In these alarm systems, a door or window sensor takes a CR2032 coin battery or a CR123A, and some motion detectors take 2 AA. The battery can change between generations of the same sensor.
Which sensor?
The battery it takes
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Sensor batteries by model
| Sensor | Battery | Battery life, maker’s figure |
|---|---|---|
| SimpliSafe Entry Sensor | One CR2032 | Up to 5 years |
| SimpliSafe Motion Sensor Gen 2 | One CR123A | Up to 4 years |
| SimpliSafe Motion Sensor Gen 1 | One CR123A | Up to 5 years |
| Ring Alarm Contact Sensor (2nd Gen) | Two CR2032 | Up to 3 years |
| Ring Alarm Contact Sensor (1st Gen) | One CR123A | Up to 3 years |
| Ring Outdoor Contact Sensor | Two AA | Not listed |
| Ring Alarm Motion Detector (2nd Gen) | Two AA | Not listed |
| Ring Alarm Motion Detector (1st Gen) | One CR123A | Not listed |
| ADT Command Door/Window Sensor (SiXCTA) | One CR123A | Not listed |
From SimpliSafe support, Ring Help and the ADT Support Center.
Before you open a sensor
Ring says to disarm Ring Alarm first, then slide the sensor off its mounting bracket. It warns that a battery put in the wrong way round could damage the device, so match the plus and minus symbols.
If a SimpliSafe sensor doesn’t come back online after a battery change, SimpliSafe says it may have been offline for too long.
Keep coin batteries away from children
The National Capital Poison Center says that if anyone swallows a battery, immediately call the 24-hour National Battery Ingestion Hotline at 1-800-498-8666 or your poison center at 1-800-222-1222. Don’t delay. Immediate treatment decreases severity.