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Home › Batteries › 329
Watch battery

329 is the same as SR731SW

1What it is2Safety3Other names4Facts5Buy it
  1. 1

    What it is

    SR731SW+ 1.55V

    329 is just another name for SR731SW. Same battery, different label, so you can buy either one.

    Search Amazon for 329As an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

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  2. 2

    Safety first

    Keep away from children and pets

    A swallowed coin or button battery can cause serious burns inside the body within 2 hours. If you think one was swallowed, get emergency help right away.

    Swallowed one? What to do now →
  3. 3

    Names you might see in the store

    All of these are the same battery. Any of them will work.

    SR731SW
  4. 4

    Quick facts

    Size
    About as wide as a pea
    Thickness
    As thick as 4 credit cards stacked
    Power
    1.55 volts
    Keeps in a drawer for
    About 5 years
    Rechargeable?
    No, use once
    Found in things like
    Analog watches
  5. 5

    Where to buy it

    As an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

    Amazon searchEnergizer listings, any pack sizeSearch Amazon for Energizer 329
    See results on Amazon →
    Amazon searchMulti-packs from any brandSearch Amazon for 329 (SR731SW) multi-packs
    See results on Amazon →
    Amazon searchDuracell listings, the same batterySearch Amazon for Duracell SR731SW
    See results on Amazon →

    Buttons open amazon.com 🇺🇸, picked from your country.

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See it at real size

SR731SW next to a US quarter and an AA battery. “Real size” matches your hand once your screen is set up in Measure it.

SR731SWThickness 3.1US quarterAA

What do the letters mean?

Battery names are a code. Here’s how to read 329:

3Watch-industry 300 series (Renata/Energizer numbering)
29Size and drain code. Maps to SR731SW, 7.9 × 3.1 mm

The same battery from each brand

BrandTheir name for it
Official nameSR731SW
Energizer329
Murata (formerly Sony)SR731SW
Renata (Swiss)329
MaxellSR731SW

Exact measurements

Width
7.9 mm (0.311 in)
Thickness
3.1 mm
Voltage
1.55V (empty at 1.2V)
Energy stored
37 mAh
Weight
—
Made with
Silver oxide
Works between
-10 … 60 °C
Official code
SR731SW

Questions people ask

Is 329 the same as SR731SW?

Yes. They’re the same battery with different names. You might also see SR731SW.

How long will a spare keep in a drawer?

About 5 years if it stays cool and dry.

Can I recharge it?

No. Never try to recharge it.

Which way up does it go?

Usually with the side marked “+” facing you or facing up. Look at how the old one sits before you take it out.

SR731SW+ 1.55V
SR731SWWatch battery
Search Amazon for 329As an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

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1What it is2Safety3Other names4Facts5Buy it