Many users confuse Hart with similar-looking batteries.
| Brand | B+ Terminal | Comm Protocol | Compatibility with Hart? | |--------------|-------------|---------------|--------------------------| | Hart 20V | Left outer | SMBus (custom) | N/A – only Hart tools | | Ryobi One+ | Left outer | ID resistor only | No – different thermistor mapping | | DeWalt 20V | Center outer | SMBus + ID | No – different pin order | | Black+Decker | Right outer | Simple thermistor | No – voltage mismatch |
Conclusion: Do not force a Hart battery into another brand’s tool or charger. Physical fit may be close, but electrical differences will damage the BMS or cause a fire. Hart 20v Battery Pinout Diagram
HART does not publish engineering schematics. However, these resources are helpful:
For exact voltage curves and thermistor tables, you can reverse-engineer your own battery using a multimeter and a temperature gun. Many users confuse Hart with similar-looking batteries
The HART 20V battery typically contains 5x 18650 cells in series (5S). To harvest:
Note: Many HART BMS boards have a proprietary IC that prevents voltage output if any cell is disconnected, even for a second. Proceed carefully. HART does not publish engineering schematics
A: Typically 4 or 5. Low-end (1.5Ah) – 4 pins. High-end (6Ah) – 5 pins.
If you are looking to use a Hart battery for a DIY project (e.g., powering an LED strip, a Raspberry Pi, or converting an old tool), here is how to interface with it.
If your battery requires the thermistor circuit to activate: