The battery builders club

I’m thinking some funny things like 12s6p 21700 (40T or p42a) in a prototipo with an enclosure spacer, custom 3d printing some kinds of battery holders to help.

would end up with 10-15mm of spacer needed to include padding and wiring room.

here’s some rudimentary mock up:


i’ve been waffling between do something unique and interesting… or do something more standard. (12s5p no stagger ) originally wanted 150% more wh from stock. 10s5p 20700b. but I have another commuter board now so I could let this idea go. so I keep waffling on how hard I want to challenge myself.

looking for opinions.

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Honestly I don’t think that staggering is the move, if you are really hurting for range get a top mount pack. Also P42A all the way

I mean it will work but you loose out on padding and easy wire management, plus making it will be a bit of a pain when it doesn’t have to be

I suppose you can also try QB8600 cells? They might fit

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Working on a project I thought up.
I wanted a way to travel on an airplane with my board.
I also wanted a 12s4p from molicel p42a.
I came up with this…
4p glued together using 21700 nese hardware.
Direct solder balance wires and series connections to tabs. Use 10awg to connect series allowing flexibility between P groups.
Planning on using black RTV to secure the nese hardware to the enclosure.
I am planning on using a friction fit for the cells to stay in place. Then closed cell foam on top of cells to take up the rest of the space in the enclosure so they have no where to go… roast away…

thoughts: nese bolts together to provide connection pressure? this friction fit could be too loose?

@fessyfoo I’m clamping wooden template blocks to the nese tabs that are a little bit shorter than the cells. Using the RTV silicone it’ll have a little bit of give. I should be able to find a good distance/pressure to keep the cells seated. There’s not much room for them to go anywhere but up, and that’ll be covered in foam and bolted down…

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where do people get theirs? they seem to make for quite the expensive pack. and they’re slightly larger I hear. closer to 22 than 21 diameter. also 40Ts. or P42A at 5 or 6P could botth do 120A which is as much as the unity i’m gonna use could handle.

Also @PixelatedPolyeurthan game me this trusted opinion:

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Wondering if anyone knows how I should charge this battery, says it’s a liion, but only has a possitive and negative terminal. Would a 12volt trickle charger work?



It’s an Lg Chem battery I got from battery hookup. I think it is used in some evs

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Follow this dude for battery porn

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Maybe someone can help:
I’ve got a hb83 and built an 8s4p 30q pack.


I used this bms with an e-switch function but i can’t get it to work. The Android app lets me turn the battery on and off remotely but the switch can’t do this. (It seems i need a pc programming adapter to activate this feature which i don’t have.)
This is the switch I used. Nothing special, just on or off

Now the question:
Does anyone know how to turn the switch function of the bms on without the programming adapter or if this doens’t work maybe someone could sell or lend me such a programming thing.

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some anti-spark switches require momentary switches, yours is latching… which does your BMS require?

and no I ain’t gunna read your BMS specs

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BMSs usually don’t use a momentary switch. The switch isn’t the problem here.

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Yes I think it’s absolutely too loose

Any reason to get 4s over 3s for a kWeld? Or would the money be better spent getting more capacity?

  • 4s 6000mAh
  • 3s 8000mAh

0 voters

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I don’t know about the kweld, but my Malectrics steps down the 12v from my car battery to like 3.3v~4.7v while still pushing a lot of amps. So I dont think a higher voltage would be very beneficial.

i cant remmember for sure, but doesnt kwweld take 2s?

It links a 3s graphene lipo and a 12v PSU, but I think the voltage it accepts would work with 4s

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Ahh gotcha. I wouldnt worry about getting higher voltage stuff, deffienlty go for capacity in my opinion

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3S is the recommended for ~12V operation. Dont think 2S is going to work, but I think I remember someone in the Facebook page saying they used 4S, not sure tho.

4s will spark too much, read up on he kweld thread on endlessphere

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The user manual says up to 30V so in theory you can run a fully charged 7s, but I honestly don’t understand spot welders at all so I have no idea what anything means