Ring · Smart home sensors
Ring Alarm Contact Sensor (2nd Gen) battery
2 × 3V lithium coin cell
Ring Alarm Contact Sensor (2nd Gen) uses 2× CR2032. Replace both cells together and keep coin cells away from children. Do not buy CR123A from a 1st Gen guide.
How to replace it
| How to open | Disarm Alarm. Slide sensor off mounting bracket. Replace both CR2032 cells. Slide back onto bracket until it clicks. |
|---|---|
| Orientation | Match +/- symbols |
| Low battery indicator | Low battery warning in Ring app |
| Notes | Replace both coin cells together. |
| Access | Tool-free |
Important
- Generation: 2nd Gen uses 2× CR2032 — not the same as 1st Gen 1× CR123A.
- Keep coin cells away from children (ingestion hazard).
Sources
Helpful for this device
Optional tools for opening, testing or charging — separate from the battery answer.
- Coin cell / button cell battery tester
Quick check of CR / LR / SR button and coin cells before fitting
- Fluke 101 Digital Multimeter
Accurate open-circuit voltage and basic electrical checks
- Digital multimeter
Measure open-circuit voltage and general electronics checks
New battery but still not working?
A fresh 2 × CR2032 should restore Ring Alarm Contact Sensor (2nd Gen) if the battery was the problem. Work through the checks below before replacing the device.
- Check orientation
Confirm the cell is seated correctly: Match +/- symbols
- Check the battery type
This device needs 2 × CR2032 (lithium). Rechargeable cells are not supported for this device. Same size does not always mean the same battery.
- Check known model-specific issues
Generation: 2nd Gen uses 2× CR2032 — not the same as 1st Gen 1× CR123A. Keep coin cells away from children (ingestion hazard).
- 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.