Patent ID: 7786698

Claim:
A method of charging a battery, the method comprising: applying a charging current from a semiconductor device to a battery during a first battery charging time period; measuring a charging voltage level at the battery during the first battery charging time period; and controlling the charging current applied by an adjustable current source to the battery using the semiconductor device, wherein during the first battery charging time, a constant current is applied to the battery from the start of charging to when an upper threshold voltage level of the battery is reached without turning off the constant current, and wherein during a second battery charging time, the semiconductor device selectively provides a signal to turn off the charging current supplied by the adjustable current source, wherein a first voltage at the battery is measured during a time period when the charging current is turned on and a second voltage at the battery is measured during a time period when the charging current is turned off, and wherein the semiconductor device provides the signal to turn off the charging current when a difference between the first voltage and the second voltage is less than a threshold value.