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SEIKO SKA371 Kinetic battery replacement

A few months ago I had purchased a used SEIKO SKA371 watch. I noticed that I was not able to charge it up to a full charge which is 4 to 6 months. My wife has the SKA367 and had no problem keeping it fully charged. So I decided it might be time to change the battery. Some people call it a battery, power cell or capacitor. I found the kit I needed a 30235MZ, on EBay for around $15

Below are some pictures and notes on how I changed the battery.

Watch and new battery kit.

The kit contains the battery, battery insulator and battery retainer.

You will only need a couple of tools.

  • Watch case back opener
  • Small screw driver

Not mandatory but very helpful

  • Magnifying glass or jeweler's loop
  • Tweezers
  • Magnet if you drop a screw
  • Well lighted work place

Here is a pic of the case back removal tool picked up at Harbor Freight for $5.00.

Remove the watch band.

Unscrew the case back.

You will see the counter weight that turns to drive the generator to charge the battery.
The counter weight is held on by a single screw.
Gently hold the counter weight from turning and remove the center screw.

Underneath the counterweight is a single gear. You will notice that the gear is different and that there is a top and a bottom. The top part is higher in the middle. Make sure you replace it the same way you remove it.

Here is a picture with the counter weight removed.

Here is a picture with the counter weight and the gear removed.

There are two screws that hold the battery retainer and battery in place.

Here is a close up of the two screws holding in the battery retainer, green arrows.
There are also two indexing pens, blue arrows.

Remove the two screws and lift the battery retainer off.
The battery insulator simply lifts off also.

Here is a picture with the battery retainer and insulator removed.

Here is a close up of the battery and how it is aligned. Notice how the right metal ear fits in the plastic guide.

Lift the battery out and set aside and make sure not to get it mixed up with the new battery.

Here is a picture with the battery removed.

Here is a close up of the battery compartment.

You are now ready to install the battery.

  1. Install the battery making sure the right leg fits in the plastic groove.
  2. Install the battery insulator and align the holes over the plastic indexing pins.
  3. Install the battery retainer. The retainer is slightly bowed in the middle to keep the battery under tension

Probably does not matter but I installed the right screw first and then you will have to hold the retainer down as you insert the second screw.
NOTE: When putting in the second screw, the retainer can act as a spring board launching that TINY screw into outer space. This is where the magnet may come in handy.

I removed the case back O-ring and lubed it with a very thin coat of silicone grease. I probably should have ordered a new one but I was not able to verify the correct size. After removing the case back I measured the O-ring groove it sets in and came up with 30.49mm inner diameter and 32.60mm outer diameter. So it a new one should be in that ball park. Had I it to do again, I would not have removed the O-ring but simple put a very slight coat of silicone grease on the exposed O-ring and left it at that.

Before, no matter how much I would try to charge the battery I could never get the second hand to show more than 20 seconds of charge which would be about one month of charge. While I had the case back off and the new battery was in place, I GENTLY spun the counter weight like 250 times. My second hand then showed 30 seconds with is between 4 and 6 months of charge. So it defiantly needed a new battery.

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