Described is a system and method for charging a battery. The system includes a processor powered by a battery; and a controller determining a remaining battery charge of the battery. The controller sets a first charge current to recharge the battery when the remaining battery charge is insufficient to operate the processor. The controller wakes the processor when the battery has been recharged so that the remaining battery capacity is sufficient to operate the processor. The processor negotiates for a second charge current to recharge the battery. The controller sets the second charge current when the processor successfully negotiated.