Beyond the five external pins, Hart batteries contain internal contact points (C1, C2, C3, and C4) accessible only during teardowns. These are used for , ensuring each of the five individual lithium cells stays at roughly the same voltage (e.g., 4V, 8V, 12V, and 16V relative to the negative terminal). DIY Tips and Safety
For those troubleshooting or building Battery Adapters , standard voltage readings between pins (at full charge) are as follows: Pin Connection Voltage Reading ~20V (18V nominal) Main power supply (+) to TH High-side temperature monitor (-) to TH Ground reference for thermal sensing (-) to ID Ground reference for ID resistor (-) to C Control signal path Internal Balanced Charging Pins
Many Hart tools have a "fat" positive pin designed to detect low voltage. If you are using an adapter for a non-Hart tool, you may need to bridge certain pins to prevent the battery from cutting out prematurely. Hart 20v Battery Pinout Diagram
The ground or common return path for the circuit. Voltage Measurements & Technical Specs
Allows the tool or charger to identify the battery type and capacity. Beyond the five external pins, Hart batteries contain
The standard Hart 20V battery interface consists of five primary terminals. When looking at the battery with the connectors facing you, the layout generally follows this identification: The main power output terminal.
If your battery flashes specific patterns on its Built-in Fuel Gauge , it may indicate a temperature out-of-range error or a permanent cell failure. If you are using an adapter for a
A communication or control pin often used for low-voltage protection or signaling.
Understanding the is essential for DIY projects, such as creating custom battery adapters or repurposing batteries for Power Wheels. These lithium-ion packs typically feature a 5-pin configuration that handles power delivery, safety monitoring, and balanced charging. Hart 20V Battery Pinout Configuration