Patent ID: 7668624

Claim:
A method of controlling a plurality of battery voltages in a plurality of uninterruptible power supply (UPS) modules, each of the UPS modules having an inverter for providing power to a load, each of the inverters receiving power from a battery, the method comprising: determining an average voltage of the batteries from at least two of the UPS modules; comparing the battery voltage from the at least two UPS modules to the average battery voltage; and generating a control signal responsive to the comparison that causes the inverters to adjust the amount of power delivered by the batteries to the load, the control signal intentionally causing an imbalance by intentionally increasing the amount of power delivered from at least one of the batteries who's voltage is greater than the average battery voltage and intentionally decreasing the amount of power delivered from at least one of the batteries who's voltage is less than the average battery voltage, wherein intentionally causing an imbalance comprises intentionally placing one or more of the inverters in an overload condition.