391 / SR1120W battery equivalent

Also sold as SR1120W. 1.55 V with a flat discharge curve — the usual choice for quartz watches.

Chemistry

Silver oxide

Voltage

1.55 V

Size

11.6 × 2.1 mm

Inches

0.457 × 0.083 in

Drain

High drain (W)

Typical capacity

~45 mAh

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Equivalents by brand

Brand	Number
Renata	391
Energizer / Eveready	391
Maxell / Panasonic / Sony	SR1120W
Varta	V391
Rayovac	391
Duracell	D391
Bulova	609
Timex	L
Citizen	280-30
Seiko	SB-BS/ES
IEC	SR55
IEC size	SR1121

Also known as

SR1120WV391D391609L280-30SB-BS/ESSB-BSSB-ESSR55SR1121AG8

What it fits

Watches with extra features. Confirm the printed number or measure the old cell before you buy — a 0.5 mm height difference will not seat correctly.

IEC names encode chemistry and size. SR is silver oxide, LR is alkaline, and CR is 3 V lithium. The digits are diameter and height in tenths of a millimeter, so SR1120W is about 11.6 mm across and 2.1 mm thick.

Same size, different drain

These cells share the 11.6 × 2.1 mm can. Low-drain (SW) is for simple analog watches. High-drain (W) handles lights, alarms, and chronographs. A modern multi-drain cell can usually cover both.

Same size, different chemistry

These fit the same cavity but are not true equivalents. Voltage and discharge curve differ — do not use them as a silent swap in a quartz watch.

FAQ

What battery replaces a 391?

Any of these are common equivalents: 391, SR1120W, V391, D391, 609, L, 280-30, SB-BS/ES. They are 1.55 V silver oxide cells, 11.6 × 2.1 mm.

Is 391 the same as SR1120W?

Yes — SR1120W is the IEC / Japanese-brand name for the same 391 cell.

What devices use a 391?

Watches with extra features