An overcharging protection system monitors the temperature of a cable used to transfer electricity from a power source to a personal electronic device. If the temperature as detected by a thermometer device of a sensor crosses a threshold, a bridge of a cutoff device is retracted disconnecting the two pieces of the cable to prevent any further increase in temperature due to charging. The thermometer device and cutoff device are housed in the interior space of a casing. The casing attaches to the cable.