Automatically switches off when the battery is fully charged to prevent overcharging too. Two-stage charging means the battery is first charged at a constant current up to a predetermined voltage limit. Then, the charger switches over to charging at a constant voltage before the current reduces itself automatically until charging is complete. A built in cable tie with Velcro strap on the back means you can wind the cable to the charger to reduce its length. Plus, this charger can be wall mounted for space saving storage.