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I am a big fan of watches and the Casio Marlin or Casio Duro watch is great value. The Casio MDV106 series watches look premium and if you buy a metal bracelet, they look much more expensive than the price. I think the Casio Marlin is the best value diver on the market today.
The challenge with the Casio’s is that at around US$50, paying to have the battery replaced can come out to close to half the price of the watch. So this is why it’s better to do it yourself.
This guide is to help other Casio Duro owners replace the battery on their Duro.
What you will need:
- SR626SW 377 Silver Oxide Watch Battery (these are what I use).
- a case back opening tool
- silicon grease for the gasket
Optional, if you don’t have the best eyesight, get yourself a loupe tool.
All up, it will cost you under $15 for what you need – and you will get multiple uses out of everything, good for an entire Casio Duro collection!
IMPORTANT: Your watch will not be 50M water resistant. If you do everything properly, it will still be water resistant for hand washing, rain, etc. but I can’t guarantee that it will be great for swimming. If you want that kind of assurance, you are better off getting the battery professionally replaced (or really, given the price, just buy yourself a new Casio Marlin).
Opening the Casio Duro / Marlin Diver Watch
To change the battery, you use the case back opening tool to grip into the notches on your Casio Duro. If you use the same tool as me, I have found I can hold the watch in one hand and turn the case back counterclockwise to open it. I use a plastic Ziplock bag to protect/ avoid scuffing the case while I open it (so the plastic bag sits on top, then use the tool over the bag). Make sure you get the teeth on the case back tool tight in the notches. You don’t need a lot of force to open it.
Replacing the Casio Duro / Marlin Diver Watch Battery
- Once the case is open, you will see a white piece of plastic protecting the internals (it’s also covering the battery).
- Use the tweezers. in the case back kit to lift out the plastic cover. Be careful not to lose the rubber gasket, it might fall out – if it does come out, set it aside, as we will silicon grease on it later to help with the seal.
- Looking at the Casio Duro, have the crown facing to your left. To the right of the battery is a fine spring. Gently use the tweezers that were in the case back kit I suggested to move the spring very gently right. The battery should just pop out!
- To put in the new Casio Duro battery (remember you need a SR626W Silver Oxide battery), again with the Crown on your left, put the battery in by positioning the battery under the metal holder on the left-hand side. The battery should sit at a slight angle. Using two hands, gently move the spring on the right-hand side while pushing down on the battery and it should lock into place.
- Use tweezers to gently remove the gasket seal. Then use the gasket grease to regrease the gasket before putting it back in your Casio Diver.
- Re-insert the plastic mechanism protector, it only fits one way – there’s a notch for the stem (crown pin). Push it in, it’s a friction fit so it will stay firmly in place.
- Re-attach the case back. Making sure to firmly hand tighten it using the case back tool.
- Set your watch!
- You’re done!
Remember, your Casio watch will not be 50M water resistant. If you do everything properly, it will still be water resistant for hand washing, rain, etc. but I can’t guarantee that it will be great for swimming. If you want that kind of assurance, you are better off getting the battery professionally replaced (or really, given the price, just buy yourself a new Casio Marlin).
Hope this helps someone else.
Any and all advice, guides, and reviews are unbiased and based on my personal experience. If you buy through affiliate links, I may earn commissions, which helps support my website. This does not have an impact on posts or my opinion of any reviewed products. If you find this post helpful and want to say thanks, please buy me a coffee or take a look at my book on Amazon. It keeps this page ad-free. Thank you!