309 / SR754SW battery equivalent

Also sold as SR754SW. 1.55 V with a flat discharge curve — the usual choice for quartz watches.

Chemistry

Silver oxide

Voltage

1.55 V

Size

7.9 × 5.4 mm

Inches

0.311 × 0.213 in

Drain

Low drain (SW)

Typical capacity

~70 mAh

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Equivalents by brand

Brand	Number
Renata	309
Energizer / Eveready	309
Maxell / Panasonic / Sony	SR754SW
Varta	V309
Rayovac	309
Duracell	D309
Bulova	70T
IEC	SR48
IEC size	SR754

Also known as

SR754SWV309D30970TSR48SR754SG5

What it fits

Compact watches and specialty instruments. 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 SR754SW is about 7.9 mm across and 5.4 mm thick.

Same size, different drain

These cells share the 7.9 × 5.4 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.

FAQ

What battery replaces a 309?

Any of these are common equivalents: 309, SR754SW, V309, D309, 70T, SR48, SR754, SG5. They are 1.55 V silver oxide cells, 7.9 × 5.4 mm.

Is 309 the same as SR754SW?

Yes — SR754SW is the IEC / Japanese-brand name for the same 309 cell.

What devices use a 309?

Compact watches and specialty instruments