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This page describes how you can change watch batteries yourself.

Summary

Most watch batteries are easy to replace. This guide is for watches with a snap fit back and not a screw-on back. (That will be added later. A snap fit back is the commonest type.

Safety

To do this task you need a watch press otherwise you will either be unable to replace the back, or you might break the glass

Do dispose of the old battery properly. Keep batteries out of the way of children as they can be fatal if swallowed.

Snap-on watch backs

Equipment

A watch press with a watch in place face down

For a snap fit back you need:

a watch press. They are not expensive and can be bought on eBay or Amazon.

a watch maker's screwdriver. You need a flat-ended screw driver with a fine end to prise off the back.

a battery. Ideally you should use the internet to find out the battery that fits your watch. There are many different types of watch battery and they can be bought at a good hardware store, or Amazon or eBay. Of course if you cannot find out which battery is required, you can open the watch and see the battery that is in place.

A bright light or a head torch.

If you use reading glasses, you will need to use them. Magnifying glasses are helpful.

Isopropyl alcohol and tissues.

Removing the back

Clean the back of the watch with isopropyl alcohol giving particular attention to the join between the back and the body of the watch.

Lift off area on the watch back	Examine the edge of the back piece to find the small raised area where you will insert your screwdriver.Make a note or take a photograph of the back. Note the position of the winder when the writing is the right way up.
The lift off area is bottom left on this watch, but it is not always in this position	Carefully insert the screwdriver into the gap in the lift off area. Twist and the back should pop off.
Watch back showing O ring and also the notch for winder.	Examine the back. Look at the O ring and check it is undamaged. Identify the notch on the back for the winder. You will need to orientate the back so that the notch is over the winder when you re-assemble the watch.
You can see the battery and the spindle for the winder.	You should now see the inside of your watch. If you do not know what battery is needed, you can see the number on the old battery. In the photograph the battery number is 364. Renata is the make, but there are many other makes of battery. Sometimes you might find the battery is held in place by a metal finger secured by a tiny screw. Loosen the screw only enough to move the finger away from the battery. Replacing the screw if it comes out is tricky, but easier with a magnetised screwdriver.
Removing the battery. Needle is for illustration only	If you have the replacement battery, you can remove the old battery. The battery is held by retaining clips on edge of the battery. Sometimes it helps to use a sewing needle to push the battery out, starting from the outer edge.
Watch with battery removed	Here you can see the watch after the battery has been removed. You can now insert the new battery with the writing on the top as it was with the old battery. It should not require force to get the battery back in position.

Replacing the back

Your watch press should come with a selection of dies that screw into place. You need to select the underside die that supports/contacts the metal case only. Too small means that the edge of the die is pressing on the glass. Too big means that the main part of the die is in contact with the glass and the outer ring is not on the metal case. The choice is crucial to avoiding damage to the glass.

Ideal placement with die in contact with watch case only.
Die is too small and only in contact with the watch face.
Die is too big and pressing on the watch face.

The upper die will press on the watch back to snap into place. The die has to be at least as wide as the watch back, but the choice is less critical.

One the dies have been screwed onto the pegs of the watch press, carefully place the watch onto the lower die. The put the back onto the watch making sure that the cut-out for the winder shaft is over the shaft. Make sure the back is aligned evenly and is not tilted.

Watch in the watch press

Gently squeeze the handles together so that the upper die contacts the back and check that it is even. Then increase the force of your squeeze and you should hear/feel a snap as the back goes into place.