If your garage door opener has slow response times, or LED lights aren’t working, don’t flash, are dim, or you have to get close to the door to open, then it’s probably the battery.
Common openers are Craftsman, LiftMaster or Genie. Most use the small, round coin-cell or button-cell batteries of 3-volt lithium. And if the remote has extra functions like flashing LED lights, the device may take more than one battery, or it may need AA or AAA. A wall-mounted wireless keypad may use 9-volt batteries, and some use A23 alkaline batteries.
The coin battery has a code and voltage written on its face. The code usually indicates the physical size of the button battery.
The covers are removed by inserting a flat tool to pry it off, or some covers slide off, and others have screws to be removed.
A plus sign (+) on the device indicates the positive polarity side to direct which side is “up.”
Most of these batteries last between two and five years.