Battery Management System Firmware

Modular firmware based on Zephyr RTOS for low-voltage Li-ion batteries.

GitHub repository: LibreSolar/bms-firmware

Features

• Running on Zephyr RTOS
• STM32F0 and STM32L4 series MCUs (can be easily adapted to other manufacturers)
• Different cell chemistries: Li-ion NMC/NCA, Li-iron-phosphate LFP/LiFePO4
• Pack current and voltage measurement
• Monitoring of single cell voltages
• Control of balancing switches
• State of Charge (SOC) calculation using Coloumb counting and calibration based on lookup tables
• Safety features
  • Overcurrent protection
  • Short circuit protection
  • Overvoltage and undervoltage protection
  • Overtemperature and undertemperature protection
• CAN bus and serial interface with ThingSet protocol

Supported boards

• Libre Solar BMS-5S50-SC: 3-5s (12V) BMS with TI bq76920
• Libre Solar BMS-15S80-SC: 6-15s (24-48V) BMS with TI bq76930/40
• Libre Solar BMS-8S50-IC: 3-8s (12V/24V) BMS with Intersil ISL94202

Supported ICs

The firmware allows to use different BMS monitoring ICs, which usually provide single-cell voltage monitoring, balancing, current monitoring and protection features.

The chips currently supported by the firmware are listed below.

Manufacturer	Chip	# Cells	Status	Datasheet
Texas Instruments	bq76920	3s-5s	full support	link
Texas Instruments	bq76930	6s-10s	full support	link
Texas Instruments	bq76940	9s-15s	full support	link
Texas Instruments	BQ76952	3s-16s	full support	link
Renesas / Intersil	ISL94202	3s-8s	full support	link

API documentation

The documentation auto-generated by Doxygen can be found here.