How to change a Seiko kinetic battery

A Seiko 5M45-6A30 kinetic watch, ready to change the battery (capacitor).

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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.

A new Seiko battery (capacitor) for a kinetic-powered watch.

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!

A Seiko 5M45 kinetic movement, out of the watch case and in a movement holder.

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.

Unscrewing the rotor from a Seiko kinetic movement.
Seiko kinetic movement with the rotor removed.

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.

Unscrewing screws on a metal plate surrounding the battery.
A closer shot of the metal plate, removed from the watch movement.

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.

Removing the old battery with a pair of plastic tweezers.

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.

Replacing the red plastic insulator around the new battery.
Replacing the metal plate surrounding the new 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.

Replacing the gear underneath the rotor.
Replacing the rotor on the kinetic movement.

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.

A front dial-side look at the Seiko kinetic movement with the battery changed and working.

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