Many watches are battery powered and needs to be replaced when the battery is used out. Watch batteries can be purchased at most drug stores, grocery stores, hardware stores or watch repair stores. Replacing a watch battery takes a few steps and a few tools, and most watches will need to be set once the new battery is in place.
Step 1: Place the watch face-down on a soft surface. Examine the back of the watch; locate the small indent on the side or the small slots, which is called a screw back case.
Step 2: Insert the flat blade of a small screwdriver, such as the one used for eyeglasses, at the small indent on the side of the watch if the case back is smooth. This is a snap back case.
Step 3: Use the small screwdriver to turn the small slots on the back of a screw back case. Alternatively, insert the metal tips of a tool called a case back wrench, which can be purchased at watch repair stores, into the slots and turn the wrench to open the watch.
Step 4: Open the case back. Remove the battery, which appears as a small, flat disc. If there is a clip holding the battery in place, use the blade of the screwdriver or your fingernail to lift the clip open to remove the battery.
Step 5: Insert a new battery and replace the clip, if necessary.
Step 6: Put the case back on the watch and use the screwdriver or case back wrench to turn the slots on a screw back case to their original position, closing the case back.
Step 7: Line up the indent on a snap back case with the notch on the side of the watch and press firmly to close the case back.
Step 8: Turn the watch back over and gently pull out the small knob on the side of the watch (the crown) until you hear a click. For watches with calendar settings, pull the crown out until you hear two clicks.
Step 9: Turn the crown clockwise till the correct time has been reached on the watch.
Step 10: Push the crown back in to the side of the watch and then turn several times to wind the watch.