Adding a second 76,8V 60Ah battery pack to the trunk means changes also to the circuit diagram. The low cost LiFePo4 PCM (Protection Circuit Module) that I am using is not designed for parallel connected battery packs, so I got to design how they could be used in this case.
The schematic above shows how I am going to connect the batteries. The circuit is designed so that it fills the following simple rules:
- Stop charging if overvoltage is noticed in any cell of either of the battery packs
- Stop discharging if undervoltage is noticed in any cell of either of the battery packs
Once I have installed the new batteries to Corolla's trunk, tests will show if the two rules will be filled or if more changes are needed. Once the rules are filled I am expecting many more carefree kilometers just like it has been so far.
