A technique for detecting when a full charge for a cell pack is reached based upon sensing an actual temperature of the cell pack. The initial actual temperature is the first value stored as a reference temperature. During subsequent sampling events, the actual temperature is stored as the reference temperature when the actual temperature exceeds said reference temperature. A first value for each sample event is stored in a rollover memory when said actual temperature exceeds the reference temperature, and a second value is stored in the rollover memory when the actual temperature does not exceed the reference temperature. The occurrences of the first values is summed for a series of consecutive sampling events to derive a total. The total is compared to a predetermined limit, and if the total is greater, then charging of the cell pack will be discontinued.