Most systems are battery powered with batteries in each lock. A small number use wireless power, transmitted from the keycard, or wired low voltage power, which would typically have battery backup. If a battery is dead, the lock will not open unless there is a physical override, or the battery is replaced.

The vast majority of modern hotel electronic door locks are powered by standard alkaline batteries, typically four AA or AAA cells housed within the internal compartment of the lock assembly on the room-side of the door. This design is chosen for its extreme reliability; because the locks are not hard-wired into the building's electrical grid, they remain fully functional during power outages or "brownouts," ensuring guests are never locked out or trapped during an emergency. These batteries generally last between 12 and 18 months, depending on the frequency of use. To prevent a guest from being stranded by a dead battery, the locks are programmed with a "low battery" warning system—usually a specific flashing LED pattern (like a blinking yellow or red light) that alerts the housekeeping or maintenance staff to swap the cells before they fail. In the rare event that a battery does die completely, staff can use a portable "jump-start" device or a physical master key to provide temporary power or manual override. Some newer, high-end "smart" locks use Power over Ethernet (PoE) or hard-wiring, but the battery-operated standalone unit remains the global industry standard for cost-efficiency and security.