In this tutorial, I am going to show you how to build a 12S2P electric skateboard battery pack. I am using 21700 Samsung 40T batteries(which I highly recommend for more power with compact size) but you can use any size battery, the only real difference is just size of the battery cells and the final batter pack.
In Part 1, I show you how to hot glue the batteries together and also spot weld it. In Part 2, I will show you how to solder BMS(Battery Management System) to the built battery pack so you can safely re-charge the battery pack.
WARNING, building battery packs are not laughing matter, make sure to wear rubber gloves at all times and also use kapton tape to temporarily tape any open terminals as you do NOT want to short any of the terminals which can easily cause fires or even KILL YOU. Make sure to tape off the first battery negative and last battery positive as they are the end terminal points of the battery pack and carry the full 50 volt load.
I recommend 12S2P if using VESC as you get a ton more power for less current, also much less voltage sag meaning you can go at full power much longer than 10S2P.
This particular battery pack specs:
344wH capacity
70 amps continous discharge
90 amps continuous discharge under 80 degrees celcius
fully charged 50.4 volts
4000 watts of continous power
If you bypass the BMS, you don’t need to use a high current BMS since BMS is only used for charging and keep the overall battery pack smaller and also spend less on BMS. Since you only need a few amps to charge your battery pack, you can just grab a smaller BMS.
For discharge, you can use VESC to control the maximum battery current which will keep everything safe and take over BMS’s job. You will however need to use an anti-spark switch. Flipsky 4.20 Plus or 6.60 Plus comes with built-in anti-spark. You can also attach an anti-spark switch between the battery and VESC or make a loop key too.
For my setup I am using Flipsky 6.60 Plus so I can just directly connect the battery pack since it has built in switch. In my experience it works quite fine as one time it saved my battery pack.
Make sure to double check all your wiring with multimeter before connecting the BMS wires! I skipped that step but you should check it if it’s your first time building a battery pack.
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