Patent ID: 8125194

Claim:
A method of charging a plurality of electrical devices by coupling them to a power source selectively through interruptible current limiting and low impedance electrical circuit paths, each electrical device including a battery coupled to a power supply, the current limiting circuit path including a series-connected first switch and current limiter, and the low impedance circuit path including a second switch, and the current limiter characterized by a state of thermally sensitive high impedance that decreases to a state of lower impedance with an increase in temperature of the current limiter, the method comprising: providing a first control signal to which the first switch responds by selectively allowing and interrupting current flow through the current limiting circuit path; and providing a second control signal to which the second switch responds by selectively allowing and interrupting current flow through the low impedance circuit path, the first and second control signals provided in cooperative first and second switching states to the first and second switches, the first and second switching states operating during respective first and second time periods that at most partly overlap each other and have preselected durations, and the first time period starting before and being shorter in duration than the second time period, the first and second control signals in the first cooperative switching state causing, during the first time period, current flow through the current limiting circuit path and thereby through the current limiter in the high impedance state to couple the power source and the plurality of electrical devices and to prevent a transient inrush of current to the plurality of electrical devices, and the first and second control signals in the second cooperative switching state causing, during the second time period, current flow through the low impedance circuit path to couple the power source and the plurality of electrical devices to charge the batteries coupled to the electrical devices and to decouple the current limiter by interrupting current flow through the current limiting circuit path to allow the current limiter to assume ambient temperature and thereby attain the characteristic high impedance so that current may again be caused to flow through the current limiting circuit path while the current limiter is in the high impedance state.