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Silver-oxide watch (SR)

SR616SW battery: equivalents & specs

The SR616SW, retail code 321, is a thin 1.55 volt silver-oxide watch battery, 6.8 mm across and 1.65 mm tall, with roughly 14 mAh of capacity. It is the slim member of the 6.8 mm family that also includes the common 364 and 377.

SR616SW battery drawing: 6.8 mm across, 1.65 mm thick SR616SW 1.55V + ⌀ 6.8 mm 1.65 mm
SR616SW, face and side profile, drawn to scale: 6.8 mm across, 1.65 mm thick.
Voltage
1.55 V
Size (D×H)
6.8 × 1.65 mm
Chemistry
Silver oxide (Ag2O)
Capacity
13-15 mAh

Same battery, other names

Every code below is the exact same cell as SR616SW. Any of them will fit and work identically.

321

Buying and replacement notes

Watch buyers regularly confuse the 321 with the 364 and 377 because all three are 6.8 mm across. Heights run 1.65, 2.1 and 2.6 mm respectively, and only the correct one both fits under the case back and maintains contact. The 321 suits slim dress movements; if your old cell reads 321, do not accept a 364 as a substitute.

Commonly used in

slim watchesthin quartz movements

Need a replacement?

Shop SR616SW batteries on Amazon →

⚠️ Keep away from children. Swallowed button batteries, especially 20 mm lithium coins, cause severe injury within hours. If a child swallows one, call the 24/7 National Battery Ingestion Hotline (US) at 800-498-8666 or poison control at 800-222-1222 immediately. What every parent should know.

Frequently asked questions

Are the 321 and 364 interchangeable?
No. Both are 6.8 mm wide silver-oxide cells, but the 321 (SR616SW) is 1.65 mm tall while the 364 (SR621SW) is 2.1 mm. The taller cell prevents the case back from seating, and the shorter one loses contact. Match the exact code.
What does SR616SW mean?
The IEC code encodes the cell: S for silver oxide, R for round, 616 for 6.8 mm diameter and 1.6 mm height, and SW for the low-drain electrolyte type used in simple analog watches. The retail number for this cell is 321.
How long does a 321 battery last in a watch?
Expect roughly two years in a slim analog movement. Capacity is modest at about 14 mAh, but low-drain watch movements sip current in microamps. A sudden stop rather than gradual slowing is normal for silver oxide when the cell is finally spent.

More Silver-oxide watch (SR) cells

SR416SWSR512SWSR516SWSR521SWSR527SWSR621SWSR626SWSR716SWSR721SWSR726SW