Used for temperature monitoring to prevent overheating during use or charging.
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. Hart 20v Battery Pinout Diagram
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. Hart 20v Battery Pinout Diagram
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