MVMT watches run on standard quartz movements, and when the seconds hand starts skipping two-second intervals or stops entirely, the battery is the first thing to check. Replacing it takes about ten minutes with the right tools, and it costs roughly $3 to $8 in parts versus the $15 to $45 a shop would charge.
The catch is that MVMT cases are pressed shut, not screwed. That means you need a case-back knife or a friction-ball opener, not a screwdriver. The wrong tool will gouge the case back and leave permanent marks.
What You Need Before Opening the Case
MVMT watches use a standard round snap-off case back. The battery inside is almost always a 371 or 377 button cell, but you should confirm the movement number before ordering. The movement is stamped on the circuit board, visible only after the case is open.
Tools and parts to gather:
- Case-back knife or a friction-ball opener (a flat screwdriver will damage the case)
- Case holder or a soft cloth to protect the crystal
- Replacement battery — most MVMT models take a 371 (SR920SW) or 377 (SR626SW) silver-oxide cell
- Tweezers with non-metal tips (plastic or ceramic) to handle the battery
- A toothpick or wooden peg for releasing the battery clip
- Latex or nitrile gloves — skin oil accelerates battery corrosion
The Seizaiken 377 SR626SW silver-oxide battery is a common drop-in replacement for MVMT watches. It’s mercury-free, rated at 1.55V with 30 mAh capacity, and the leakage resistance matters because a leaking cell can destroy the movement in weeks.
Checkpoint before you start: Confirm the watch is actually dead. Pull the crown to the time-setting position and turn it. If the hands move, the gear train is fine and the problem is electrical — almost certainly the battery. If the hands are frozen or grinding, stop here and take it to a watchmaker.
Opening the Case Back Without Damage
MVMT case backs have a small notch or a smooth edge depending on the model year. Place the watch face-down in a case holder or on a folded cloth so the crystal isn’t bearing weight.
Insert the case-back knife into the notch at a shallow angle — nearly parallel to the case back, not perpendicular. Apply steady downward pressure while twisting the blade. You should feel the back pop free with a slight click. If the back doesn’t release with moderate force, rotate the watch and try a different spot along the seam.
Common failure point: People insert the blade too deeply and scratch the movement or the inside of the case back. The blade should only penetrate the seam between the case back and the case middle — roughly 1mm, not deeper.
Once the back is off, set it aside with the gasket facing up. The rubber gasket sits in a channel on the case back or on the case itself. If it’s cracked, dried, or stretched, order a replacement before closing the watch back up.
Removing the Old Battery
Look for the battery clip — a small metal tab holding the button cell against the circuit board. Do not pry the battery out from underneath the clip with a metal tool. Use a toothpick or wooden peg to push the clip aside just enough to release the battery, then let the cell fall out onto the cloth.
Verify the battery code before ordering a replacement. The old battery has its code printed on the face. If it reads “371” or “SR920SW,” you need a 371. If it reads “377” or “SR626SW,” you need a 377. These two are not interchangeable — they have different diameters and thicknesses, and forcing the wrong one into the clip will break the contact.
Inspect the battery compartment for white powder or crusty residue around the contacts. That’s corrosion from a leaking battery, and it means the movement may already be damaged. If you see corrosion, do not install a new battery. The new cell will drain quickly or fail to make contact. This is the point where a DIY repair stops and a professional service begins.
Installing the New Battery and Closing the Case
Drop the new battery into the compartment with the positive (+) side facing up, matching the orientation of the old cell. The positive side is the smooth face, and the negative side has the printed code. Push the clip back over the edge of the battery until it snaps into place.
Verification step: Before closing the case, set the time with the crown and confirm the seconds hand starts moving. If it doesn’t, the battery may not be seated, or the clip isn’t making contact. Try pressing the clip down gently with a toothpick. If the hand still doesn’t move, the movement is likely damaged and needs professional attention.
When the watch is running, check the gasket. It should sit evenly in its channel with no kinks. Press the case back into place with your thumbs, applying even pressure around the entire circumference. You should hear a uniform click as it seats. If one side pops up, remove it and reseat the gasket before trying again.
Water resistance note: MVMT watches are not dive watches. Most models are rated for splash resistance only, and that rating depends entirely on the gasket. If the gasket is old or damaged, the watch will not survive hand-washing or rain after the battery change. Replacing the gasket is a $2 to $5 part and a five-minute job — skipping it turns a simple battery swap into a moisture-damage risk.
When to Stop and Call a Professional
The battery replacement is complete when the seconds hand runs continuously and the case back is fully seated. But three situations require escalation:
1. Corrosion in the battery compartment — the movement needs cleaning and possibly repair
2. The seconds hand doesn’t move after a new battery is installed — the movement is dead, not the battery
3. The case back won’t reseat evenly — the gasket is pinched or the case back is bent
A professional watchmaker will charge $40 to $80 for a battery replacement on a fashion watch, which feels steep against the $5 part cost. But that price includes a new gasket, pressure testing, and a movement check. If the movement is damaged, the repair cost will exceed the watch’s value — MVMT watches retail between $95 and $180, and a movement replacement runs $50 to $120. In that case, the practical decision is often to replace the watch rather than service it.
FAQ
What battery does an MVMT watch take?
Most MVMT models use a 371 (SR920SW) or 377 (SR626SW) silver-oxide button cell. The exact code is printed on the old battery and visible after opening the case back.
How do I open an MVMT watch without a case-back tool?
A case-back knife or friction-ball opener is required. A flat screwdriver or knife blade will scratch the case back and can bend the case edge, making the back impossible to reseat properly.
Is an MVMT watch water-resistant after a battery change?
Only if the gasket is intact and properly seated. MVMT watches have limited water resistance, and the gasket degrades over time. Replace the gasket during a battery change if there are any signs of cracking or flattening.
How much does it cost to replace an MVMT watch battery at a shop?
Most jewelry stores and watch repair shops charge $15 to $45 for a battery replacement on a fashion watch. The DIY cost is $3 to $8 for the battery plus the one-time cost of a case-back tool.
How long should an MVMT watch battery last?
A silver-oxide battery in a quartz watch typically lasts two to three years. A lithium battery can last four to five years. If the battery dies in under a year, there may be a problem with the movement or the watch may have been sitting in inventory for a long time before purchase.
The We Know Watches editorial team brings together over 40 years of combined watch collecting, trading, and repair experience. Our editors have owned and handled watches from every major brand — from entry-level Seiko 5s to Rolex, Omega, Patek Philippe, and independent Swiss watchmakers. We’ve bought and sold at auction, worked with authorized dealers, visited manufacturing facilities in Switzerland and Japan, and serviced hundreds of movements ranging from the Seiko 7S26 to the Longines L888. Every guide and review we publish is based on hands-on experience, original research, and consultation with professional watchmakers. We do not accept payment for reviews, and we clearly disclose when we use affiliate links.