Tripp Lite APS inverter/chargers are the most reliable source for AC power, regardless of operating conditions. They have three main components: 1) an inverter, 2) a battery charger, and 3) power conditioning components such as a surge/noise filter and frequency-control circuits. When AC power is present, the inverter/charger automatically passes conditioned power through to connected equipment: blocking potentially damaging power surges, filtering disruptive line noise (which can help improve audio/video performance) and regulating frequency (which can help equipment perform at their peak). While passing through conditioned power, Tripp Lite inverter/chargers also simultaneously charge a connected battery bank, preparing it for use when power is absent. When power is absent, the inverter/charger converts DC power from the connected battery bank into AC power to support connected equipment - automatically and without interruption. Battery runtime is determined by the total amp-hours and condition of the user-supplied batteries.