Power distribution in a portable device

A power distribution system is provided for distributing power in a portable device being coupable to a charging system and including a main battery power and a bridge battery power. The charging system is coupled to a power bus through a diode. The main battery power system and the bridge battery system are also both coupled to the power bus through diodes. The predetermined voltage level is set with respect to the charging system, the main battery and the bridge battery, such that if all three are coupled to the bus, the recharging system both powers the unit and recharges the main battery. If the recharging system is removed, the main battery power system powers the portable device, and if the main battery power system is removed the bridge battery will provide power to the portable device. The distribution system also includes a monitoring system for measuring the predetermined charge level on the battery and disabling a FET switch, so that the main battery stops charging to protect the main battery against overcharging. A monitoring system is also provided for monitoring the voltage level of the main battery utilizing a comparator system.