Keep button-cell batteries away from children. If a battery may have been swallowed, go to A&E immediately. Do not wait for symptoms, give food or drink, or try to cause vomiting. NHS Great Ormond Street Hospital guidance checked 25 October 2026.
This is a preparation checklist, not a universal opening procedure. Watches differ, including in battery retention, electrical reset requirements and case sealing. Use the maker's instructions for the exact watch and movement.
First decide whether to proceed
| Situation | Next step |
|---|---|
| Valuable or sentimental watch | Use a professional |
| Water resistance matters | Arrange replacement with appropriate seal inspection and testing |
| Case method or cell reference is unknown | Identify it from maker documentation first |
| Leakage, corrosion or a damaged retainer | Stop and obtain service |
| Solar or rechargeable watch | Do not substitute an ordinary disposable cell |
Prepare the bench
Work away from children and pets. Keep new cells in secure packaging until needed, and have a secure container ready for the old cell. Photograph the watch before opening. Identify the correct case-back tool and confirm how the case will be closed.
Follow the exact movement instructions
Confirm the battery reference, chemistry and polarity from reliable documentation; appearance alone is insufficient. Follow the maker's instructions for releasing the retainer and handling the replacement. Avoid bridging contacts with metal tools. Do not lever against the coil or force a cell under a clip. Any uncertainty is a reason to stop.
After replacement, follow any maker-specified reset procedure. Check that the watch runs, but do not treat running as proof that the case is sealed. Opening a watch can void its warranty and its water resistance. Water-resistance testing needs proper equipment.
Finish safely
Account for both cells before leaving the bench. Secure the spent cell and take it to an appropriate battery collection point, following local instructions. Used cells still present an ingestion risk. Never leave them loose in a parts tray or household rubbish.
Sources & further reading
- NHS Great Ormond Street Hospital: button batteries · Checked 2026-10-25
- GOV.UK: using button and coin batteries · Checked 2026-10-25