How to change a Seiko kinetic battery

The batteries (or rather capacitors) in Seiko kinetic/AGS watches are recharged by the wearer's wrist movement, but over the decades they lose their ability to hold a charge. When that happens, it's time to replace the battery/capacitor. It's not quite as easy as changing a regular quartz battery but with the right tools it can be done at home. Here's how…

Step 1

Get a new battery! They're unique to Seiko as they have a metal bracket attached to them but it's usually easy to source them from a reliable seller online. You can find the battery code number by looking at the page here on Mizeni for your Seiko watch movement. The movement code is the first four numbers/letters of the model number found on the back of the watch. As an example, the movement I'm working on in this guide is a Seiko 5M45.

Step 2

Open the case to expose the movement. For most watches this means unscrewing the caseback, for which you'll probably need a case opener. For some Seiko watches, however, the caseback is solid and you'll need to take off the crystal before completely removing the movement from the front. In this case, see my guide to opening Seiko monocoque watch cases. In either case, once you can see the back of the movement, you're ready to go!

Step 3

Remove the rotor. This is simply a matter of unscrewing the central holding screw with a fine screwdriver. Take off both the rotor and the gear wheel underneath it.

Step 4

There's a metal plate (clamp) surrounding the battery. Undo the two screws to remove this and the red plastic insulator underneath. They're tiny so you'll need both a very fine screwdriver and a pair of tweezers to move the screws to a safe place.

Step 5

Next, use plastic tweezers to remove the old battery and insert the new one. Do not use metal tweezers as they could short the new battery.

Step 6

Replace and screw down the red plastic insulator and metal plate, making sure you have them the right way round. They should fit tightly onto the plastic pin at the top left of the battery.

Step 7

Replace and screw down the rotor and its gear wheel underneath it. The pinion for the rotor is a square-ish shape, not round, so rotate the rotor and gear wheel a little until they fit snugly onto it.

Step 8

Now you can take a look at the dial side to check the seconds hand is moving. Congratulations! Close up the case, ideally using a blower to remove any dust that may have settled on the movement, and enjoy the satisfaction of breathing new life into your kinetic/AGS watch.

If you liked this, check out more articles about repairing, restoring and enjoying Seiko watches.