prices, too, from this Chinese-based vendor. I “tested the waters” by buying just 4 cells first and will certainly be buying more from them. I’d like to make my own e-bike pack with these cells and further inquired to AllCell to see if I could obtain one of their PCM blocks. Unfortunately, they will only sell these on bulk wholesale basis to established pack-building businesses. The DIY pack builder will have to explore other options.

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.

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?

Hailong makes some of the more refined of the generic battery enclosures from china. You’ll see them online everywhere, stuffed with whatever cells and BMS circuit appropriate to the market being addressed. They secure to the water bottle eyelets on the down tube of your bike frame, and the narrow height of this pack design allows it to fit even on smaller or hybrid frame geometries that wouldn’t normally fit a pack. We have the smaller Hailong-01 enclosure in 36V (10s 5p) and 52V (14s 4p) layouts suitable for 20-25A current setups, and the larger Hailong-03 enclsoure in 36V 23.5Ah (10s 7p) and 52V 16.5Ah(14s 5p) sizes for higher current and capacity. 

Do you think it is the BMS or the controller that is cutting out beyond a certain load or something else completely? As far as I am aware the battery is fully charged and balanced (I even left it charging for 2 days once as I read that it can sometimes take this long to balance the cells!).

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.

Now I’m sure you’re all jazzed about building your own battery pack. But just in case, I’m going to leave you with an awesome video featuring battery builder Damian Rene of Madrid, Spain building a very large, very professionally constructed 48V 42AH battery pack from 18650 cells. You can read about how he built this battery here. (Also, note in the video his good use of safety equipment!)

LiPo’s are the smallest, cheapest, lightest and most powerful lithium batteries. Their disadvantages include short lifespan and propensity to combust into giant fireballs if not cared for correctly (I’m not kidding, check out the short video clip below).

Because of problems with quality and weight, lead acid batteries are not common in the rest of the world. In Europe, for example, acid lead batteries represent less then one per cent of the total; while 96.5 per cent is taken by Li-Ion and two per cent by LiPo (source: Greenfinder market report).

Here is a an example of a large format soft pouch LiPo pack with 13 cells, and a BMS. This pack was built using cobalt LiPo soft cells with a BMS from a Chinese factory for an electric bike. You can see the top cell has been squished, causing the cell to fail and the BMS to shut down the battery, and not allowing it to charge or discharge. This pack is small and light (7lbs).  This $500 pack is now ruined, but  all is not lost since it did not start a fire, and it did NOT take the house with it.

hello sir. nice guide FOR battery pack li-ion… i will try an electric bike kit for my 26″ MTB. and buy 1000w hub motor kit. i can solve my battery problem (expensive you know) with li ion pack. i have some questions,

Sorry Benoit, but that won’t work. The BMS will expect the full 10 cells and when it sees that cells are missing, it will assume they are at 0V and not provide any power. You need a 7s BMS, which are pretty commong. 8s will be harder to find for li-ion, but you could do 8s with LiFePO4 and those 8s BMS’s are common.

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.

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!

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:

Rechargeable Electric Bicycle Batteries 48V 20AH Lithium Ion Battery. These are 18650 cell based batteries (similar 18650 type cells are used in the Tesla car). Use it for ebike, scooter etrikes. Batt…

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.

If you want to learn more in-depth about building your own lithium battery, you’ll want to check out my book “DIY Lithium Batteries: How To Build Your Own Battery Packs” which is an Amazon #1 Bestseller in multiple categories!

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.

A big downside of lithium batteries is that they are much more expensive than lead acid batteries. Prices batteries for electric scooters replacement 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.

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.

Lithium batteries made specially for ebikes often come with specific bicycle mounting points making them easy to bolt to the bike frame, seat post or rear rack. If you go with a different type of lithium battery without ebike specific mounts, you’ll likely have to put it in a bag on the bike, which is still a good option, and one that I even prefer sometimes. (Link to blog post of mine about center frame triangle batteries).

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Almost all consumer electronics that have a plug-in charger these days are powered with lithium batteries because they can store about 3 times more energy than NiMH. Small devices like cell phones, mp3 players, and other gadgets typically have lithium-polymer packs, as these can be formed in conveniently shaped thin rectangular pouches. Larger devices like laptops and the new lithium cordless power tools generally use cylindrical Lithium-ion cells of a size smaller than a ‘C’ but bigger than a ‘AA’. These are spot welded in series/parallel combination to give an appropriate voltage and capacity for the job.

It’s always hard to say exactly how much AH’s someone will need because every case is different. With that powerful motor sucking lots of juice and big hills though, you are going to want a minimum of 48V20AH. If I were you I would try to go even higher, but it may be even better to simply have two batteries at that point. It’s annoying to swap them, but if you ever had a problem with a 48V30AH battery that destroyed the pack, it would be a big investment straight to the garbage. A problem in one of your smaller packs would mean you still had the other. It’s not likely to happen, but it’s something to think about.

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

A High-performance Motor acheives a top speed of 20-30km/h with a range of 20km means your ebike commute just got easier. Power: Under 500W. Load capacity: under 200KG. Material: Aluminum Alloy. Outdo…

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.

Remove all metallic jewelry. This is another tip that I can give from experience. Arcing the contacts on your battery is not something you want to happen ever, and especially not against your bare skin. I’ve had it happen on my wedding ring and once even had a burn mark in the shape of my watch’s clasp on my wrist for a week. Now I take everything off.

RC motors and RC batteries used what E-bikers considered to be fairly lower voltages (14V-22V), which RC enthusiasts needed in order to keep the batteries small in the compact RC planes. The number of E-bikes outside of China is low compared to the the number of global RC products. People who would never ride a bicycle under any circumstances might have several expensive RC models. Since RC components were designed to use lower voltages, the users tweaked their systems to draw more amps for better performance. RC buyers didn’t care about the occasional fire (a rare event), they wanted higher-amp batteries.

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?

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.

Thanks for the info! I http://huntnbike.com read about builders that used Sony Konion LiMn cells that were removed from Makita Drill packs. The constant theme of their reports show that the thing they seem to like the most, is that the cells seem to just stay in balance. So much so that, several have built packs with no BMS. If there is a measurable LiMn shelf life issue compared to other chemistries, it doesn’t seem to bother the DIY pack building crowd.

As you draw current from a battery pack, the voltage will very slowly decrease until the cells start to go flat and then the voltage will plummet. The time that the battery lasts for is directly related to its capacity, measured in amp-hours (Ah). A pack that can deliver 1 amp for 1 hour has a capacity of 1 Ah. Most ebike batteries are on the order of 10 amp-hours. Suppose your bike uses 15 amps on average and has a 10Ah pack, then you would expect it to last for – quick, mental calculation… – 40 minutes.

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.

Since you mentioned the charger, the link you sent me came with a 2 amp charger but it would take 10 hours to charge that size battery. Could I use a larger amp charger like 5 or even more for faster charging? How do you tell what is too much so you don’t damage the battery? Thanks!!

Lithium batteries are not 100% fire-safe. Some batteries are more dangerous than others, depending on the chemistry, whether it has BMS or not, and what kind of casing the battery is in. If the battery is cased in metal its less likely to burn your garage down, than if its encased in plastic. Also be aware that all BMS’s are not alike, some are good and others are crap, just like anything else in life.

You can also add a label or other information to the outside of your pack for that professional look. If nothing else, it’s a good idea to at least write on the pack what the voltage and capacity is. Especially if you make multiple custom batteries, that will ensure you never forget what the correct charge voltage for the pack is.

Thank you so much for taking the time to write the battery chemistry article. I am looking at buying my first electric bike, and needed to understand the differences in LiOn batteries. There are still retailers selling SLA battery pack bikes and wasn’t sure if that was what I wanted, or LiOn. Your article helped me greatly.

Why do we alternate sides of the pack during the welding process? We do it because in this way we connect the positive terminal of each parallel group to the negative terminal of the next group in line. That’s how series connections work: always positive to negative to positive to negative, alternating between the two.

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.

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.

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!

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 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?

The battery’s placement on the bike depends on different factors, especially the shape of the bike’s frame. Most electric city bikes (more than a half) will have the battery mounted on the carrier rack, while mountain bikes usually have them on the down tube.

I would like to know what input in terms of voltage and current i should provide to my battery of 36V 8.7AH. And also how the calculation goes if i want to build a battery for some other Voltage and current specification ?

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 …

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?

I didn’t include a charging a section in this article, as this was just about how to build a lithium battery. But here’s a video I made showing you how to choose the appropriate charger for your lithium battery.

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.

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.

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.

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

eBay determines trending price through a machine learned model of the product’s sale prices within the last 90 days. “New” refers to a brand-new, unused, unopened, undamaged item, and “Used” refers to an item that has been used previously.

Typically you can expect somewhere between 25 and 70 miles of travel on a single charge of an ebike. If you’re riding hard on full power expect less; manage your battery life well and you could get more.

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I finished an ebike yesterday, but i found some major problems on it, The problem is while i riding the bike by throttling, some times the display light dims and low battery voltage caution icon is displaying in the display. and than display shutting off. after that if i try to turn it on again it wont work, so i removed the battery from controller and installed it again than works perfectly, it happens always so i want to remove and install battery again and again, so what is this problem, is this problem is in battery or controller?? Please give me a solution.

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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 batteries for e bikes be charged between 3.52V and 3.56V.

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.

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?

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.

Do you think it is the BMS or the controller that is cutting out beyond a certain load or something else completely? As far as I am aware the battery is fully charged and balanced (I even left it charging for 2 days once as I read that it can sometimes take this long to balance the cells!).

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.

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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?

What a great article! It has opened my eyes to lots of possibilities. Being new to this I had a couple of questions. I am interested in building a spare battery to give me more range on the Faraday Porteur. My question is how to connect the battery I would build to the bike. The main battery resides in the downtube and the connection is hidden. They offer an ancillary battery that plugs into the charging port which is what I would like to build myself rather than buy. Do you think this would be possible? Where could I find a connector that would match? Any concerns? If so, what other options do you suggest? Thanks so much for the help!!

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When it comes to choosing a BMS, the number of cells you have in parallel aren’t important. Only the number of series cells matters. The same BMS will work with 1 or 100 cells in parallel, as the voltage stays the same regardless of the number of parallel cells.

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 are 18-19Ah.

We sell roughly equal numbers of 36V and 48V battery packs, and all of our conversion kits and controllers work fine with both 36V and 48V (or 52V) battery options. Just because 48V is a larger number, it does not mean that a 48V ebike is intrinsically better / more powerful / faster than a 36V ebike despite what the ill-informed internet will lead you to believe. However, it is true that a given motor will spin faster at a higher voltage, and usually higher speeds will correspond to more power consumption. For most of the stock hub motor kits that we offer, a 36V battery will result in a commuting speed of 30-35 kph, while wth a 48V battery will result in closer to 40-45 kph.

hello, firstly i would like to say that i think this is a brilliant article its really helped me understand a lot more about how this works and how i can use a similar system for my project but i am a little confused and i was hoping to pick your brains….

I guess I’ll just have to risk some deterioration on the cells. I don’t think there’s much of an effect, as I did it on an old 18650 cell to test. The joint and surrounding areas were cool to the touch within 1-2s of removing the heat.

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 batteries can be paralleled at any charge level as long as they are all the SAME charge level, i.e. same voltage. If they are all 3.81 V then you can parallel them, or you can charge them all to 4.2V and then parallel them, both are fine options. But if you are putting many parallel groups in series then it is a good idea to get them all to the same charge level first. That will make the first charge of the whole pack much easier as the BMS doesn’t have to balance cell groups that are at very different charge levels.

Yes, as I understand it, Nimh and NiCd batteries charge differently. I understand lithium batteries much better than those other technologies, so don’t quote me on this, but I believe that Nimh and NiCd cells have current powered through them and the voltage control is different, as opposed to lithium cells that draw current at the charger’s preset rate and then keep drawing until the voltage floats to 4.2V, at which point the already tapering charger’s current supply is cutoff and the battery is fully charged.

I think it is much better to use a purpose built CV-CC (constant voltage, constant current) ebike charger. I 100% understand the desire to complete the project on the cheap, but I think that sometimes it is worth a few extra bucks as insurance to protect your battery which is worth many hundreds of dollars.

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.

Either way works, but my orange jig saves me one hot glue step which just makes for a cleaner looking pack. Of course it’s all the same after the pack gets covered with shrink wrap, so you can use any method you’d like. I’ve even found that some of those cylindrical ice cube trays are perfectly sized to hold 18650 cells. Cutting off the top would leave it clear for welding. I’d add some strong neodymium magnets to the backside to hold the cells in place like my orange jig has, but other than that it’s a perfect jig almost as-is.

Lithium batteries are not 100% fire-safe. Some batteries are more dangerous than others, depending on the chemistry, whether it has BMS or not, and what kind of casing the battery is in. If the battery is cased in metal its less likely to burn your garage down, than if its encased in plastic. Also be aware that all BMS’s are not alike, some are good and others are crap, just like anything else in life.

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Use 52v20 in place of 48v20 to get more speed New! Rechargeable Electric Bicycle Batteries 52V 20AH Lithium Ion PVC Battery. These are 18650 cell based batteries (similar 18650 type cells are used in …

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.

There are many different types of 18650 cells out there to choose from. I prefer to use name brand cells from companies like Panasonic, Samsung, Sony and LG. These cells have well documented performance characteristics and come from reputable factories with excellent quality control standards. Name brand 18650’s cost a bit more, but trust me, they are worth it. A great entry-level cell is the Samsung ICR18650-26F cell. These 2,600 mAh cells should cost somewhere around $3-$4 in any decent quantity and can handle up to 2C continuous discharge (5.2 A continuous per cell). I get my Samsung 26F cells from Aliexpress, usually from this seller but sometimes I’ve seen a better price here.

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.

HERE ARE 100 GENIUNE LG LGDAS31865 18650 2200MAH CELLS. YOU CAN’T FIND A BETTER DEAL THAN THIS. Capacity: 2200mAh. THE PHOTOS SHOW HOW WE GET THESE IN AND BREAK THEM DOWN. STOP GETTING RIPPED OFF AND …

Capacity: 20Ah. 36V 3A Charger. Lifecycle of single cell: >85% capacity after 1500 cycles, > 70% capacity after 3000 cycles. (<1C discharge rate and <1C charge rate). It will take about 7 hours to cha... Here is a an example of a large format soft pouch LiPo pack with 13 cells, and a BMS. This pack was built using cobalt LiPo soft cells with a BMS from a Chinese factory for an electric bike. You can see the top cell has been squished, causing the cell to fail and the BMS to shut down the battery, and not allowing it to charge or discharge. This pack is small and light (7lbs).  This $500 pack is now ruined, but  all is not lost since it did not start a fire, and it did NOT take the house with it. These lists, updated hourly, contain bestselling items. Here you can discover the best Adult Electric Bicycles in Amazon Best Sellers, and find the top 100 most popular Amazon Adult Electric Bicycles. 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? 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. 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. For this reason I like to either add a second lock specifically through the handle of my lithium battery (if it’s a removable style battery) or permanently secure it to the bike so it isn’t removable at all. The second option is less convenient because it means you have to bring the charger to the ebike, but it’s a much more secure option if you find yourself locking your ebike in public often. The lithium iron phosphate (LiFePO4) battery has had a lot of hype and media attention lately. This is the same chemistry used by A123 in the Dewalt power tool battery packs, where it has a 2000 charge and discharge cycle warrantee and has phenomenal current handling capability. The LiFePO4 batteries sold for ebike use generally have much lower current ratings, and the actual number of charge and discharge cycles that these generic packs will provide remains to be seen, although most manufacturers seem happy to claim 1500 to 2000 cycles. Iron Phosphate lithium packs are only slightly lighter than NiMH and a fair bit more expensive, but they could be the most economical in the long run. 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! 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... 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. I’ve been building a 13s6p Li-ion battery based on your article, and everything went swimmingly (except underestimating the amount of nickel I’d need) until I started hooking up the BMS. I was in the middle of hooking up the sense lines, and the BMS smoked. Opening it up, it looks like a few of the caps that couple adjacent nodes burned. Have you seen this before? Any thoughts on what I may have done wrong, or does this just happen sometimes when a cap’s voltage tolerance is outside spec? Sizing a bike correctly is important for pedaling efficiency and safety. Fitting a bike involves many factors. However, the basic considerations before buying a bike include frame size, seat height, and... C values seem to be as much about cell packaging as chemistry for LiFePo/LiMn/LiNiCoMn Pouch and prismatic cells with high AHr per cell tend to have a C value of about 1 to 1.5. So cheap packs both cased and shrink wrapped or from suppliers like Ping seem to be like this. Cylindrical cells from A123 or Headway tend to have C values of 3C to 5C upwards. And for a fully built pack, C is as much about cells in parallel as anything. eg 10s2p having twice the C of 10s1p Again BMSBattery/GreenBikeKit are now selling LiFePo Headway based packs with a BMS and with C values of 3C to 5C and either cased or shrinkwrap. 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! 10. 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Pedals: Foldable. 26\” wheels with Aluminum Alloy spokes. Opportunity: Outdoor Camping, Mountain. 36V 8AH Lithium-Ion Battery. Material: Aluminum Alloy. Wheel diameter: Approx. Head height (To ground)…

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…

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 just have a simple question: I would like to replace the Nicad battery 24V / 5Ah of my old Yamaha PAS XPC26 with a 7s3p and maybe try a 8s3p for something more “punchy” (hoping the controller will not burn …) . Do you think I can buy a 10s BMS and use it with a 7s or 8s battery? In this case, what should I do with the spare balance wires ?

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…

Sure, it is possible to solder directly to the cells (though it can be tricky without the right tools). The problem with soldering is that you add a lot of heat to the cell and it doesn’t dissipate very quickly. This speeds up a chemical reaction in the cell which robs the cell of its performance. The result is a cell that delivers less capacity and dies an earlier life.

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.

Excellent, excellent, excellent (did I mention excellent) motor! So much fun, so much torque. I bought mine with 30q 52v battery, unbelievable power. Done about 300 km yet but absolutely no regrets. Get the 42 teeth Lekkie ring, makes worlds of difference. The new color display is also …

“lithium bike battery +build an electric bike”

Furthermore, if you have more capacity than required, then you also have the opportunity to do partial charging of the battery with a Satiator or similar device, so that instead of charging the pack to 100% to squeeze out every km, your standard charge is set to a lower 80 or 90% level. This can have a pronounced effect increasing  both the cycle life and calendar life of a lithium battery by several fold. 

It’s best to try and match the cells as closely as possible based on capacity by using a lithium cell tester like this one. If you plan on using the battery you build for a high drain application, different current ratings will be more of an issue. If you have many cells in parallel and will only pull low current from each one, then different current ratings are less of an issue. It’s always best to use perfectly matched cells, though I know that’s not the cheapest option and is outside of the budget for many.

As you draw current from a battery pack, the voltage will very slowly decrease until the cells start to go flat and then the voltage will plummet. The time that the battery lasts for is directly related to its capacity, measured in amp-hours (Ah). A pack that can deliver 1 amp for 1 hour has a capacity of 1 Ah. Most ebike batteries are on the order of 10 amp-hours. Suppose your bike uses 15 amps on average and has a 10Ah pack, then you would expect it to last for – quick, mental calculation… – 40 minutes.

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.

My question for you is, if I just want to run a BMS for balance charge purposes only and want to wire the battery discharge directly to the motor how would I do that? Would that be a good solution as long as I monitor battery pack voltage during rides?

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. 

So after buying a 48v 20 Amp battery from Ebay (and knowing very little at that point), I realized it didn’t have a BMS and heard rumors that if i attached it direct to the controller, it would see it as a short (controller would be closed) and blow the controller.

Regarding your second question: I wouldn’t say the max amperage of the BMS is “dependent” on the controller, but it should be chosen with consideration to the controller. Think of it this way: your controller is what decides how much current your battery is going to supply. The controller is basically pulling that current from your battery. If it’s a 20A controller, that means the most it will pull out of your battery is 20A. So if you plan on riding in a style that uses full power for long periods of time (like hill climbing, dirt riding, etc) then you’ll need to make sure your BMS is rated at least 20A continuous. However, most people that ride on flat roads spend very little time at peak current. My ebike’s controller is a 22A unit, but I spend most of my time around 10-15A when cruising. A 20A continuous BMS would be good insurance in that case, because it means my BMS is rated to handle more continuous power than I generally will pull through it.

Two things to keep in mind: 1) make sure you use a thick enough wire between the series-wired modules, especially if you are going a long distance. The longer the wire, the more resistance there will be so compensate with a thick wire. 14 or 12 awg silicone wire would be great. And 2) you need to also make sure you’ve got thick enough wire for the balance wires from the BMS (since you’ll of course need to run all the small BMS wires to the modules as well). Ensure those solder joints are strong, as they’ll be on long and flexing wires with increased chance for damage or breaking at the joints. Those are normally tiny wires but if they are going to be extra long then something like 20 awg should be fine.

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.

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”.

Most electric bicycle batteries fall into the 24V to 48V range, usually in 12V increments. Some people use batteries as high as 100 volts, but we’re going to stick to a medium sized 36V battery today. Of course the same principles apply for any voltage battery, so you can just scale up the battery I show you here today and build your own 48V, 60V or even higher voltage battery.

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…

Pedals: Foldable. 26\” wheels with Aluminum Alloy spokes. Opportunity: Outdoor Camping, Mountain. 36V 8AH Lithium-Ion Battery. Material: Aluminum Alloy. Wheel diameter: Approx. Head height (To ground)…

We like to use Anderson Powerpole connectors as the standard discharge plug on all of our ebike battery packs. These connectors are ingenious since they are genderless, allowing you to use the same plug both on both a load and a source, and the connector design allows them to withstand the arc of inrush current when plugged into capacitive loads much better than bullet style plugs. For the charging port, we like to use the female 3-pin XLR plug standard. This is directly compatible with the Satiator charger, and the quality Neutrik XLR plugs are rated for a full 15 amps per pin allowing very rapid charging. Unfortunately, this option is not available for the smaller Hailong frame batteries and we are forced to use the lower current DC 5.5mm barrel plug instead.

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.

Just kidding, here’s a little more detail. 1) Yes, actually you could just use one strip of nickel on series connections to make the electrical connection, but one strip of 0.15mm thick nickel strip can only safely carry less than 10A. Ideally you want at least one strip for every 5-7A you plan to pull through the battery. 2) You can definitely do the series connections first, it is just habit for me to do parallel connections first. Also, on larger packs I like to do parallel groups first and then glue them together and do the series connections as I glue each group. 3) People have explored this idea a bit on Endless Sphere, and while it can be done, it has a lot of room for error, mostly in keeping the spring loaded contacts permanently against the cell terminals and in keeping the contacts from corroding. Spot welding is the best method, in my opinion.

Motor: 36V 350W brushless motor. · Lithium Battery— The removable 36V 10AH Ion lithium battery, equipped with smart lithium battery charger can make you ride up to 32kms. And lithium battery could a…

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…)

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!

Believe it or not, most BMS’s can handle the current from regenerative braking in the discharge mosfets as its rarely more than 5-7A. Some BMS’s (called two wire BMS’s) actually use the same mosfets for charging and discharging. Those inherently should be more than capable of dealing with the load from regen.

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?

Micah is a mechanical engineer, tinkerer and husband. He’s spent the better part of a decade working in the electric bicycle industry, and is the author of The Ultimate DIY Ebike Guide. Micah can usually be found riding his electric bicycles around Florida, Tel Aviv, and anywhere else his ebikes wind up.

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 http://electricbicycletechnologies.com 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.

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…

Thanks for the kind words! Unfortunately I don’t have access to a schematic. I got that BMS from a Chinese reseller and I would be surprised if even he has a schematic. I have seen people parallel BMS boards on a single pack to get higher current output but I haven’t tried that myself.

This is by far the most common lithium-ion chemistry used in electric bicycles. It is somewhat heavier than lithium polymer and the lithium-cobalt packs that are usually used laptops and consumer electronics, but is also safer. Most of the lithium manganese packs we have dealt with use rectangular steel canned cells and have good discharge capabilities. This chemistry holds its voltage better over the course of the battery discharge than Lithium Polymer, which tends to have a linearly declining voltage from 4.2 to 2.9 volts/cell during the course of the discharge, leading to a ebike that starts off feeling peppy and finishes feeling lethargic.

The very first consideration when choosing a battery pack is ensuring that it can handle the current draw of your motor controller. If you have a 40A motor controller, but your battery is only rated to deliver 25A max, then either the BMS circuit will shut off the battery at full throttle, or the battery will be stressed and have reduced cycle life.  The converse, having a battery that has a higher current rating than what your controller will draw, is no problem at all. In fact, it can be quite beneficial. 

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.

The nickel is surprisingly soft, which means you can use an ordinary pair of scissors to cut it. Try not to bend it too much though, as you want it to remain as flat as possible. If you do bend the corners with the scissors, you can easily bend them back down with your finger.