Renata 370 (SR920W)

Overview

The Renata 370 (SR920W) is a high-drain silver-oxide button cell designed for analog watches that draw intermittent bursts of current, such as models with chronographs, alarms, or backlights. It delivers a stable 1.55 V output for precise timekeeping and reliable function under load.

Key Specs

Chemistry	Silver-oxide (mercury-free)
Nominal voltage	1.55 V
Size	9.5 × 2.1 mm (SR920 form factor)
Drain type	High-drain (W)
Typical capacity	~35–45 mAh (varies by brand/load)
Operating temp	Approx. -10 to +60 °C
Compliance	RoHS; mercury-free
Equivalent codes	SR920W, 370, D370 (Duracell), V370 (Varta), 370 (Energizer/Murata/Maxell/Panasonic)

When to Choose the 370 (SR920W)

• Use if your watch/manual or caseback specifically lists SR920W or 370.
• Best for watches with chronograph, alarm, or light features that need higher pulse current.
• Avoid if the watch specifies SR920SW or 371 (low-drain); use 371 instead.
• If you cannot confirm W vs. SW, choose a reputable multi-drain (370/371) cell or consult the movement manual.

Performance and Expected Life

• Voltage stability: Flat 1.55 V discharge curve supports accurate timekeeping.
• Service life (typical):
  • Chronograph watch used regularly: about 12–24 months.
  • Frequent alarm/light use: roughly 6–18 months.
  • Time-only movement that specifies W: up to 2–3 years.

  Actual life varies with feature use, movement efficiency, and temperature.

• Shelf life: Low self-discharge; store cool and dry for multi‑year readiness.

Compatibility Notes

• Same size, different drain: 371 (SR920SW) shares dimensions but is low-drain. Match what the watch calls for.
• Cross-reference: Look for SR920W or 370 on the old battery, inside the caseback, or in the movement manual.
• Mixing types: Do not replace a specified SW with W (or vice versa) unless the manufacturer allows it or you use a certified multi-drain cell.

Installation Tips

1. Confirm the required code (SR920W/370) before opening the case.
2. Work on a clean, static-free surface; use non-metal tweezers and avoid touching battery faces.
3. Insert with correct polarity (+ usually facing up); verify the retaining clip is seated.
4. Inspect and replace case gaskets if worn; pressure-test water‑resistant watches after replacement.
5. Clean contacts lightly with 90%+ isopropyl alcohol if corroded; allow to dry fully before assembly.

Storage and Safety

• Store in original packaging, 10–25 °C, low humidity; keep away from metal objects.
• Do not recharge, short-circuit, puncture, or expose to high heat.
• Keep out of reach of children. If swallowed, seek immediate medical attention.
• Recycle through local battery collection programs; do not dispose of in household trash.

FAQ

Is 370 the same as SR920W?

Yes. 370 is the common model number for the IEC size SR920W (high-drain) silver-oxide cell.

What’s the difference between 370 and 371?

Both are 9.5 × 2.1 mm silver-oxide cells. 370 (SR920W) is high-drain for functions like chronographs/lights; 371 (SR920SW) is low-drain for time-only movements.

Can I use a 370 instead of a 371?

Follow the watch specification. If the movement requires 371 (SW), use 371 or a certified multi-drain cell. Using the wrong drain type can reduce accuracy or life.

What are the common cross references for 370?

SR920W, 370, D370 (Duracell), V370 (Varta), and brand-labeled 370 from Energizer, Murata (Sony), Maxell, and Panasonic.

How long will a 370 last in my watch?

Typically 1–2 years in a chronograph, shorter with frequent light/alarm use, and up to ~3 years in time-only movements that call for W. Actual life varies by usage and movement.