BATTERY BACKUP CAPACITY DETECTION

A method, system, and integrated circuit are provided for monitoring a battery capacity within a battery backup system. A battery degradation profile is provided for a battery including first data associating operating temperature over accumulated time with second battery degradation data. The battery is kept charged in a failover battery backup circuit. The operating temperature of the battery is measured over time and third data is stored for the operating temperature over accumulated time. While the battery is operated in the backup system, the battery degradation profile is accessed based on the third data to obtain an associated battery degradation estimate. Responsive to the battery degradation estimate meeting a designated condition, the battery is electronically switched from operation to a test circuit, and the internal impedance of the battery is measured. Responsive to an unacceptable value of the internal impedance, an alert is issued.