a battery pack of a computer system includes a battery having a nominal critical terminal voltage that may not be exceeded without hazardous failure of the battery . the battery pack includes a controller for routing power from an external power source to the battery to recharge the battery . the controller is configured to apply a time profile of charging power to the terminals of the battery . the profile includes time portions when the terminal voltage of the battery exceeds the nominal rated critical terminal voltage . the controller is also configured to control the time profile to prevent hazardous failure of the battery .