Just published a new BMS design, the BMS-8s50-IC.
The main reasons for a completely new design:
- Most popular systems are based on 12V or 24V. The new BMS allows up to 8s cells (based on ISL94202) and covers these systems in one PCB instead of previously two completely different designs with either 3-5s or 6-10s chips.
- The previous designs needed two PCBs, which is more expensive to build. Now the power and control part are included into one single PCB.
- The bq76930 and -40 ICs have some issues when all cell channels are used, as the balancing and voltage measurements are not synchronized inside the chip, resulting in wrong measurement values.
- Good connection of heat sink from the bottom is now possible
The firmware support for the IC is still in progress. I’m currently also playing around with Zephyr OS instead of mbed OS. The ultra-low-power MCU STM32L452, which can be used instead of the STM32F072 in the new BMS, is not supported by mbed and I didn’t get the custom board definition to work. In Zephyr OS, everything works fine and I can talk to the ISL94202.
If you have any questions or feedback, feel free to post here or in the github issues!