News

Replacing the Battery

By David Christianson, Certified Master Watchmaker

When a quartz watch stops keeping time, the first assumption is the battery has to be replaced. That assumption is correct in most cases - very little else interferes with the accuracy and dependability of a quartz watch.

Quartz Watch Batteries

Quartz watches consist of a quartz oscillating crystal, an electronic circuit to drive the watch, a means of displaying time and a battery to power the whole system. The battery generally rests in a well or “nest”. The negative battery contact strap lies on the bottom of the well. The positive contact strap is attached to the side. In some models the hold-down strap itself acts as the positive contact.

Watch Battery

In either case, the negative and positive straps must be clear of any residue or contaminant. Wipe the straps with a clean piece of sharpened peg wood. If a stubborn residue remains, use a sharpened typewriter eraser.

If the battery is held with a strap and screw, loosen the screw carefully so the screwdriver doesn't slip out of the slot and damage the movement. Choose a sharp screwdriver the width of the screw diameter.

A battery may be held in position with a side-mounted spring tension contact instead of a strap. In this case, bite into the side of the battery with a small screwdriver blade and lift up. Be careful not to push the side-mounted positive contact down into the battery well - the watch won't work if the positive (+) contact doesn't touch the edge or side of the battery.

Replace With Care

Handle the battery with a pair of plastic tweezers (forceps). Oil and salt from your fingers can corrode the watch. If you can't completely insert the battery with tweezers, use a piece of Rodico or rubber finger cots on your fingertips to protect the battery. Long finger nails are good for pushing the battery into place.

Don't touch any part of the watch movement except the battery, its straps and its screws. And touch these only with tweezers - plastic for the battery and thin metal tweezers for the screws and retainer strap.

Digital Quartz Watches

In many quartz watches, mainly digital or a combination of analog and digital, the electronic circuit must be cleared before the battery is changed. This provision is called an AC - or all-clear - circuit. This is typically a small silver or gold-colored dot marked AC on the back of the movement.

To clear the circuit before changing the battery, use metal tweezers. Place one point of the tweezers on the dot and the other on the positive (+) side of the battery. Or push a spring tab onto the AC dot with a tweezer tip or probe. In either case, the watch display will likely become blank and be ready for a battery change. On some models, the display may remain, but the watch cannot be reset until the AC is cleared.

Be Clean

Cleanliness is the primary concern when changing the battery in a quartz analog watch. These watches use tiny motors that pulse or rotate once per second, causing the second hand to jump forward one second at a time. However, the gears are driven by such low power the slightest amount of dirt, lint or dried lubricant will stop the moving parts.

Be vigilant when removing dirt from the case back when opening the watch to change the battery. This is also the reason gaskets in the case back and crown must be replaced periodically.


Reprinted with permission from the Professional Jeweler Magazine. For more information, please visit the American Watchmakers-Clockmakers Institute (AWCI).