When changing a watch battery, the actual act is fairly simple, but there are many things you need to be aware of beforehand to keep from damaging the watch movement. If you open your watch case and can see the battery under a thin metal strap, you can be sure that the watch in front of you has a cell strap holding the battery in place. To change this type of battery, you should follow these instructions.
- A Flat Head Watchmaker’s Screwdriver
- A Watch Parts Tray
- Non-Magnetic Tweezers
- Plastic Tweezers
- Finger Cots
Once the back of the watch case is open, before you touch any part of the movement, you should put plastic finger cots on your fingers that might touch the watch movement. We recommend doing this because any dirt, oils or grease on your fingers can get on the movement and damage the inner workings of the watch if you touch it with your bare fingers. These finger cots will keep that oil from transferring to the watch.
When your fingers are protected, before you attempt to remove the watch battery you need to locate the battery number on the battery. You will probably have to spin the battery around under the cell strap to actually be able to see the number. Since batteries sometimes jump out of the watch case and get lost, it’s important that you note the number on the battery before removing it in case it does get lost, however if you move the battery around and still cannot see the number, you will have to wait until the cell strap is removed.
Usually the batteries are marked with their three digit number, but sometimes they are marked with a combination of letters and numbers. If it marked with letters and numbers you will need a Watch Battery Replacement Chart to find its 3 digit number. Use the watch battery number to get the right size replacement battery for the job.
To be able to remove the watch battery, you will probably have to remove the plastic movement ring that keeps the movement in place inside the watch case.
To remove the old battery, first you must remove the cell strap holding the battery in place. Take your screwdriver and begin to loosen the tiny screw holding the cell strap in place. Be very careful, sometimes there is tension in the cell strap that might cause the screw to spring away. When you have loosened the screw, remove it with your non-magnetic tweezers and put it and the cell strap in your parts tray so they don’t get lost.
After you have removed the cell strap, you will need to address the spring loaded arm holding the battery in place. If you couldn’t read the battery number earlier, now is the time to get it before completely removing the battery. Not all watches will have this arm, but to remove it take your flat head screwdriver again and gently pull the spring loaded arm back. Do not be concerned if the battery jumps out of the case. Once the old battery is free of the case, set it aside in case there is a problem and you need it later.
Take the new battery out of the package and pick the battery up with the plastic tweezers. Make sure that the side of the battery with the engraved number is facing upwards. Insert the new battery into the battery well. It usually works best to start by sliding one side of the battery in toward the arm first. When the battery is most of the way into the well, take your watchmaker’s screwdriver and gently pull the spring loaded arm back again and push the battery flat into well. Release the arm while holding the battery steady to ensure it holds the new battery in the watch case.
Now that the battery is back in place, you can replace the cell strap to hold the new battery securely. With your non-magnetic tweezers, pick up the cell strap and place it across the battery, and:
- If the strap ends halfway across the battery, simply align the screw hole in the strap with the one in the movement.
- If the strap has a tab that is inserted into a slot on the side of the battery, insert the tab into the slot and hold the cell strap down across the battery before aligning the screw hole in the strap with the one in the movement.
- Finally, if the strap is held in place with two screws, slip the end with a “C” hook under the screw that was partially loosened and then align the other end of the cell strap with the hole over the hole in the movement and tighten the screw over the “C” hook into place.
Very carefully, pick you the cell strap screw in your non-magnetic tweezers. Hold the screw so the threaded point is facing downward. Take your time placing the screw in the hole for the cell strap, this tiny screw can be easily lost so don’t feel like you need to rush through this step. Once the screw is in place, take your watchmaker’s screwdriver and tighten it all of the way into place, turning the screw clockwise.
When the battery is securely held in place by the cell strap, you can put the plastic movement ring back in place around the movement to keep it from moving in the watch case.
When you are done, you can replace the watch case back and begin to wear you watch again. For information on How to Close Your Watch Back, check out these videos.