Abstract: A portable electronic device determines a battery available power for the device's battery and manages device power usage based upon the battery available power. The device includes a battery and a controller. The controller is configured to receive a first voltage value for the battery at a first time, a first current value for the battery, a second voltage value for the battery at a second time, and a second current value for the battery. It is determined that a time difference between the first time and the second time exceeds a predetermined time threshold. An estimated resistance of the battery is determined based at least on a first difference between the first current value and the second current value and a second difference between the first voltage value and the second voltage value. Real-time power usage of the device is controlled based on the estimated resistance of the battery.

Abstract: A system and method for operating a portable electronic device are presented. The device includes a battery and a controller. The controller is configured to execute instructions for determining a first resistance value for the battery during a first power cycle of the battery, and determining a second resistance value for the battery during a second power cycle of the battery. The second power cycle is after the first power cycle. The controller is configured to execute instructions for determining that a first difference equal to the first resistance value subtracted from the second resistance value is less than a first predetermined threshold value, and electrically isolating the battery. In an embodiment, the first resistance value and the second resistance values are determined at the same state of charge for the battery.