The Battery Temperature Sensor (BTS) from Schneider Electric is equipped for use with C Series Charge Controllers (also for replacement on Xantrex SW and DR inverters). The BTS is a temperature sensor that attaches to the terminal post of a battery in a bank or to the side of a battery. It sends precise data to the charger or charge controller, which changes voltage automatically based on the ambient temperature of your battery installation to ensure maximum battery charge. To secure your batteries and provide optimum charging for each bank, Schneider recommends installing Battery Temperature Sensors on all banks. Comes with a 35 foot cable.