Maxell SR626SW (377) Silver Oxide Watch Battery

The Maxell SR626SW is a low‑drain, 1.55 V silver‑oxide button cell sized 6.8 × 2.6 mm. It delivers a flat discharge curve for accurate timekeeping and steady performance in compact electronics that specify 377/SR626SW.

At a glance

Chemistry	Silver oxide (low‑drain, SW)
Nominal voltage	1.55 V
Size	6.8 mm (diameter) × 2.6 mm (height)
Typical capacity	26–30 mAh (varies by device load and conditions)
Operating temp.	Approx. −10 °C to +60 °C
Common codes	377, SR626SW, SR66, SR626

When to choose this battery

• Use if your device or old battery is marked 377, SR626SW, SR66, or SR626.
• Best for analog watches, simple calculators, and precision measuring tools (e.g., calipers, micrometers) that draw low, steady current.

When to avoid or pick an alternative

• If your watch/manual calls for SR626W (high‑drain), choose that instead—digital watches with alarms, lights, or step counters may need the W type.
• Avoid alkaline look‑alikes (LR626, AG4, 377A): lower capacity and sloping voltage can shorten runtime and affect accuracy.

Compatibility and cross‑reference

The following designations commonly refer to the same silver‑oxide size:

• IEC/JIS: SR626SW
• Industry/retail: 377, SR66, SR626
• Typical brand equivalents: Renata 377, Energizer 377/376, Panasonic SR626SW, Sony 377, Varta/V377

Note: LR626 / AG4 are alkaline equivalents in the same size but are not recommended for precision devices.

Performance expectations

• Analog watch: often 2–3 years, depending on movement, features, and ambient temperature.
• Calculator/measuring tools: months to years based on usage and auto‑off behavior.
• Voltage behavior: flat 1.55 V profile helps maintain timekeeping accuracy until near end of life.

Installation guide

1. Verify the required code (377/SR626SW) on the old cell or in the manual.
2. Open the battery compartment carefully; for watches, protect gaskets to maintain water resistance.
3. Note polarity before removal. The + side usually faces up.
4. Insert the new battery with clean, dry hands or plastic tweezers; avoid touching both faces.
5. Secure the cover and confirm operation (timekeeping, display, or device startup).

Storage and handling

• Store in original packaging in a cool, dry place (roughly 50–77 °F / 10–25 °C), away from humidity and direct sun.
• Do not carry loose cells with metal objects (risk of short circuit).
• Install before the date printed on the pack for best shelf performance.

Safety and disposal

• Button battery hazard: Keep away from children. If swallowed or inserted, seek immediate medical attention—do not wait for symptoms.
• Tape the terminals of spent cells before recycling to prevent shorting.
• Recycle at approved collection points; do not dispose of in household trash.

Pros and cons

• Pros: Stable 1.55 V output, good capacity for size, long shelf life, size compatibility with widely used 377 standard.
• Cons: Not ideal for high‑drain digital features (choose SR626W); more expensive than alkaline look‑alikes.

FAQ

What’s the difference between SR626SW and SR626W?

Both share the same size, but SW is tuned for low‑drain loads (analog watches). W is for high‑drain applications (digital functions, alarms, lights). Use the type specified by the device.

Can I use an alkaline LR626 instead of SR626SW?

It will fit, but it’s not recommended. Alkaline cells have lower capacity and a sloping discharge curve, often causing shorter runtime and potential accuracy issues.

Is 377 the same as SR626SW?

Yes. 377 is the common retail code for the SR626SW silver‑oxide cell.

How long will this battery last in my watch?

Many analog watches see roughly 2–3 years, but actual life depends on the movement, complications (e.g., date), and temperature.

How do I know the polarity during installation?

The positive face is the flat side typically marked with the code (e.g., 377/SR626SW). Match the polarity markings inside the device.