A battery pack includes a switching control port, a battery stack, an output power port, and switch circuitry. The switching control port receives a switch control signal from a battery pack port. The switch circuitry selectively couples the battery stack to the output power port based at least in part...http://www.google.com.au/patents/US20050142434?utm_source=gb-gplus-sharePatent US20050142434 - Battery pack with internal charge/power switching
