From silver oxide to lithium: A complete guide to common and rare batteries for all types of quartz watches.

A Comprehensive Guide to Watch Batteries: Types, Markings, Proper Selection, and Safe Replacement

In the modern watch world, the battery is the beating heart of every quartz movement - whether it's an elegant Swiss watch, a highly durable Japanese one, or an everyday fashion watch. Incorrect battery selection, or a hasty replacement, can lead to inaccuracy, shortened movement life, and even damage to the water resistance. This guide professionally and accurately summarizes everything you need to know: battery types, deciphering numbers and codes, compatibility with watch types and brands, tips for safe replacement, and common pitfalls to avoid.

Quartz, Automatic, and Everything In Between - Why the Battery Matters?

A quartz watch operates by the oscillation of a quartz crystal powered by a constant voltage from the battery. The advantages: high accuracy, simple maintenance, and reasonable cost. An automatic/mechanical watch has no battery at all - the movement is mechanical and wound by hand movement or manual winding. Additionally, there are hybrid watches: solar (charged by light) and kinetic (charged by wrist movement), which use a dedicated rechargeable cell/capacitor instead of a disposable button battery. Therefore, for quartz watches, proper battery matching is essential for accuracy, durability, and longevity.

Main Chemistries in Watch Batteries (and what to choose)

1) Silver Oxide - IEC marking: SR

This is the primary standard for many analog and digital wristwatches. Nominal voltage ~1.55V, stable discharge curve (voltage remains almost constant until end of life), and good tolerance for low and continuous loads.
- You will usually see combinations like SR626SW, SR621SW, SR920SW, and so on.
- The suffix SW indicates Low Drain and is suitable for a simple "time-date" watch; the suffix W indicates High Drain and is suitable for watches with a chronograph, digital features, or illumination. Physically, the size is identical - the difference is in the chemistry/discharge control for different load environments.

2) Disposable Lithium - IEC marking: CR / BR (3V)

Mainly used in digital watches, certain smartwatches, or sports/rugged models, and sometimes in larger modules or with illumination/alarms. Common models: CR2016, CR2025, CR2032 (numbers encode diameter/thickness in mm). Lithium offers high energy density and very long shelf life. BR (Lithium Poly-Carbon Monofluoride) is rarer and chosen primarily for extreme temperature ranges - less common in watches.

3) Alkaline - IEC marking: LR

Available as "size-identical" alkaline batteries for SR batteries (e.g., LR626). In watches, alkaline is not recommended: the nominal voltage is lower (~1.5V) and the voltage drop over the battery's lifespan is sharp and unstable - this affects accuracy and sometimes shortens the movement's life. The rule: when there is SR - do not replace with LR.

4) Rechargeable Batteries for Solar/Kinetic Watches - Dedicated Cells

Solar watches (e.g., Citizen Eco-Drive) and kinetic watches (e.g., Seiko Kinetic) use dedicated rechargeable cells: a capacitor/rechargeable cell (Secondary Cell) with chemistry and voltage different from a regular button battery. These come under manufacturer codes (like CTL/MT from certain suppliers) and are not interchangeable with standard SR/CR. If you have such a watch - contact a watchmaker/service center with the exact manufacturer's part number.

Understanding the Numbers: 377 = SR626SW, 364 = SR621SW, and so on

Every watch battery has a "generic" IEC code (e.g., SR626SW) and often a short commercial number like 377. The numbers vary between manufacturers (Renata, Maxell, Energizer, Sony, etc.), but the IEC is uniform and represents the size and type. Some particularly common examples:

• 377 = SR626SW
• 376 = SR626W (same size, High Drain version)
• 364 = SR621SW
• 371 = SR920SW
• 395 = SR927SW
• 394 = SR936SW
• 392 = SR41SW
• 379 = SR521SW
• 373 = SR916SW
• 390 = SR1130SW
• 391 = SR1120SW
• 357 = SR44W / 303 = SR44SW (same size, different loads)

If "Battery 371" is indicated on the back cover/inside the movement - this is the most accurate guidance. When "SRxx...W/SW" appears - maintain the same suffix (W or SW) according to the watch's functions.

Compatibility by Watch Type and Brand - How to Approach it Correctly

Swiss Watches (Tissot, Longines, TAG Heuer, Omega, Certina, Rado, etc.)

Most quartz models will feature silver oxide batteries in common sizes such as 377, 371, 395, and 394. A common Swiss battery brand is Renata, but there is no "brand" requirement - the main thing is to choose the correct size/IEC and high quality.
The rule: simple "time-date" watch → usually SW (Low Drain). Chronograph/multiple functions → sometimes W (High Drain). When the caliber model number (ETA/Ronda, etc.) is known, you can verify the exact battery type on the manufacturer's website/technical catalog.

Japanese Watches (Seiko, Citizen, Casio)

• Analog Quartz: Similar to Swiss watches - common SRs (e.g., 364/377/371/395).
• Digital and Rugged Quartz (G-Shock, ProTrek): Often you will see CR lithium (like CR2016/2025/2032), especially in models with multiple screens and illumination.
• Solar/Kinetic: Dedicated charging units, not replaced with standard SR/CR.

Fashion Brands and House Brands

Most of them are based on Miyota (Japanese), Ronda (Swiss) movements or similar calibers - and therefore will also rely on SRs in common sizes (377/364/371/395). Always check: engraving on the back cover, movement specification sheet, or marking inside the cover.

How to Choose the Right Battery - A Short and Accurate Checklist

1. Check the official recommendation: The number (e.g., 371) is usually indicated on the back cover/in the caliber specifications.
2. Maintain the same IEC: If SR626SW is specified - it's 377, and if SR626W is specified - it's 376. Do not mix W and SW without reason.
3. Avoid Alkaline (LR) when an SR alternative of the same size exists.
4. Quality brand: Renata / Maxell / Sony / Energizer, etc. – maintain reliability and accuracy.
5. Expiration/Shelf life: Choose fresh packaging. Silver oxide batteries have good shelf life, and lithium are excellent - but fresh is still preferable.
6. Do not "invent": If there is no marking, identify by the caliber (movement number) and complete an accurate technical search or contact a watchmaker.

Safe Replacement - What to Do (and What Not to Do)

• Maintain water resistance: Opening the cover compromises water resistance. Professional replacement also includes replacing the gasket and, if necessary, performing a pressure test to maintain water resistance.
• Cleanliness and protection: Work on a clean surface, with non-conductive/plastic tweezers; avoid direct contact with battery terminals; do not drop particles into the movement.
• Static discharge: Beware of static electricity.
• Do not bend tabs: The tabs holding the battery are delicate; excessive bending will destroy the contacts.
• Check voltage: Before closing, check that the watch has "woken up" and the hands are moving; for a chronograph, reset functions according to manufacturer instructions.
• Solar/Kinetic: Do not insert a "regular button battery" instead of a rechargeable cell. This is a recipe for damage.

Common Mistakes - and How to Avoid Them

• Replacing SR with LR: Will impair accuracy and sometimes shorten the movement's life.
• Mismatch between W and SW: A chronograph may "drain" a Low-Drain battery very quickly; a simple watch does not "need" High-Drain.
• Compromised water resistance: Replacement without gasket inspection can lead to moisture and dust ingress - and expensive damage.
• Leakage: Batteries left in old devices may leak. In quality watches, this is rarer with quality SR - but don't gamble. Replace on time.
• Inserting the battery incorrectly: Sounds trivial, but it happens. The +/- marking must be clear.

How long does a battery last, and what affects it?

In simple analog quartz watches, a silver oxide battery will last one to three years on average. In chronographs, with frequent use of the stopwatch/illumination - less. In 3V lithium (CR) digital watches - sometimes more, but depends on functions (display, illumination, alarms). In solar watches - the rechargeable cell lasts for years, but requires maintenance (exposure to light) and documented replacement when capacity significantly decreases.

Recycling and Environmental Disposal

Button batteries should be disposed of for recycling. Even without mercury (as is common today), they are electronic waste. Many stores/labs have collection bins; do not throw them in regular trash.

Frequently Asked Questions

How do I know which battery is suitable for my watch?
Look for a marking on the back cover ("Battery 371", etc.), or the caliber number (e.g., Ronda/ETA/Miyota) and check the manufacturer's table. If none - contact a professional watchmaker.

Is every 377 identical? There's Renata 377, Maxell 377, etc...
Yes - 377 is the commercial name for the SR626SW size. Different brands, same IEC. Choose a quality and reliable manufacturer.

Can I use 376 instead of 377?
Physically identical, but 376 is the High-Drain version and 377 is Low-Drain. For a simple watch, SW is preferable; for a chronograph or high load, the manufacturer may recommend W. Follow the official marking.

Can I replace SR with LR to save money?
Technically, it sometimes "works," but it's not recommended: alkaline (LR) batteries are less stable, less accurate, and have a shorter battery life. For watches - choose SR.

The watchmaker offered to replace the gasket and perform a pressure test - is it mandatory?
If your watch is water resistant and you want to maintain it - yes. Professional replacement usually includes a water resistance test; this saves expensive damage over time.

My solar/kinetic watch stopped - should I put a regular button battery in it?
No. These are dedicated rechargeable cells/capacitors with different voltage/chemistry. Contact an authorized service center with the exact part number.

Why does the watch sometimes stop even after replacement?
The battery may not be seated correctly, contacts may be dirty/bent, or there may be a movement malfunction. Moisture that entered previously can also cause corrosion. In such a case - a lab.

A Final Tip: Accuracy, Reliability, and Peace of Mind

Choosing the right battery for a wristwatch is a combination of precise matching to size/IEC, maintaining W/SW as needed, using a quality brand, and professional replacement with proper sealing when it's a water-resistant watch. This is not the place for shortcuts - a suitable battery maintains accuracy, extends the life of the movement, and prevents unnecessary malfunctions.

Choosing the correct watch battery and ensuring a professional replacement process guarantees accuracy, durability, and peace of mind over time. However, not every problem is solved simply by replacing the battery - sometimes, a water resistance check, movement repair, or more thorough maintenance is also required. In such cases, it is advisable to consult experts with experience and knowledge in the field.

On our website, you can also find a professional watch laboratory, offering replacement, testing, and repair services - so your watch can function exactly as it was designed to.