Tissot PRX Automatic 40mm Battery? None — It's Mechanical
The Tissot PRX Automatic 40mm is powered by the natural motion of your wrist — there is no battery inside, and no battery replacement is ever needed. It runs on the Powermatic 80 (ETA C07.111 base) caliber.
Important: The PRX Automatic is a mechanical watch — it does NOT use a battery. Do not confuse with the quartz PRX 40mm which uses SR920SW / 371.
Why does the Tissot PRX Automatic 40mm not need a battery?
Does the Tissot PRX Automatic 40mm need a battery?
No. It is a mechanical automatic watch — the mainspring is wound by an internal rotor that swings with the motion of your wrist. There is no battery inside.
Why does my Tissot PRX Automatic 40mm stop when I don't wear it?
Automatic watches store roughly 24–48 hours of power in the mainspring. If you leave it unworn beyond that window the watch will stop. Wind the crown or wear it and it will restart immediately.
How do I restart my Tissot PRX Automatic 40mm?
Shake it gently for 20–30 seconds, or manually wind the crown 20–30 times. Then set the time.
How often should I service it?
A full service by a qualified watchmaker every 3–5 years keeps the lubricants, mainspring and gaskets in good condition. No battery is ever replaced.
How to keep the Tissot PRX Automatic 40mm running
- Wear the watch daily or wind the crown 20–30 turns to keep it running
- If it stops, shake gently for 20–30 seconds or manually wind
- Full service (not battery) recommended every 3–5 years by a qualified watchmaker
- Never open the case back — automatic movements are sensitive to dust and shock
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Battery information is based on manufacturer documentation where available and community-verified sources. If you notice an error or have official documentation for this model, please contact us to help improve this database.