Casio · Watches
Casio MRW-210H battery
1 × 1.55V silver oxide button cell
Casio Operation Guide 5458/5474 names Module 5474 — one SR927SW. Confirm module 5474 on the caseback (module 5458 uses SR621SW).
How to replace it
| Notes | Case-back service typically required; water resistance should be retested after opening. |
|---|---|
| Access | Professional recommended |
Important
- Module 5458 on the same PDF uses SR621SW — always verify the module on the caseback (MRW-210H maps to 5474).
- Prefer silver-oxide SR927SW / 395 over alkaline AG7 / LR57 for this movement.
Sources
Helpful for this device
Optional tools for opening, testing or charging — separate from the battery answer.
- Fluke 101 Digital Multimeter
Accurate open-circuit voltage and basic electrical checks
- Klein Tools MM400 Multimeter
General DC voltage checks including battery terminals
- Digital multimeter
Measure open-circuit voltage and general electronics checks
New battery but still not working?
A fresh 1 × SR927SW should restore Casio MRW-210H if the battery was the problem. Work through the checks below before replacing the device.
- Check the battery type
This device needs 1 × SR927SW (silver_oxide). Rechargeable cells are not supported for this device. Same size does not always mean the same battery.
- Check known model-specific issues
Module 5458 on the same PDF uses SR621SW — always verify the module on the caseback (MRW-210H maps to 5474). Prefer silver-oxide SR927SW / 395 over alkaline AG7 / LR57 for this movement.
- Confirm the battery itself
For most coin cells, fitting a known-good fresh cell of the correct code is simpler than capacity testing.
- Still not responding?
If a correct, fresh battery installed properly does not restore the device, the fault may be elsewhere — the device may need service or replacement.