Maxell SR927SW Silver Oxide Battery (395)

Maxell SR927SW is a 1.55V silver oxide button cell engineered for low‑drain devices that need steady voltage for precise operation—most commonly analog watches, small calculators, and measuring instruments. It matches the watch code “395.”

At a Glance

• Chemistry: Silver Oxide (low drain)
• Nominal voltage: 1.55V
• Typical capacity: ~55 mAh
• Size: 9.5 mm diameter x 2.7 mm height (IEC: SR927)
• Operating range (typical): -10°C to +60°C

When to Choose SR927SW

• Use for analog watches without power‑hungry features (no frequent alarms, strong backlights, or motors).
• Suitable for low, steady current devices: small calculators, timers, and metering tools.
• If your device specifies “SR927SW” or “395,” this is the correct fit.

Alternatives and Compatibility

• High‑drain version: SR927W (often labeled “399”) is better for devices with alarms or lights. Some brands sell multi‑drain 395/399 cells that cover both cases—check your device manual.
• Alkaline LR927/AG7 fits physically but has lower capacity and a less stable voltage curve; not recommended except as a short‑term emergency substitute.
• CR927 is a 3V lithium coin cell with the same size but double the voltage; do not substitute unless the device specifically requires CR927.

Expected Service Life

Analog watches typically draw ~1–3 µA. With ~55 mAh capacity, you can expect roughly 2–4 years of service in most watches (actual life depends on movement design, complications, and ambient temperature). Calculators and meters vary by usage and duty cycle.

How to Replace Safely

1. Open the case with the proper tool; protect gaskets to preserve water resistance.
2. Note polarity before removal. The “+” side usually faces up.
3. Handle the new cell with plastic tweezers or gloves to avoid skin oils on contacts.
4. Seat the battery firmly, reassemble, and verify operation.

Tip: If a watch stops soon after replacement, check for a displaced insulator, dirty contacts, or a pinched gasket. When in doubt, visit a watch technician.

Storage and Safety

• Store in original packaging in a cool, dry place; avoid heat and humidity.
• Keep away from metal objects to prevent short circuits.
• Button batteries are hazardous if swallowed. Keep out of reach of children; if ingested, seek immediate medical attention.
• Recycle used cells at a battery collection point; do not dispose of in household trash.

Common Cross‑References

• Watch code: 395 (low‑drain)
• IEC: SR927SW (size 927, 2.7 mm height)
• Related: 399 (SR927W, high‑drain), LR927/AG7 (alkaline, not recommended as a direct replacement), CR927 (3V lithium, not interchangeable)

Size and Type Comparison

Type	Voltage	Size (mm)	Typical Capacity	Use Case
SR927SW (395)	1.55V	9.5 x 2.7	~55 mAh	Low‑drain devices (analog watches)
SR927W (399)	1.55V	9.5 x 2.7	~50–55 mAh	High‑drain features (alarms, lights)
LR927 / AG7	1.5V	9.5 x 2.7	Lower than silver oxide	Emergency substitute only
CR927	3V	9.5 x 2.7	Varies by brand	Only for devices designed for 3V lithium

FAQ

Is SR927SW the same as 395?

Yes. “395” is the common watch code for SR927SW (low‑drain, 1.55V silver oxide).

Can I use 399 instead of 395?

Often yes. 399 (SR927W) is the high‑drain version. Many devices accept it, and some brands sell multi‑drain 395/399 cells. Check your device manual to be sure.

Why avoid LR927 and CR927?

LR927 (alkaline) has lower capacity and less stable voltage; CR927 is 3V lithium and not voltage‑compatible with most 1.55V silver oxide devices.

What is the shelf life?

Typically 3–5 years when stored unopened in a cool, dry place. Always check the expiration date on the packaging.