Although Craftsman's chain- and belt-drive garage door openers employ a handful of different battery powered wireless openers, the company makes it pretty easy to determine what sort of battery you need when it's time for a change; each of the remotes uses a 3-volt 2032 lithium coin-cell battery. This applies to three-button remotes including the Craftsman 139.30499 as well as the 139.30498 and 139.30499, and remotes included in the box with openers. According to Craftsman, these little workhorses keep your opener working for about five years.
Getting In, Swapping Out
To access the battery compartment on a Craftsman garage door opener remote, use the flat end of the remote's visor clip to pry off the device's back cover. If the clip isn't handy, the blade of a flat-head screwdriver works fine.
Once you access the battery compartment, pop out the old batteries and refer to the instructions printed inside the battery cover or on the circuit board. These guidelines clue you in on the battery's proper polarity placement -- meaning whether you should face the positive side of the battery up or down. Keep an eye out for a plus sign on one side of the battery, which indicates the positive side. Typically, the battery goes positive side up.
Charging Up Keyless Entry
If you have a Craftsman wireless keyless entry pad, a wall-mounted alternative to pocket-sized openers, the battery changing process is a bit different. Instead of coin cells, these openers require a 9-volt battery. Changing it is as as simple as sliding off the bottom battery cover, removing the old battery and ensuring the contacts on the battery snap into the corresponding connectors. You'll know the keyless entry needs a new battery when the keypad lights become dim or do not light up when pressed.