First battery build - advice needed on bus bar

Hello guys,

I’m building my first battery pack. It’s a 12s9p 36Ah with Molicel P42A 21700 cells.

I have doubled my series connection as you can see on the picture below.

Im planning to use these bus bars with 8 awg wire. is it the good way to do it ? Could the nickel become hot as it’s not doubled here or because it’s linked to the wires it will handle it ?

I don’t want to do anything bad as i spent a lot for this pack :smile:
I don’t wan’t to burn during a ride neither :sweat_smile:
I need your experience.

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Hi, I`m not shure the amp rating of the ladder style nickel strip, it is all about the weakest link. I used 25mmx15mm on two 10s 5p batteries the same 8awg and next time would use two 8 awg. There is a ton of reading on the

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What thickness is your nickel strip? The ladder at each end will be the weakest part if it’s single layer, each cell has to go through a single narrow ladder to get to the thick 8awg wire.

I have 30mm wide x 0.2mm nickel (solid strip, not laddered) for my 13s6p molicel p42a build, and I’m hoping it’s sufficient for up to 100A from 6p.

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Thanks for the link, I will make some research and come back with what I will I find

It’s a 0.2mm. I’ve read that for the start, motor consume about 150A for seconds to get out of the water before stabilizing near 30A. (it depends of the weight of the guy and the system). But if I get 150A with 9P, it means that 16.66 Amps will go through each ends strip. I don’t know if this nickel strip can handle it, even during a short time

This is a good design, you should not have any problems.
I have a 14x8P p42 pack and only use 4x 0,3mm strip ladders to connect to cables.
Have run it up to 130A, no problems yet.
Have about 2v drop when loading 100A during start. You will probably have less.

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Good design to me as well
Bus bar are really important , the nickel plate between two cell and bus bar , not that much , .15 can do most of the job : because it is over a short length

All numbers given around the net do not inclue the length …

Nickel plate between two cells can probably hold 800-1000A ( test on YouTube) before it melts

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Thanks guys for all the answers.

I’m a bit more ensured right now :sweat_smile:. All your answer goes to the same direction.

Here another answer I get from the esk8 forum if it can help anybody else for building is own pack :


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Yes on paper but that one thing I will not do : solder my cells , way to much heat for the cell in order I have a good solder with 12-16 awg wires

The insolator white plastic ring on top , is really fine

Hey @Alexandre, i thought I could solder small wires to the nickel strips then spot welder the entire thing to the cells in order to avoid heat which you have mentioned. Something like this :

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Yes it is the correct way to add this ( even if I think it is not necessary) , just do it if you feel less worried :wink:

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