An apparatus is provided with a system load and a plurality of batteries that are individually selectable to provide power to the load, and arbitration circuitry configured to selectively calibrate each of the batteries in relation to respective calibration status data stored in memory for each of the batteries. The arbitration circuitry executes a method for comparing charging records of each of the plurality of batteries, and then instigating a battery power calibration procedure to a selected battery of the plurality of batteries in relation to results of the comparing step.