Battery Management circuit for two LiPo packs in series using the common XT60 connector.
The circuit was designed with two 4S packs in mind (Input voltage: 33.6V), but will work with two 1S packs.
The output uses spring clamp connectors for solid or stranded cable up to 1.5 square millimetes (mm2).
The MCU measures voltage and current for each pack and will disable the output if either pack reaches a critically low voltage. The firmware can easily be modified to provide Over Current Protection using the Arduino IDE. The MCU will show up as an Arduino Leonardo when connecting to the USB port.
The battery level readout shows the estimated remaining capacity using 4 LEDs. The brightness level can be toggled between normal level and reduced level using switch S2 for night operation.
A buzzer will warn about low battery level (Switch S2 can disable the buzzer if desired).
Maximum electrical characteristics:
Output Current: 6A Max
Input Voltage: 6.0V Min / 36.0V Max
Current measurement accuracy: 2.5mA
Voltage measurement accuracy: 1.25mV