E-Scooter BMS
The why
After moving closer to work, only a 1.6 mile, 5 minute drive and 2.3 mile walk, I decided to get a used Razor E300 scooter and replace the BMS, originally with 2 lead-acid battery packs in series for 24V with a lithium-ion 18650 pack using BAK N18650CNP 18650 30A Flat Top 2500mAh and a TI battery gauge (obviously) with INA238 for data collection.
The design
The brains will be the nRF52840 Seeed Studio XIAO, mostly because I did not want to spend a lot of time developing the code and this module has Circuitpython support with BLE and I2C.
Critical BOM:
• nRF52840 Seeed Studio XIAO - MCU
• BQ40Z80 - battery gas gauge
• INA238 - high sample rate ADC
• TLV76015 LDO - powering the INA and MCU
• 2 push buttons for MCU control
• 1 push button for SOC LED display function of BQ40Z80
• Micro SD slot for data logging
• 2 parallel back-to-back protection FETs
• 6S4P BAK N18650CNP 18650 30A Flat Top 2500mAh
Critical BOM:
• nRF52840 Seeed Studio XIAO - MCU
• BQ40Z80 - battery gas gauge
• INA238 - high sample rate ADC
• TLV76015 LDO - powering the INA and MCU
• 2 push buttons for MCU control
• 1 push button for SOC LED display function of BQ40Z80
• Micro SD slot for data logging
• 2 parallel back-to-back protection FETs
• 6S4P BAK N18650CNP 18650 30A Flat Top 2500mAh
E-scooter BMS schematic - EasyEDA
E-Scooter BMS PCB top layer - EasyEDA
E-Scooter BMS PCB bottom layer - EasyEDA
E-Scooter BMS 3D PCB View - EasyEDA
The results
After some tuning of the protection settings of the BQ40z80, everything seems to work well!
Completed E-Scooter battery
Installed battery pack
Conclusion
Conclusion will be soon to come after testing.
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