Xantrex 808-0232-01 Battery Temperature Sensor for Use with TRUECharge2 Chargers TRUECharge2 Battery Temperature Sensor (BTS) Designed for use with TRUECharge2 battery chargers. The BTS mounts on a terminal post of a battery in a bank or on the side of a battery and measures its temperature. Sends precise information to the charger or charge controller