Ring · Smart home sensors
Ring Alarm Contact Sensor (1st Gen) battery
1 × 3V lithium cell
Ring Alarm Contact Sensor (1st Gen) takes 1× CR123A per Ring replacement guide, product specs, and install docs (OEM audit 2026-10-09). Disarm Ring Alarm before opening the cover. 2nd Gen uses 2× CR2032 — confirm generation on the device or in the Ring app before buying.
How to replace it
| How to open | Disarm Alarm. Press cover release button and lift battery cover. Replace CR123A matching +/-. Replace cover securely. |
|---|---|
| Orientation | Match +/- symbols on battery and compartment |
| Low battery indicator | Low battery warning in Ring app |
| Notes | Do not confuse with 2nd Gen (2× CR2032). |
| Access | Tool-free |
Important
- Generation: 1st Gen uses 1× CR123A — not the same as 2nd Gen 2× CR2032.
- OEM audit 2026-10-09: Ring replacement guide, US Contact Sensor (1st Gen) product specs, and install article all specify 1× CR123A. Pages attributing 2× CR2032 to 1st Gen are Gen2 conflation / stale copy — BBD keeps CR123A.
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 × CR123A should restore Ring Alarm Contact Sensor (1st 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 on battery and compartment
- Check the contacts
OEM audit 2026-10-09: Ring replacement guide, US Contact Sensor (1st Gen) product specs, and install article all specify 1× CR123A. Pages attributing 2× CR2032 to 1st Gen are Gen2 conflation / stale copy — BBD keeps CR123A.
- Check the battery type
This device needs 1 × CR123A (lithium). Rechargeable cells are not supported for this device. Same size does not always mean the same battery.
- Check known model-specific issues
Generation: 1st Gen uses 1× CR123A — not the same as 2nd Gen 2× CR2032.
- 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.
Current model
If this model is finished, the Manufacturer successor model is Ring Alarm Contact Sensor (2nd Gen).