Your eufy Smart Lock will give you low-battery warnings for multiple weeks before it loses power. However, if your Smart Lock dies entirely before you can replace your batteries, your key will still work. You can use the key to lock and unlock the door.

If there is no key and the smart lock dies entirely, you can use a micro USB cable and a power bank to charge the smart lock in an emergency situation. The USB port at the bottom of the smart lock is designed for emergency charging.