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Battery Build Planning

oVxrtex

New here
Joined
Jan 12, 2025
Messages
22
Location
Suburbs of Chicago
Hello guys, I previously got some help with how the systems of an e-bike (battery, motor, controller) work together, so now I’d like to try planning a battery with you guys :).

Some minimum requirements:
- Not too heavy (100 lbs or more is outrageous to strap on a bicycle).
- Decent energy/power density (Preferably a balance, because I’d like the power but I also want to be able to ride the whole day, explained later in the post).
- Be able to ride the whole day, stopping and starting, at around 20-30 mph (whole day = 6 hours as an estimate, let’s say 20-30 mph is 750 watts, depending on the weight of the bike, and disregarding hills because my area is pretty flat, so pretty much a ~4-5kWh requirement, I might change this later though).
- Good power (I don’t have a top speed requirement, but I want to be able to keep up with traffic in my area, so about 50-60mph if possible, but if not that’s fine just make sure its close)
- Be able to pedal (4 in thinnest measurement in battery, maximum)
- Have a good mounting solution (I’ll post a geometry sheet whenever I find one).

Some background info:
- $1200 budget **for the entire build** (probably $800 MAX for the battery), technically $1400 but I want to save money for shipping in case some parts come from china/etc.
- Bike is a Schwinn Al Comp, 27.5 in mtb tires, don’t know anything past this but I’ll post a geometry sheet once I find one (unless someone can find one for me) :)
- Don’t ask why I can’t get a motorcycle or dirtbike, because I live in an apartment with limited parking spaces and I also need it to be quiet so I don’t annoy anyone by me
- I can’t use another bike as of right now, but if you tell me about a cheap steel frame bike that is sturdy and has a large frame, I might be able to buy it sometime soon (but otherwise don’t tell me it’s unsafe, I know but I don’t have many other options) :)
- I’m doing this for fun, so if I can’t go 60 or get 4kwh in a reasonable manner with my budget, it’s fine. Just tell me about the best stuff you’ve found so far.
- PREBUILT BATTERIES ARE FINE!! I want to make my own, but I doubt that there’s a way I can do that with the materials I have on hand. If you can find modules that I’m able to hook together without welding, that works, and cells I can look into and maybe do, but if you find prebuild batteries that are a really good deal, share them here.


Thanks for reading this and contributing to my build with your ideas if you do so :)


Edit: I forgot to put this in here, but here’s my options so far:

1. $600 (+ $200 shipping) Prebuilt Amorge battery, 72v40ah, 250A nominal 350A peak (highly trusted company, it’s not a scam trust me)
Pros: Prebuilt, *should* fit, almost guarenteed to work, lightweight (still able to pedal relatively easily).
Cons: expensive ($800 total), low capacity for the price (I know it’s actually really good, I just don’t have much money and I want the best deal possible), will take a while to get here (but that’s probably the same with everything else on this list too).

2. $400 (+ shipping and other battery building stuff) 20s10p “LISHEN” batteries, 72v40ah, 350A cont. 450A peak
Pros: great price, power
Cons: Have to build it, cheap chinese cells aren’t super reliable, kWh isn’t amazing (2.9 kWh), have to pay for battery building materials + bms

3. $200 (+ shipping and bus bars and bms) 2s5p Battery Hookup battery module (no name, but uses panasonic cells), 83.6v32ah, 3078.4 Wh, 500A cont. discharge, 25A charging as well
Pros: Amazing power & capacity for the price, reliable cells
Cons: Have to get a bms and bus bars, mounting is gonna be tough, and kWh isn’t what I’m looking for, though I could increase the amount of cells in parallel (7 instead maybe) they would be very hard to mount, as they’re already taking up 13*6*2.25 in of space with one, 10 is already pretty difficult to mount, and 14 is gonna be really difficult but maybe possible, also the voltage is pretty high and finding a motor/controller for it is gonna be more expensive & difficult than a 72v
 
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Been months.. what did u do?



Id get these and save a lot. As long as u do two or three in parallel they have enough power.. for my wants at leasr



U could buy a huge 3d printer and cheap welder with the money u save.


I think no bms needed and externally balance with lifepo4 is acceptable
 
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