A method and apparatus for adjusting the charge for a battery under a power sharing arrangement is disclosed. In one embodiment, the method comprises determining if power output capacity of an alternating current (AC) adapter is less than or greater than a system power requirement for a system that receives power from the AC adapter and a battery, determining a charge current for charging the battery from the AC adapter, based on a voltage range of the battery, the current charge being less than excess current available from the AC adapter in view of determining that the power output capacity of the AC adapter is greater than the system power requirement, and controlling a battery charger to charge the battery with the charge current by specifying the charge current to the battery charger if the power output capacity of the AC adapter is greater than the system power requirement.