A: The BMS has entered sleep or protection mode. Try placing it on the official charger for 10 seconds – this usually resets the BMS via the comm pin.
[B+ (T1)] ----[Cell 5+]
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[Cell Group]
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[B- (T5)] ----[Cell 1-] ----+
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[T3 (ID)] ------------------+ (resistor to B-)
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[T2 (Thermistor)] -----[NTC]----+
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[B-]
When looking at the top of the battery (the side that slides into the tool), you will see a series of metal contact pads or slots. While the outer plastic shroud has a specific shape to prevent reverse insertion, the electrical contacts are standardized for the Hart 20V ecosystem. Hart 20v Battery Pinout Diagram
Most Hart 20V batteries feature a 5-terminal interface. These terminals typically serve three distinct purposes: Power, Ground, and Thermal/Communication management. A: The BMS has entered sleep or protection mode
You don’t need the data lines to discharge a Hart battery carefully. You only need B+ and B-. [B+ (T1)] ----[Cell 5+] | [Cell Group] |
Simple wiring:
⚠️ Safety: Never short B+ to B-. Always use a fuse (5A-10A) and monitor cell voltage to avoid deep discharge below 15V total.
If you only need to power a light or motor and do not care about the smart features: