Renata 394 (SR936SW) Silver‑Oxide Watch Battery

The Renata 394 is a low‑drain, mercury‑free silver‑oxide button cell for larger analog watches and compatible electronics that call for SR936SW or 394. It provides a stable 1.55 V output and reliable runtime in low‑to‑moderate current draw applications.

Key specs

• Chemistry: Silver‑oxide (mercury‑free)
• Nominal voltage: 1.55 V
• Size: 9.5 mm diameter × 3.6 mm height (SR936 format)
• Drain type: Low‑drain (SW) for analog/quartz movements
• Compliance: RoHS; mercury‑free construction

When to choose it

• Use if your device or manual specifies SR936SW or 394.
• Best for analog quartz watches (time/date) and low‑drain timers or instruments.
• Good replacement when upgrading from alkaline LR936/AG9 for longer life and steadier voltage.

Avoid if

• Your device specifies SR936W (high‑drain) or has power‑hungry features (e.g., continuous alarms, bright LEDs, intensive chronograph functions). In that case, choose a high‑drain SR936W from the same size class.

Compatibility and part numbers

Common cross‑references for this size include: SR936SW, 394, D394, V394, SB‑A4. Always match the “SW” (low‑drain) marking if your device requires it.

Expected runtime

• Analog watch (time only): typically 2–4 years.
• Analog watch with date or light complications: typically 1.5–3 years.
• Actual life varies with movement efficiency, ambient temperature, and feature use.

Installation and care

1. Confirm the required code: SR936SW/394. Do not substitute high‑drain (W) unless specified.
2. Open the case carefully; protect gaskets and water‑resistance seals.
3. Handle the new cell with non‑metal tweezers or gloves; avoid touching the faces.
4. Match polarity: the flat side is typically positive (+).
5. Seat the cell firmly; check that clamps/springs are aligned.
6. After closing, verify timekeeping and, if applicable, have water‑resistance tested.

Storage and shelf life

Keep in original packaging until use. Store at room temperature, dry place (approx. 10–25°C). Typical shelf life up to 5 years with minimal self‑discharge.

Alternatives

• High‑drain variant: SR936W (same size; for devices that specify W/high‑drain).
• Alkaline LR936/AG9: budget option with shorter life and less stable voltage; not recommended for precision timekeeping.
• Do not use lithium or rechargeable cells unless explicitly specified by the device.

Safety and disposal

• Button cells are a choking and ingestion hazard. Keep away from children and pets.
• If swallowed, seek immediate medical attention or contact Poison Control.
• Do not recharge, short‑circuit, or expose to heat.
• Recycle or dispose of according to local battery recycling guidelines.

FAQ

Is 394 the same as SR936SW?

Yes. 394 is the industry number commonly used for the SR936SW low‑drain silver‑oxide size.

Can I use a 394 (SW) where SR936W is specified?

No. Devices that specify SR936W (high‑drain) may need higher pulse current. Use a high‑drain SR936W instead.

Can I replace an alkaline LR936/AG9 with a 394?

Yes, if the device fits SR936 size. Silver‑oxide 394 typically provides longer runtime and steadier voltage than LR936 alkaline.

Why did my new battery drain quickly?

Common causes include using a low‑drain (SW) in a high‑drain device, worn watch movement, moisture ingress, or a poor case seal increasing load. Confirm the correct type and have the device serviced if needed.