Kidde · Smoke & CO alarms
Kidde 20SDR battery
2 × 1.5V alkaline cell
How to replace it
| How to open | Open the battery compartment. Install two AA alkaline cells matching polarity. Close and test. |
|---|---|
| Orientation | Match +/− |
| Low battery indicator | Low-battery alert (beep / voice on some DETECT models) |
| Notes | Kidde 20SDR product page: 2 AA replaceable batteries. Related 20SDR-VRF support specifies alkaline Energizer E91 / Gold Peak 15A / Golden Power GLR6A and states lithium batteries should not be used. |
| Access | Tool-free |
Important
- Not a 9V alarm — uses 2× AA alkaline.
- Do not use lithium AA unless your exact unit’s manual allows it; DETECT AA family guidance for related SKUs rejects lithium.
Sources
Helpful for this device
Optional tools for opening, testing or charging — separate from the battery answer.
- Ansmann Energy Check LCD
Quick household cell check (good / low / replace)
- ZTS Mini-MBT Multi-Battery Tester
More informative state-of-charge style checks across common formats
- Battery tester
Quick good / low / dead check for household cells
New battery but still not working?
A fresh 2 × AA should restore Kidde 20SDR if the battery was the problem. Work through the checks below before replacing the device.
- Check orientation
Confirm the cell is seated correctly: Match +/−
- Check the battery type
This device needs 2 × AA (alkaline). Rechargeable cells are not supported for this device. Same size does not always mean the same battery.
- Check known model-specific issues
Not a 9V alarm — uses 2× AA alkaline. Do not use lithium AA unless your exact unit’s manual allows it; DETECT AA family guidance for related SKUs rejects lithium.
- Confirm the battery itself
If you have a battery tester or multimeter, check the cell. A low open-circuit voltage often means replace; for rechargeable AA/AAA, a capacity test is more informative than voltage alone.
- 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.
Need to replace the device?
Kidde 20SDR is still sold new. Only buy another if a fresh battery and the checks above did not help.