⛔ NEVER BYPASS THE BMS
Do NOT connect robot power directly to the raw cell terminals (0V and 8.4V). Always use BMS OUT+ and OUT−. The BMS provides over-discharge protection, short circuit protection, and over-current cutoff. Bypassing it risks fire, cell damage, and equipment destruction.
⚠ COMMON PORT — CHARGER CONNECTS TO OUT PADS
This is a common-port BMS. Both the charger and robot connect to the same OUT+ / OUT− pads. Do NOT wire the charger directly to the cell terminals. The BMS internally manages the charge/discharge path switching.
⚠ CELL POLARITY IS CRITICAL
Reversing any cell will cause immediate BMS shutdown or permanent damage. Double-check with a multimeter before inserting cells. Cell 1 − goes to 0V, the series junction (Cell 1+ = Cell 2−) goes to 4.2V, Cell 2+ goes to 8.4V.
ℹ BMS SLEEP MODE — NO OUTPUT ON FRESH WIRING
Many BMS boards enter a protection/sleep state when first wired or after over-discharge. If OUT+ → OUT− reads 0V, connect the USB-C charger briefly. This wakes the BMS and restores the output. Normal behaviour — not a fault.
ℹ SWITCH PLACEMENT — ON THE POSITIVE LINE ONLY
Always place the power switch between BMS OUT+ and Robot+. Never switch the negative line. Switching GND can cause floating ground issues with the ESP32 and other modules.
✅ BALANCE CHARGING — USE THE 4.2V TAP
The 4.2V mid-tap pad enables the BMS to balance both cells during charging. Always connect this wire. Without it, the board charges both cells as a single pack with no per-cell control — cells will drift apart over time and reduce pack life.
✅ RECOMMENDED: ADD A LOW-BATTERY LED OR BUZZER
Wire a voltage divider from OUT+ to ESP32 ADC pin to monitor pack voltage in firmware. Alert at ~6.8V (3.4V/cell) and cut motors at ~6.0V (3.0V/cell) before the BMS does it hard. Protects cells and gives graceful shutdown.