How to choose the right watch battery
Silver oxide vs alkaline vs lithium — a practical guide to picking the correct battery for your quartz watch.
Why the chemistry matters
Most quartz watches ship with silver-oxide (SR) cells at 1.55 V. They hold voltage flat almost to the end, which keeps the second hand sweeping in regular steps until the battery actually dies.
Alkaline equivalents (LR) deliver 1.50 V and slope down over time. They are slightly cheaper but the watch may run a few seconds slower per month near end-of-life.
Lithium CR cells are 3.0 V and used in modules with backlight, alarm, or memory (digital chronographs, dive computers). Don't drop a CR into an SR slot — the voltage is double and you'll fry the movement.
Low-drain (SW) vs high-drain (W)
- SW ("low drain") — analog watches, no backlight. Examples: SR626SW (377), SR920SW (371).
- W ("high drain") — illumination, alarm, chronograph stepper motors. Examples: SR927W (399), SR1130W (389).
A low-drain cell in a high-drain watch will work but die fast. A high-drain cell in a normal analog watch is just more expensive for no benefit.
How to read the markings
A code like 377 / SR626SW tells you:
- 6 → diameter in mm → 6.8 mm
- 26 → height × 10 → 2.6 mm
- SW → low drain, silver oxide
So you can almost always cross-reference by physical size if the printed code is rubbed off.
Buying tips
- Check the expiry date on the package — silver-oxide cells slowly self-discharge.
- Prefer Renata, Sony/Murata, Maxell, Energizer for Swiss and Japanese movements.
- Avoid no-name "377" cells from marketplaces — they're often re-labelled alkaline.