Patent ID: 8648568

Claim:
A backup power system configured to be coupled to a power source, comprising: a plurality of batteries each comprising one or more cells and used to provide power if a power source fails; and processing logic coupled to the plurality of batteries, configured to monitor a state of each of the plurality of batteries, and further configured to control a charging and discharging of each of the plurality of batteries; wherein, if the power source has not failed, the processing logic repeatedly and sequentially causes each of the plurality of batteries to discharge while at least one of the remaining batteries remains fully charged, and further monitors a power provided by each of the plurality of batteries while discharging; wherein the processing logic determines an available energy stored in each discharging battery when fully charged based upon a power provided by the discharging battery during a time it takes for the discharging battery to discharge; and wherein the processing logic causes a battery of the plurality of batteries not to be used to provide backup power based on the battery's available energy being determined to be below a minimum operating threshold value.