Battery temperature sensor. Applying the proper charge voltage is critical for achieving optimum battery performance and longevity. The ideal charge voltage required by batteries changes with battery temperature. The battery temperature sensor allows the charge controller to continuously adjust charge voltage based on measured battery temperature. Temperature compensation of charge voltage assures that the battery receives the proper charge voltage as battery temperature changes during normal operation. Without temperature compensation charge voltage would be too low at low battery temperatures leading to chronic under charging and battery damage due to sulfation. At high battery temperatures charge voltage would be too high leading to excessive water loss and undue degradation of the positive plate. Both of these conditions can impair battery performance and shorten battery life.