Casio G-Shock GW-7900B. Battery change.

Recently, I’ve been writing articles about smartwatches with the best battery life, so I thought, why not write an article about my beloved Casio G-Shock GW-7900B watch.

Interestingly, this watch has outlasted many of my smartwatches. I’ve been using this watch intermittently from 2010-2011. For example, I bought a Garmin Fenix 3 in 2016, which I used for over half a year, and then returned to Casio G-Shock GW-7900B.

My story with Casio G-Shock GW-7900B

Casio G-Shock GW-7900B battery

Fun fact, I bought it cheap, for 40 USD used one. And after almost one year I understood why it was so cheap. The watch by it looks looked in mind condition. But after a month of use, it stopped. I remember reading forum posts about a never-dying rechargeable battery and how I tried to charge it outside for some days.

As I found out later, the battery in the watch was inserted was even smaller than it should be, so it was not suitable for charging from the solar panel. This battery was put in because the original battery suitable for use with this watch costs quite a lot. Almost half the price of the watch.

The original Casio G-Shock GW-7900B battery is CTL1616, costing between 15 USD and 25 USD. You can buy one on for 17.18 USD. But if you need the watch now until said battery arrives, you can put in a CR1616 (you can find it in almost all the bigger shops), which is the same size. It just won’t be charged by solar power.

How to change Casio G-Shock GW-7900B battery

I will create a short tutorial on how I changed the battery for my watch with basic tools. Keep in mind that you take full responsibility yourself. If you don’t want to take a risk, you can always take the watch to a watch workshop.

If you decide to do this procedure yourself, this list of tools can help you:

  • Small Philips head screwdriver
  • Paper clip
  • Paper staple

The first photo will show what tools were used. I only have them, so don’t judge me.

casio g shock battery change

G-Shock battery change steps

Step 1. Removing the wrist guard

If your case has them, you must remove the protective guards before changing the battery.

In my case, the screws did not turn all the way. I had to pull them with the plastic part gently. Like in the photo below.

In this way, remove the wrist guards.

Step 2.

Unscrew 4 screws and remove the protective cover. Be careful not to lose the protective membrane.

Step 3.

When you remove the first protective cover, you will see plastic protection. Gently take it off. It has a hole for spring. Don’t lose that spring.

Step 4. Opening of the battery support mechanism.

casio g shock battery change battery support mechanism

Remove the information sticker and put it somewhere nearby. You can stick it back later. As you can see in the attached photo, there is a small latch for opening the battery holder. To open it, you need a thin but quite strong metal. For this, I used an unfolded paper staple.

Below is a close-up photo of how I opened the mechanism.

Casio g shock battery change open mechanism

Step 5.

casio g shock battery change open mechanism taking out battery

When the battery holder is opened, the battery automatically pops up a little bit, and by using my fingers, I gently slide the battery out of the Watch mechanism.

Casio g shock new battery installation

After that, just put in a new battery and gently close the battery holder mechanism with your fingers.

When inserting a new battery, do the same steps in reverse. Just don’t forget about the little spring, rubber membrane, and plastic cover.

Casio g shock AC restart

And I don’t do the Casio watch by restarting the AC buttons, but if the watch is behaving strangely, you can do it with a paper clip like in the picture below.

Casio g shock AC restart

You need to hold it for more than 2 seconds, and after that, your watch will be restarted, and the time will start counting again from the default time (in my case, 12:00).

Casio G-Shock buttons do not work after battery change

This situation could have happened for the following reasons.

  • The entire clock mechanism was removed from the case.
  • The wrong type of battery is installed, or the battery is old and low.
  • You forgot to put a plastic cover, which presses the clock mechanism.
  • Somehow you break the watch mechanism.

If you remove the watch mechanism from the watch case, inspect if the buttons touch the watch mechanism when pressed. Below is a photo of where to look.

casio g shock buttons dont work

If you see the mechanism touching when the buttons are pressed, you can try to perform an AC restart.

Does your watch is charged by a solar battery? Inspect the display to see if CHG is not flashing. If so, it can be some error because of this. You can try to leave it for the night in a dark area, and the buttons can start working after this procedure.

If the procedure still failed and you broke the watch, you can purchase a new Casio G-Shock GW-7900 from here.

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I hope everything went well and you have successfully replaced the Casio G-Shock GW-7900B battery. The same principle of battery replacement also works in other G-Shock watches.


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