Patent ID: 7880438
Filing Date: 2011-02-01
Classification: G01R,H02J

Abstract:
1. An uninterruptible power supply system comprising: an input configured to couple to a power source; an output configured to couple to a system load; a battery; power circuitry coupled to the input, the output, and the battery, and configured to transfer power from the input to the output and to transfer power from the battery to the output; a test load; a test switch coupled to the battery and the test load and configured to selectively couple the battery to the test load; a voltage monitor coupled to the battery and configured to provide an indication of a voltage provided by the battery; and a processor coupled to the test switch and the voltage monitor and configured to effect a first partial-discharge test on the battery by actuating the test switch to couple the battery to the test load to partially discharge the battery, and by using information from the voltage monitor regarding the voltage provided by the battery at different times during the test before a complete discharge of the battery to determine a capacity of the battery, wherein the processor is configured to use first and second indications from the voltage monitor of the voltage provided by the battery at first and second times, and to use a voltage decrease between the first and second times to extrapolate a future voltage decrease of the battery to determine a predicted runtime of the battery to reach a virtual cutoff voltage associated with an actual cutoff voltage associated with the battery.