How to Contain Electrons

Hopefully, the next weeks will keep me busy building my BMS. Hey, what is a BMS. Probably everyone understands different things under that synonym. Wikipedia gives a good overview.

My BMS will be a modular one. I will have several stacks of cells distributed through the vehicle. Each stack will be controlled by a BMS handling the following tasks:

  • monitoring the cells in the stack
  • balancing the cells in the stack
  • communicating with the vehicle
  • operating the contactor

maybe, if time permits, I will also implement a health check, a charge control and a charge counter.

This week I got the most important things for the BMS, the containers for the electrons also called batteries 🙂

They were used in another project (not mine) and sitting in storage to be used again.


To be used again, they needed to be unpacked:


Each energy block was assembled into 4 cells in parallel, giving a total capacity of 400Ah.

My requirements are slightly different, so they were taken further apart


until I have 12 cells. This is the number I need for a half stack. My full stack will have 72V. My half stack already has a beefy 3.6kWh of stored energy (My ZERO S electric motorbike has 4kWh).

To be honest, I am blown away by the size of the half stack, I probably will have to reconsider my range specifications, because I might not be able to integrate 6 full stacks into my small vehicle…


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