Help building my first 21700 battery pack

Hello, I’m currently running my first ever esk8 with a 6S 4Ah LiPo battery, which is not bad but now I’d like to upgrade to a custom pack made of 21700 cells. This will be my first time building a battery pack.

I’m going to build a 10S2P battery pack made of Molicel P42A cells.
The BMS that I’m going to use is the FlexiBMS Lite, which is charge-only.
I’ll buy one of those cheap diy spot welder from AliExpress, it should be enough for my necessities (#1, #2).

  1. What’s the best way to arrange the cells in order to make a 10S2P configuration? Is there an online tool that show how to place the single cells together? Same for the wiring of the balance connector.
  2. What’s the size of the shrink tube that I should buy to wrap the entire pack?
  3. How much nickel should I buy?
  4. I’d prefer keeping the Flexibms outside the pack for ports reachability reasons, it’s ok?
1 Like

please no
find someone local to borrow from

read through the entire battery builders thread before doing anything and that should not only answer these questions but also answer many questions you hadnt asked yet


lol, why? :sweat_smile:

I’ve seen good reviews about them…

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then youve been looking at biase reviewers
ive been down the exact same route as you and to get the battery i have currently where i can trust it to take me fast and not kill me it took a long time and buying a bad welder and etc… was the first mistake

if its just one pack you need especially if a small pack then its nearly always worth getting a builder
@Acido and @tinp123 are both super awesome builders


There’s a dedicated thread about this requests or I’ve to pm them?


pm them

used @tinp123 a bunch of times and he is super good quality and amazing builder
@acido ive only heard good things from anyone who has bought from him


Thank you man! I’ll try reaching they out.