Casio MQ-24 series watch battery replacement
This may also apply to other Casio models with similar snap-on back covers. I believe the following batteries codes are all compatible: SR626SW / 377 Battery / SR66. I bought the Maxell SR626SW in bulk.
Parts & tools:
- replacement battery
- at least one small flathead jewelry screwdriver
- Optional second size: larger screwdriver for prying off the back cover more easily
1. Remove one strap.
Flip the watch face down on your table. We need to remove one of the straps (either side is fine) to gain access to the back cover. The strap holding pins are spring loaded: fix the end of your small-blade screwdriver on one of the pin’s end grooves closest to the watch body and press away from the watch body and into the strap, while pushing to the right slightly to disengage the pin from the hole in the body.
Careful the pin doesn’t go flying when you carefully remove your screwdriver.
2. Remove back cover.
Note the back cover is a press-fit, with two tabs acting a spring. We need to flex these tabs over the taper of the watch body—carefully pry up on one tab with your larger screwdriver blade until it pops loose. Careful not to damage the plastic of the watch body.
If you need more leverage, hang the screwdriver off the edge of your table. Sometimes I pry from the middle flat of the cover cover, rather than the tabs—not sure which method is better or more consistent.
Slowly pull the back cover off noting if the rubber gasket (o-ring) is stuck to it—don’t break this gasket. The two tabs on the other side should more easily come off the watch body now.
3. Remove gasket.
Lay the back cover down on its face. Lay the gasket on top of the cover, keeping the same side of the gasket oriented to the back cover. Reason: the gasket may have been pressed for years against the cover, we want to maintain the same orientation and “squish” to avoid introducing potential leaks.
4. Remove the battery.
The battery is held by a small springy metal lever. Press up on this lever to release the battery. Careful as the battery can go flying (it usually pops out 4″ or so off the table). Note the bottom lipped metal arm is not flexible. Don’t pry this bottom arm.
Full disassembled. Don’t confuse your old battery with the new one.
5. Insert new battery
Insert the new battery face up (+), tapered side (-) down. First insert at an angle, with the bottom of the button tucking under the bottom angled arm.
Use your finger to snap the top edge of the battery under the top straight arm, which is spring loaded. Ensure the battery is snug and doesn’t fall out.
6. Re-insert the gasket.
Replace the gasket in the same orientation you removed it. MOST CRITICAL that it fits in the dedicated groove of the watch body and doesn’t overhang inside or out. If this gasket is properly placed you will get moisture in your watch later.
7. Re-insert the back cover.
Inset the strap-side tabs first and carefully press down from left-to-right until the other tabs snap over the watch body tapers. MOST CRITICAL that you don’t dislodge the gasket from it’s groove.
Ensure the back cover is flush and parallel with the watch body. Visually inspect every side to make sure it’s flat, and that the gasket is not pinched or protruding.
8. Re-install the strap.
With the strap pin in the strap, insert one end of the pin into the watch body, then get the other end of the pin close to the watch body. With your small screwdriver, load the spring in the pin and carefully push into the watch body, ensuring it seats fully in the watch body hole. Give your strap a few tugs to ensure its seated and the same amount of pin and its grooves are visible as when you started (or compare to the other strap’s pin).
Related:
4. Remove the battery. …”Press up on this lever…”. I have misunderstood this. You mean “up” on the picture I now understand but I have first thought you ment one should lift up the lever. The result is that the lever stayed somewhat up so that the new battery is not pressed down correctly. But still there is electrical contact so that the watch is now functioning. I hope it will keep going…
Afterwords I several times looked at this video to understand:
https://www.youtube.com/watch?v=BdD3_gGvop8
“Press this lever to the side (in direction parallel to the upside of the battery) away from the battery” is my suggestion if you would like to alter the text.
Thank you for giving such clear advice and Hans for his additional tip. In the past I have bought a new watch rather than pay a shop to replace a battery, but this time I shall give it a try.
Very helpful – Thanks
Thanks for the tips!
If it wasn´t your page i wouldn´t open my watch!
Thanks!
Thank you!
Nobody in Walmart could change a watch battery. With your article I took my watch back off & changed my own battery standing at the jewelry counter!
Thank you, Jeff – from Tim in the UK.
HUGE Thanks! I am a complete klutz when it comes to mechanical repairs…still take way too long to remove and replace a bike tire after over 35 years of riding, including many centuries. Your PERFECT procedural, with exacting words and fab photos is precision.
Therefore, it is idiot proof, as I succeeded in minimal time by following each and every step with ZERO profanity…a first!
You are a mensch and an example of what is BEST about the internet.
Much appreciation,
T R Black
Irvine, CA
T R Black: I’m a bicycle racer—I should do a post on tips and tricks in tire changing!
It seems my rubber seal doesn’t fit inside the warch groove. It looks like an oval now. Is there anything I can do for that?
I have the same problem with one I recently changed the battery on—the seal appears to have expanded 10% and won’t fit again. I’d also like to source a replacement, but no luck finding one so far.
I have this watch and there is some different plasic shit movement signed CASÏO HKA-b inside, your one looks like Miyota.
Great stepby step instructions!
Just changed 2 dead casios
Thanks Jeff
Thank you so much! I never would have had the patience to figure this out on my own.
Thank you – perfect instructions.
Any updates on sourcing a gasket replacement? Mine is also expanded about 10% and the case won’t close without the gasket bulging on one side or another. Seems like a shame to throw out a working watch for such a fiddly little part.
I have just done this, and the best way to get the cover off is to insert a sharp knife under the cover (round part) adjacent to the clip, and gently lever.
Easy as pie
Great tutorial, thank you.
Thanks! I never would have figured it out on my own.
Excellent. Much better than a YouTube video that you have to keep pausing and rerunning.
As an Englishman in France, I echo the previous posts – good, clear instructions with precise photos. Success at first attempt!
Suggest pushing spring clip ‘away’ from the battery to release it.
Thanks for the time and effort neded to post this
Just successfully replaced my battery using your instructions – thanks so much! Delighted I don’t have to buy a new watch or pay someone to change the battery. Hooray for DIY and sustainability! Really, really appreciate your help! Take care!
Accurate and clear still photos of the process. Thank you
Hi Jeff,
Would greatly appreciate if you’re able to take measurements of your gasket so that those of us seeking a replacement know exactly what size to get.
Thank you kindly in advance!
Awesome blog Jeff. You are awesome.
Excellent clear instructions – mission accomplished successfully. Thanks
This is such a good tutorial! Thanks for putting it up!
Awesome instructions! You accomplished turning an impossible task into a simple and straightforward one. Thank you for posting!