| Pin Number | Label | Function | |------------|--------------|------------------------------------------------------------| | 1 (Left) | | Battery Positive (+), 20V Max (21V hot off charge) | | 2 | CH or ID | Charge enable / Thermistor or ID resistor (depends on model) | | 3 | C or S | Communication (SMBus Data line) – talks to charger & tool | | 4 | B- Sense | Negative sense / Cell tap (sometimes unused) | | 5 (Right) | B- | Battery Negative (-), ground |
These additional internal contact points allow the charger to monitor the voltage of individual cells (typically around 4V increments: 4V, 8V, 12V, and 16V), ensuring they are evenly charged. Positive (+) and Negative (-): These provide the primary 20V power output for your tools. Safety & Diagnostic Features Under-Voltage Detection: Hart 20v Battery Pinout Diagram
The "boost" was just enough to wake up the internal sensors. Max snapped the battery back into the Hart charger | Pin Number | Label | Function |
Hart 20V batteries utilize a proprietary block-style form factor. Unlike the slide-on rails of Dewalt or the stem-style of Black+Decker, Hart batteries usually feature a top-mounted interface with exposed contact pads. Max snapped the battery back into the Hart
The is more than a technical drawing—it’s your key to extending battery life, building custom adapters, and diagnosing failures without guesswork.
: The main ground/negative terminal, usually located on the far left. Internal Balancing Contacts (C1–C4)
The is more than just a wiring guide – it’s a gateway to understanding how smart batteries communicate with tools and chargers. By identifying B+, B-, the temperature pins (T1, T2), and the critical ID pin, you can troubleshoot dead packs, harvest cells for solar projects, or safely build adapters.