Understanding the pinout is not just about matching red to positive and black to negative. Modern lithium-ion batteries use a communication protocol between the battery management system (BMS) and the charger. Get it wrong, and you risk bricking a good battery or creating a fire hazard.
Most HART 20V battery packs (models like HGB20, HGB40, HGB60, HGB80) have on the top mounting rail. The common mistake is assuming only the large outer slots (positive and negative) matter. In reality, the inner smaller pins are the brains of the operation. The Official HART 20V Battery Pinout Diagram Below is the standard terminal layout as viewed from the battery’s top mounting face (the side that slides into the tool). Terminal Identification (Left to Right) | Terminal Label | Shape/Size | Primary Function | Typical Voltage | |----------------|------------------|--------------------------------------|------------------| | B- (Neg) | Large flat slot | Main negative / Ground | 0V (Reference) | | T2 | Small square pin | Temperature Sensor (Thermistor 2) | ~0.8V - 2.5V | | T1 | Small square pin | Temperature Sensor (Thermistor 1) | ~0.8V - 2.5V | | ID | Small square pin | Battery Identification / Data (1-Wire) | 0V - 5V (PWM) | | B+ (Pos) | Large flat slot | Main positive (Pack voltage) | 20V (Nominal) | Hart 20v Battery Pinout Diagram
If you own HART power tools (sold exclusively at Walmart), you know they offer excellent value for money. But what happens when a battery dies, won’t charge, or you want to salvage those high-drain 18650 cells for another project? You need the HART 20V battery pinout diagram . Understanding the pinout is not just about matching
Note: Some lower-capacity HART 20V batteries (2.5Ah) may lack the second temperature pin (T2) and have only 4 terminals: B-, T1, ID, B+. Imagine looking at the battery’s connector slot. The terminals run along the top edge: Most HART 20V battery packs (models like HGB20,
| Brand | Terminals | ID Method | Cross-Compatible? | |-------|-----------|-----------|-------------------| | | 5 (B-, T2, T1, ID, B+) | 1-Wire serial (TTI proprietary) | No (with Ryobi/Milwaukee) | | Ryobi 18V | 6 (B-, T1, T2, ID, B+, HS) | Analog resistor (different Ω per Ah) | No – Physical slot different | | Milwaukee M18 | 7 (B-, T, C, B+, 3 balance) | Digital handshake + temperature | No | | DeWalt 20V | 4 (B-, C, TH, B+) | Single-wire proprietary (TD) | No |