A dead Tissot doesn’t always mean a trip to the jeweler. Most quartz Tissot models—from the PRX quartz to the Gentleman and Le Locle—run on standard button-cell batteries that a careful owner can replace in about ten minutes with the right tools. The catch is knowing which battery your specific movement uses, how to open the case back without scarring it, and when to stop and hand the watch to a professional.
Here is the direct answer: identify the movement caliber (printed on the movement or listed in the manual), order the matching silver-oxide battery, open the case back with the correct tool, replace the cell, and close the watch with a gasket check. If the watch has a screw-down crown or a rated water resistance above 50 meters, you should strongly consider having a professional do the job to preserve the seal.
Before You Open Anything: Identify the Movement and Battery Code
Tissot does not print battery codes on the case back. The battery reference is tied to the movement caliber, which is stamped on the bridge of the movement itself and visible only once the case back is off. That creates a chicken-and-egg problem for first-timers, but there are two practical workarounds.
Option A: Look up the caliber by model. Tissot’s official website lists the movement caliber for each current model in the product specifications. The PRX quartz, for example, uses the ETA F06.115 caliber. The Gentleman quartz uses the ETA F06.411. Older Tissot quartz models often use ETA calibers like the 955.412, 955.432, or 956.412.
Option B: Open the case back first, then order the battery. If you already have the tools, opening the case back to read the caliber is the most reliable path. Once you know the caliber, cross-reference it against a battery chart.
| Tissot Caliber | Battery Code | Voltage | Common Models |
|---|---|---|---|
| ETA F06.115 | Renata 371 (SR920SW) | 1.55V | PRX quartz, Gentleman quartz |
| ETA F06.411 | Renata 371 (SR920SW) | 1.55V | Gentleman quartz, Tradition quartz |
| ETA 955.412 | Renata 377 (SR626SW) | 1.55V | Vintage Tissot quartz (1980s–1990s) |
| ETA 956.412 | Renata 364 (SR621SW) | 1.55V | Slim vintage quartz models |
| ETA 901.001 | Renata 321 (SR616SW) | 1.55V | Older two-hand quartz models |
The Seizaiken 377 SR626SW silver-oxide cell covers the most common vintage Tissot calibers. It is a 1.55V, mercury-free cell with a 30 mAh nominal capacity, which is the correct specification for movements designed around the 377 standard.
Why silver-oxide matters: Tissot quartz movements are designed for 1.55V silver-oxide cells. Alkaline alternatives (usually 1.5V) have a different discharge curve and can leak more readily. The voltage difference is small, but the leak risk is not—silver-oxide cells have far better leakage resistance, which matters in a watch you plan to keep.
Tools and Preparation: What You Actually Need
Tissot uses two types of case backs across its quartz lineup: snap-off (pressure-fit) and screw-down (threaded). The PRX quartz uses a snap-off back. Many dressier quartz models use screw-down backs. You need to know which type you have before choosing a tool.
For snap-off backs: A case back knife or a case back remover tool with a flat, thin blade. Do not use a kitchen knife, a flathead screwdriver, or any improvised wedge—these will gouge the case and can slip into the movement.
For screw-down backs: A case back wrench with adjustable pins, or a rubber ball (the friction method). The rubber ball works surprisingly well on lightly tightened backs and carries zero risk of scratching. For backs that are stuck, a proper wrench with the correct pin spacing is the reliable option.
Additional supplies:
- Replacement battery (matched to the caliber)
- Plastic tweezers or a wooden toothpick (never metal tweezers—they can short the circuit)
- A small dab of silicone grease for the gasket (optional but recommended)
- A clean, soft cloth to work on
A note on tool quality: A cheap case back opener that slips is not a bargain. One slip can scratch the case back, deform the gasket channel, or nick the movement. If you plan to open more than one watch, invest in a tool with a solid grip and replaceable blades. If this is a one-time job, a rubber ball for screw-down backs or a basic case knife for snap-offs is sufficient.
Step-by-Step: Replacing the Battery
Step 1: Prepare the Workspace
Work on a soft cloth or a watch mat. Good lighting is essential—you will be handling a cell smaller than a fingernail. Have the replacement battery out of its packaging and within reach before you open the watch.
Step 2: Open the Case Back
For snap-off backs: Insert the case knife into the small notch where the case back meets the case. Apply firm, steady pressure to pry the back upward. It should pop off with a distinct click. Work around the perimeter if it does not release on the first attempt—do not force one point.
For screw-down backs: Place the case back wrench pins into the corresponding notches or slots on the back. Turn counterclockwise. If the back is tight, apply downward pressure while turning to prevent the pins from slipping. A rubber ball can work here: press it firmly against the back and rotate counterclockwise.
Checkpoint: Once the back is off, inspect the gasket. It should be a thin rubber ring seated in a channel on the case or the case back. If it is cracked, brittle, or flattened, order a replacement gasket before closing the watch. A damaged gasket is the single most common cause of water damage after a DIY battery change.
Branch point: If the gasket is damaged, stop the battery replacement here and order a new gasket before proceeding. Closing the watch with a compromised gasket means the watch may appear fine for weeks while moisture slowly works its way in—corrosion damage is often invisible until the movement stops entirely. A replacement gasket costs a few dollars; a movement service starts at $150.
Step 3: Locate and Remove the Old Battery
The battery sits under a metal retaining clip or a plastic holder. You will see the movement’s caliber number stamped on the bridge nearby—verify it matches your expectation before proceeding.
Use plastic tweezers or a toothpick to gently lift the retaining clip, then slide the battery out. Do not pry the battery straight up with force—some movements have a spring contact underneath that can bend. Note the orientation of the battery (which side faces up) before removing it. Most Tissot movements have the positive (+) side facing up, but not all.
Step 4: Install the New Battery
Place the new battery in the same orientation as the old one. Press it down gently until the retaining clip snaps back into place. The battery should sit flat and secure—if it rocks or shifts, the retaining clip is not properly engaged.
Checkpoint: Before closing the watch, confirm the battery is the correct code and voltage. A 377 cell (SR626SW) is 6.8mm in diameter and 2.6mm thick. A 371 cell (SR920SW) is 9.5mm in diameter and 2.1mm thick. If the new battery is visibly smaller or larger than the old one, stop—you have the wrong cell.
Step 5: Close the Case Back
For snap-off backs: Align the case back with the case, ensuring the gasket is seated in its channel. Press down firmly with your thumbs, working evenly around the perimeter until it clicks into place. If it does not seat, do not hammer it—remove it, check the gasket, and try again.
For screw-down backs: Clean the gasket channel, apply a thin film of silicone grease to the gasket (this helps it seal and prevents it from sticking), and place the back in position. Turn clockwise until snug. Do not overtighten—hand-tight plus a quarter turn is sufficient for most backs.
Step 6: Verify the Watch Runs
Pull the crown out to the time-setting position and set the correct time. Push the crown back in. The seconds hand should begin moving immediately. If it does not, the battery may not be seated properly, or the movement may have a more serious issue.
Common Mistakes and Where People Get Stuck
Using the wrong battery code. The most common error is assuming all Tissot watches take the same battery. They do not. The PRX quartz (F06.115) takes a 371; a vintage 1980s Tissot with a 955.412 takes a 377. Installing a 371 into a movement designed for a 377 can cause poor contact or damage the battery clip.
Slipping with a case knife. A slip with a case knife can scratch the case back, which is visible every time you wear the watch. It can also cut the gasket, compromising water resistance. If you feel the knife slipping, stop and reposition rather than forcing it.
Forgetting the gasket. Replacing the battery without checking the gasket is the fastest way to turn a ten-minute job into a costly repair. A gasket that has dried out or cracked will allow moisture into the case, which can corrode the movement. If the gasket looks questionable, replace it before closing the watch.
Overtightening the screw-down back. A screw-down back that is torqued too hard can strip the threads, which requires a machinist to repair. Hand-tight plus a quarter turn is the standard.
When to Stop and Call a Professional
A Tissot battery replacement is a legitimate DIY job for snap-off backs and lightly tightened screw-down backs. But there are clear stop points:
- The watch has a water resistance rating above 50 meters. The PRX quartz is rated to 100 meters. After opening it, the gasket must be replaced and the watch pressure-tested to restore that rating. A home reassembly without a pressure test means you no longer know the watch’s water resistance—it may be fine, or it may leak at 10 meters. If you swim or shower with the watch, this is not a risk worth taking.
- The movement shows signs of corrosion or battery leakage. White or green residue around the battery compartment indicates a leaked battery. This requires professional cleaning to prevent further damage.
- The watch does not run after the new battery is installed. If the movement does not start with a fresh, correctly sized battery, the problem is not the battery. A professional diagnosis is needed.
- You do not have the correct tools. Improvising with a knife or screwdriver is how case backs get scarred and movements get damaged. If you do not have the right tool, the $15–$45 cost of a professional battery change is cheaper than the repair bill for a damaged case.
The Success Check
You have successfully replaced the battery when:
1. The watch runs immediately after closing the case back.
2. The case back is seated evenly with no gaps or raised edges.
3. The gasket is intact and seated in its channel.
4. The watch keeps time within normal quartz accuracy (roughly ±15 seconds per month) over the next few days.
If any of these fail, reopen the watch and check the battery seating and gasket before considering a professional repair. A battery that is slightly off-center can prevent the retaining clip from engaging, which will cause intermittent power loss that looks like a dead battery.
Replacing a Tissot battery is a straightforward task for a careful owner with the right tools. The key is knowing your movement, using the correct battery, and respecting the gasket. Do those three things, and the job takes ten minutes. Skip any of them, and you may be looking at a service bill that dwarfs the cost of a professional battery change.
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.