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1.55 V silver oxide

SR621SW / 364 battery equivalent

BuySR621SWSilver oxide · 1.55 V · 6.8 × 2.1 mm

Safe swap, same cell: 364 · V364 · D364 · 280-34 · SB-AG/DG · SR621 · SR60 · 1175SO

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Also printed as: 364

SR621SW: drawing from the dataset, diameter 6.8 mm, height 2.1 mmØ 6.8 mm2.1 mmTOPSIDE
Fig. 1 — SR621SW. Outline only. Both views share one scale. The terminal step, seal and markings are not drawn.

1.55 V · 6.8 × 2.1 mm · Silver oxide, low drain (Renata scope chart)

364 is the low-drain 6.8 × 2.1 mm silver-oxide cell, Renata code SR621SW, 19 mAh on the scope chart. Energizer's 364 sheet prints ANSI/NEDA-1175SO, IEC-SR60, 1.55 V, 20 mAh to 1.3 V. There is no separate high-drain twin in Renata's chart at this height.

Ratings from the cited sheets
ChemistrySilver oxide, low drain (Renata scope chart)
Nominal voltage1.55 V
Diameter × height6.8 × 2.1 mm
Renata scope chart, millimetres
Designation on the datasheetANSI / NEDA-1175SO, IEC-SR60
Drain classlow drain, as printed by Renata
WeightEnergizer 0.31 grams (0.11 oz.)

Size check at real size

Lay the old cell on the outline. This shows the top outline (diameter) and the side outline (height) at 1:1 once the screen is calibrated.

Capacity

These are not one test repeated. Capacity varies by brand, load, temperature and cutoff.

SourcemAhTest as printed
Renata19Capacity column of the July 2016 scope chart. The chart does not print the load or cutoff for this row.
Energizer20to 1.3 volts; rated at 68k ohms continuous at 21ºC

Cross-reference

Each code is printed on the cited chart. A shared outline is not, by itself, the same cell. Renata's chart puts Maxell, Panasonic, Sony and Toshiba in one column, so those four names share the code shown.

Where it is printedCode
Energizer364
Maxell, Panasonic, Sony, ToshibaSR621SW
VartaV364
Rayovac364
DuracellD364
TimexT
Citizen280-34
SeikoSB-AG/DG
IEC code on the Renata chartSR621 Printed as 'SR621 (SR60)'.
IEC code on the Renata chartSR60 Printed as 'SR621 (SR60)'.

Devices named on the Energizer guide

Watches. See watches.

Silver oxide watch and instrument cells

These are zinc/silver oxide button cells. Energizer's product sheets print a nominal 1.55 V. The silver-oxide application manual puts the open-circuit voltage at 1.6 V and the operating voltage, at ordinary drains, at 1.55 V or higher. The curve stays flat for most of the discharge. That is why a watch, a glucose meter, or a caliper that was specified for silver oxide keeps time or stays in calibration longer than it does on an alkaline cell of the same outline.

Renata splits each common outline into a low-drain cell and a high-drain cell. The low-drain code ends in SW (SR626SW is Renata and the trade number 377). The high-drain code ends in W (SR626W is 376). Energizer's manual explains the underlying choice without using those suffixes: a potassium hydroxide electrolyte carries a heavier current than a sodium hydroxide electrolyte, and the sodium hydroxide cells are the easier ones to seal. The manual does not print 'SW means NaOH'. This index does not add that sentence. It follows Renata's low-drain and high-drain labels, which are printed in the scope chart.

The two drains fit the same well. Energizer's cross-reference often puts the pair on one line (377/376, 357/303, 371/370) under 'replaces batteries labeled as'. Read that as a fit list. If the old cell or the watch case says 377 or SW, buy the low-drain cell. If it says 376 or W, buy the high-drain cell.

Energizer still prints the older short IEC codes on the datasheet: SR66 for the 6.8 × 2.6 mm cell, SR44 for the 11.6 × 5.4 mm cell, and so on. Renata prints the longer code, SR626SW or SR44W. Both appear on the page. The short code is shared by the low-drain and high-drain twins, so 'SR44' alone is not enough to pick 357 or 303. The suffix, or the three-digit number, is.

Sources

Last verified 2026-10-29.