You can change a Timex Ironman battery yourself with a coin, a small screwdriver, and about five minutes
Most Timex Ironman watches use a standard coin-cell battery (usually CR2032 or CR2016) that you can replace at home without tools beyond what you already have. The back of the watch unscrews like a jar lid. Once you open it, you slide out the old battery, drop in the new one with the positive side facing up, and screw the back on again. The whole job takes longer to find a coin than to do it.
The battery lasts between two and five years depending on how often you use the backlight and alarms. When the watch starts losing time, running slow, or the display dims, the battery is usually dead. You do not need to go to a jeweler or send it anywhere—you can do this in your kitchen.
Key Takeaways
- Timex Ironman watches almost always use a CR2032 or CR2016 coin-cell battery that you can buy at any drugstore or supermarket for two to five dollars.
- You need only a coin (dime or penny) to unscrew the caseback and a small flathead screwdriver to pry it open if the coin does not grip well enough.
- The battery slides into a metal holder with the shiny side (positive terminal) facing up toward the watch face, and the flat side facing down.
- After you close the caseback, test the watch by pressing the light button and checking that the display is bright and the time is correct.
What battery your Ironman uses and where to buy it
The vast majority of Timex Ironman models use either a CR2032 (the most common) or a CR2016 battery. The CR2032 is thicker and lasts longer. If you are not sure which one your watch takes, look at the caseback—the model number is printed there, and you can search that number on the Timex website or call their customer service line to confirm. You can also open the watch and look at the battery itself; the size is stamped on it.
Buy the replacement at any pharmacy, supermarket, or electronics store. CVS, Walgreens, Target, and Walmart all stock CR2032 batteries in the watch or battery aisle. A single battery costs between two and five dollars. Buy two if you can—having a spare means you will not have to go back out when the next battery dies. Make sure you buy the right size; CR2032 and CR2016 look similar but are not interchangeable.
Gather your tools and prepare your workspace
You need very little: a coin (a dime or penny works best), a small flathead screwdriver, and a clean, flat surface with good light. A kitchen table or bathroom counter is fine. Lay down a paper towel or small cloth so you do not lose the tiny screws or the caseback itself.
Before you start, wash your hands or put on clean cotton gloves. The oils on your skin can damage the battery contacts and shorten battery life. If you do touch the battery, wipe it with a clean, dry cloth before you put it in the watch.
Open the caseback by unscrewing it
Hold the watch face-up in one hand. Look at the back—you will see a circular metal disc with small notches or grooves around the edge. This is the caseback. Place your coin (dime or penny) into one of the notches and turn it counterclockwise, the same way you would unscrew a jar lid. Turn gently but firmly; do not force it or you may strip the grooves.
After two or three full turns, the caseback will loosen. Unscrew it the rest of the way by hand and set it aside on your cloth. Do not lose it. If the coin does not grip well enough, use a small flathead screwdriver instead—place the tip in one of the notches and turn counterclockwise. Again, turn gently.
Remove the old battery and install the new one
Inside the caseback, you will see a metal battery holder with a small coin-cell battery sitting in it. The battery looks like a tiny silver disc. Using your fingernail or the edge of a plastic spoon, gently pry the old battery out of the holder. It should come free with light pressure. Set it aside.
Before you install the new battery, look at the holder. You will see a small metal tab or spring on one side. The battery must sit with the shiny, flat side (the positive terminal) facing up toward the watch face, and the flat side facing down into the holder. Slide the new battery into the holder, positive side up. It should sit flat and snug. If it feels loose or tilted, remove it and reposition it.
Close the caseback and test the watch
Hold the watch face-up and align the caseback with the opening. Press it down gently and then use your coin or screwdriver to turn it clockwise until it is snug. Do not overtighten—you want it sealed but not stripped. Turn until you feel resistance, then give it a quarter turn more.
Now test the watch. Press the light button (usually on the left side of the watch) and check that the display lights up brightly. Look at the time and make sure it is correct. If the display is dim or does not light at all, the battery may not be seated properly. Open the caseback again and check that the positive side of the battery is facing up.
Common mistakes and how to avoid them
The most common error is installing the battery upside down. If you close the caseback and the watch does not work, the battery is almost certainly backwards. Open it again and flip the battery so the shiny side faces up. Another mistake is touching the battery with bare hands and leaving oils on the contacts. Wipe the battery with a clean cloth before you install it, and try not to touch the shiny side.
A third mistake is overtightening the caseback. If you turn the coin too hard, you can strip the grooves and make it impossible to open the watch again without damaging it. Turn until snug, then stop. If the caseback is leaking water after you close it, you may have overtightened and cracked the seal. Open it gently and reseat the caseback with less force.
Finally, do not assume the battery is dead just because the watch is running slow. Timex Ironman watches sometimes run slow when the battery is low but not completely dead. If the display is still bright and the watch responds to button presses, the battery may just need replacing soon. If the display is dim or the watch does not respond, the battery is dead and needs to come out now.
Frequently Asked Questions
Can I use a different battery size if I cannot find the right one?
No. CR2032 and CR2016 are not interchangeable. If you use the wrong size, the battery may not sit properly in the holder, the watch may not work, or the caseback may not close. Buy the correct size for your model. If your local store is out of stock, order online and wait a few days rather than guessing.
What do I do if the caseback is stuck and will not unscrew?
Try wrapping the coin in a thin cloth or rubber band to improve grip. If that does not work, use a flathead screwdriver instead. Place the tip firmly in a notch and turn slowly. If it still will not budge, the grooves may be stripped from a previous attempt. Stop and take the watch to a jeweler rather than risk breaking the caseback.
How long does a new battery last in a Timex Ironman?
Most batteries last between two and five years. If you use the backlight frequently or set many alarms, the battery will drain faster and may last only two years. If you rarely use the backlight, it may last four or five years. When the watch starts running slow or the display dims, it is time to replace the battery.
Is it safe to open my Ironman watch if it is water-resistant?
Yes, but you must reseal it properly. Timex Ironman watches are water-resistant, not waterproof, and the seal depends on the caseback being closed correctly. After you install the new battery, screw the caseback on snugly and test the watch before you wear it in water. If water gets inside, the watch may stop working and the circuit board may corrode.
What if the watch still does not work after I put in a new battery?
First, open the caseback and check that the battery is seated correctly with the positive side facing up. If it is, remove the battery, wipe it clean with a dry cloth, and reinstall it. If the watch still does not work, the problem may not be the battery—the circuit board or display may be damaged. At that point, contact Timex customer service or take the watch to a jeweler for repair.