Patent ID: 8175825

Claim:
A method for operating a portable information handling system to calibrate and determine power usage information, comprising: providing a portable information handling system including a battery, a charger, and an AC/DC adapter; powering down the portable information handling system; charging the battery using the AC/DC adapter; while powered down calibrating an input power measurement for the portable information handling system by measuring battery charge with the battery; measuring input power with the charger; and comparing the input power measurement to the battery charge measurement to determine a calibration factor for the input power measurement; powering on the portable information handling system; operating the portable information handling system using power provided through the AC/DC adapter; and determining power usage for the portable information handling system by measuring input power with the charger; adjusting the input power measurement by the calibration factor to generate calibrated power usage information; and utilizing the calibrated power usage information as an indication of power usage for the portable information handling system.