The only thing left to do at this point is to add the connectors, unless you did that before you soldered the wires on, which I actually recommend doing. But of course I didn’t do that, so I added them at this step, being careful not to short them by connecting only one wire at a time.
Thank you for the article! I am currently making a battery for an electronic skateboard, so I need the layout to be as thin as possible to allow ample room underneath the deck. Currently, I have 6 packs of 3 cells welded in parallel, and would eventually like to create a battery which is 9 cells long, 1 wide, and 2 high, for 18 in total (the two packs of nine would then be welded in series). I am wondering if I could be able to make 2 battery packs by welding 3 of my current 3 cell packs together in parallel to make a long, yet skinny pack, and then welding both packs of nine in series using the alternating system. Essentially, I would be creating a pack that would look like 3 of the ones you show above when making your first series connection. Let me know what you think, and thank you!
36V 10ah Lithium battery (Included with the battery is the charger and mounting Bracket). Standard 26 in Front Wheel 500w brushless motor hub (works with V-brake or disc brakes). Pedal Assistance syst…
I have come to the conclusion that a 48v battery would probabky be sufficent for my needs. I need to ride continuously for at least 7-8 hours–but prefer up to 10 hours– at 15-20mph everyday. Although I also need a top speed of 30mph, at times. If my math is right, in order to accomplish this I need to build at least a 14s8p battery. After running these specs through a simulator I found that the power starts to drop at about 1150 watts and 20mph.
I am currently building my own 36v battery and now using some of the ideas you have put here. but I am wondering what is going to be the best charger for charging the battery?? As I am doing on the cheap, I am utilising a 12v 6A charger which I previously had. My plan was to couple with a 12v to 36v step up DC transformer but then realised that this may not be enough to charge the battery fully. This is because the full charge voltage on the battery is actually 41v which would be higher than the step up transformer. The next option is a 48v charger which would be too high.. Or would the BMS kick in and protect from over voltage?? This is all theory at the moment so I am probably missing something.. Could you suggest a charger method. Am I on the right track?
2018 model Pedalease Estar MTB electric mountain bike 1000w or 1500w rear hub motor with option of 48v 10ah, 48v 11.6ah and 48v 17ah lithium battery. Motor: Pedalease 1000W or 1500w rear drive brushle…
You will find here all Li-Ion/LiFePO4 EBike battery packs and cells, battery management system(BMS). This category includes 12V~72V Li-Ion/LiFePO4 EBike battery packs and cells, EBike bottle battery, high power battery and high C-Rate cells, 4~24 cells in series Li-Ion/LiFePO4 bleeding balancing BMS and 5~13s smart BMS.
You’ll see two dots where http://electricbikecharger.com weld was performed. Test the weld by pulling on the nickel strip (if it’s your first time using the welder). If it doesn’t come off with hand pressure, or requires a lot of strength, then it’s a good weld. If you can easily peel it off, turn the current up. If the surface looks burnt or is overly hot to the touch, turn the current down. It helps to have a spare cell or two for dialing in the power of your machine.
The Panasonic NCR18650B cells you have are very good quality cells. I used similar cells also made by Panasonic, but mine are the NCR18650PF (not B). The difference is that yours have more capacity (mine are 2900mAh, yours 3400mAh) but yours have a lower constant current draw rating. I don’t remember what it is off the top of my head, but I don’t think it’s much more than 5A per cell. So just make sure that you either use enough cells in parallel and/or limit your controller to not draw more power than the cells can handle. Check the cell specification sheet which you can find on Google somewhere to ensure that you are staying within the cells’ limit.
Battery packs are made up of individual cells connected together. Each cell has a more or less constant voltage dependent on its chemistry. For NiCad/NiMH, this is about 1.2V, for lead acid it is 2.0V, and for lithium cells it is on the order of 3.7V. Typical ebikes and scooters are designed to run on 24, 36, or 48 Volts, so a number of cells have to be series connected into a ‘battery’ that has the desired net voltage. A nominal 36V pack could be made from 10 lithium cells, 18 lead acid cells, or 30 NiMH cells.
When comparing between battery chemistries, one of the most relevant metrics is the Energy Density in watt-hrs / kg. This figure says how heavy a battery pack will have to be to achieve a certain range. For Lead Acid it is 20-30 whrs/kg, for NiCad it is 35-40 whrs/kg, NiMH is 50-60 whrs/kg, Li-ion is ~110 whrs/kg, and Li-Polymer is up to 160 whrs / kg. Knowing these values makes it easy to project the weight of a pack without having to look up data from the manufacturer.
The BMS I chose is a 30A maximum constant discharge BMS, which is more than I’ll need. It’s good to be conservative and over-spec your BMS if possible, so you aren’t running it near its limit. My BMS also has a balance feature that keeps all of my cells balanced on every charge. Not all BMS’s do this, though most do. Be wary of extremely cheap BMS’s because that’s when you’re likely to encounter a non-balancing BMS.
A big downside of lithium batteries is that they are much more expensive than lead acid batteries. Prices vary depending on the voltage and capacity of the lithium battery, but standard ebikes usually have lithium batteries starting in the $300 range and rising quickly from there. Most bikes I build have lithium batteries in the $400-$500 range.
There are many different types of lithium ebike batteries to choose from. I’ll give a short summary of the different types of electric bicycle specific lithium batteries here, but you can get a more detailed description as well as the pros and cons of each type of lithium battery in my article Not All Lithium Batteries Were Created Equal.