Self heating heater

Abstract

The invention relates to a power management system for supplying backup DC power to peak and/or high current demand battery applications, such as motor starting or an uninterruptible power supply (UPS) used to power a critical load, such as, a data bus or other critical load, after an event, such as loss of primary AC or DC input, during relatively cold ambient temperatures. Two or more heaters can be provided; for example, a low power heater and a high-power heater. In a maintenance mode, the low power heater is used to maintain batteries at a predetermined temperature. In this mode, a battery charger is used to power the low power heater. In a boost mode, after the primary AC or DC input is restored, and battery temperature is too low to back up the critical load, the battery charger supplies power to one or both of the heaters. Since capacity of the battery charger is normally insufficient to heat the batteries to an acceptable operating temperature in a relatively short period of time, a portion of residual power from the batteries is used to boost power to the heaters in order to speed up the time to get each battery of said batteries to its rated operating temperature.