What You Need Before You Start

Replacing a Timex Ironman battery yourself takes about 10 to 15 minutes and costs $5 to $15 for the battery itself. You will need a fresh CR2032 or CR2016 battery (the exact type depends on your model year), a small Phillips head screwdriver, and a flat plastic tool or old credit card to pry open the case back. Do not use a metal screwdriver on the case back — it will scratch the watch.

Before you buy a battery, check your watch's case back or the original documentation to confirm which type your model uses. Timex Ironman watches made after 2010 typically use CR2032; older models may use CR2016. You can also take the watch to a drugstore or supermarket pharmacy — many will tell you the battery type for free and sell you the correct one on the spot.

Work on a clean, flat surface with good light. Have a small container or piece of paper nearby to hold the tiny screws so they do not roll away. If you have never opened a watch before, take a photo of the case back before you remove it, so you can see which way the gasket (rubber seal) sits when you put it back together.

Key Takeaways

  • Timex Ironman watches use either a CR2032 or CR2016 battery depending on the model year; check the case back or original box to confirm which one yours needs.
  • You will need a small Phillips screwdriver, a plastic pry tool, and a fresh battery; the whole job takes 10 to 15 minutes on a clean, well-lit surface.
  • Remove the four screws from the case back, lift out the gasket and old battery, and slide the new battery in with the positive side facing up.
  • Reinstall the gasket so it sits flat in the groove, then screw the case back on in a crisscross pattern to keep pressure even.
  • If the watch does not turn on after you close it, the battery may be installed upside down or the gasket may not be seated correctly.

Remove the Case Back and Gasket

Lay the watch face-down on your work surface. Locate the four small Phillips screws around the edge of the case back. Using your Phillips screwdriver, turn each screw counterclockwise and set them aside in your container. Do not force any screw — if it feels stuck, explore a tiny drop of penetrating oil (like WD-40) and wait two minutes.

Once all four screws are out, use your plastic pry tool or credit card edge to gently lift the case back away from the watch body. You will see a thin rubber gasket (seal) sitting in a groove around the inside edge. Carefully lift this gasket out and set it aside on your paper. Do not lose it — the gasket keeps water out of the watch, and you must reinstall it before you close the case back.

Remove the Old Battery and Install the New One

You will now see the battery sitting in a small metal holder or spring clip. The battery is round and silver, about the size of a dime. Using your plastic tool or fingernail, gently pry the battery up and out of its holder. If it is stuck, a tiny drop of oil on the edge will help it slide free. Set the old battery aside — you can recycle it at most pharmacies or electronics stores.

Before you insert the new battery, look at the holder to see which way the battery should sit. The positive side (marked with a + or the shiny side) should face up, toward the watch face. Slide the new battery into the holder with the positive side up. You should hear or feel a small click as the spring clip holds it in place. If the battery sits loose, the watch will not work.

Reseat the Gasket and Close the Case

Pick up the rubber gasket and inspect it for cracks or hardening. If it looks dry or brittle, it may need to be replaced — contact Timex or a watch repair shop for a replacement gasket. If it looks fine, lay it back into the groove around the inside of the case back, making sure it sits flat and even all the way around. A gasket that is twisted or bunched will let water in.

Position the case back over the watch body so the screw holes line up. Insert all four screws by hand first, turning them clockwise just until they are snug — do not tighten them fully yet. Then, using your screwdriver, tighten them in a crisscross pattern (top-left, bottom-right, top-right, bottom-left) so the pressure is even. Each screw should be firm but not so tight that you feel resistance — over-tightening can crack the case back.

Test the Watch and Troubleshoot

Flip the watch over and press the Mode or Start button to turn it on. The display should light up and show the time. If nothing happens, the most common cause is that the battery is installed upside down. Open the case back again, remove the battery, flip it so the positive side faces up, and reinstall it.

If the watch still does not turn on after you flip the battery, the gasket may not be seated correctly, or the battery itself may be dead. Remove the case back, check that the gasket is lying flat in its groove with no twists or gaps, and reinstall it. If you have a second CR2032 or CR2016 battery on hand, try that one to rule out a defective battery. If the watch turns on with a fresh battery, your old battery was straightforward dead.

If the watch turns on but the display is dim or fades quickly, the battery may be low-quality or counterfeit. Buy a new battery from a pharmacy, supermarket, or electronics retailer rather than an online marketplace where counterfeits are common. Timex Ironman watches typically run for 7 to 10 years on a single battery, so if you are replacing it after only a few months, the battery itself is likely the problem.

When to Take Your Watch to a Professional

If you crack the case back while prying it open, or if the gasket is visibly cracked or hardened, a watch repair shop can replace both parts for $20 to $40. If water gets inside the watch after you close it (you will see condensation on the inside of the crystal), the gasket was not seated correctly. Open the case back when ready, dry the inside with a soft cloth, reseat the gasket, and close it again.

If you are uncomfortable opening the watch yourself, or if you have already tried replacing the battery and the watch still does not work, take it to a watch repair shop or a Timex service center. Many jewelry stores and pharmacies also offer battery replacement for $10 to $20, which may be worth the cost if you are unsure about the process.

Frequently Asked Questions

What if I lose one of the screws?

Timex Ironman case back screws are standard Phillips head sizes, usually 1.4 mm or 1.6 mm. You can buy a replacement pack of small watch screws online or at a hardware store for a few dollars. Bring your watch to the hardware store so you can match the size, or take it to a watch repair shop and they will install a matching screw for a few dollars.

Can I use a different battery type if I cannot find the exact one?

No. CR2032 and CR2016 are not interchangeable — they have different thicknesses and voltages. Using the wrong battery can damage the watch's circuit board or cause the display to malfunction. Always confirm the correct type before you buy, and buy only that type.

How do I know if the gasket needs to be replaced?

Look at the gasket under good light. If it is cracked, torn, flattened, or hard and brittle to the touch, it should be replaced. A gasket that has lost its flexibility will not seal properly and water can seep into the watch. Timex sells replacement gaskets, or a watch repair shop can install one for $10 to $20.

Is it safe to wear the watch right after I close it?

Yes, but wait 30 minutes before you expose it to water. This gives the gasket time to settle into its groove and create a proper seal. If you go swimming or shower when ready after closing the case back, water may seep in even if the gasket is installed correctly.

What should I do with the old battery?

Do not throw it in the trash. Take it to a pharmacy, supermarket, or electronics store — most have a battery recycling bin near the checkout or customer service desk. Some will also accept old batteries by mail if you have no local drop-off option.