If you own a Nest Protect smoke and carbon monoxide alarm, you may be wondering how long the batteries will last. The answer depends on a few factors, such as whether you have the wired or battery-powered version, and how often the alarm is triggered. In this article, we'll answer some common questions about Nest Protect batteries and help you determine when it's time to replace them.
How Often Should I Change the Batteries in My Nest Protect?
Google does not prescribe a fixed 5-6 month replacement interval. Both battery-powered and wired Nest Protect use Energizer Ultimate Lithium AA (L91) batteries: the battery-powered model uses six cells, while the wired model uses three backup cells. Google says the battery-powered Protect warns when about a year of battery life remains, gives another warning when only a few months remain, and chirps when only a few weeks remain. Wired backup batteries are designed to last multiple years and, with a consistent power supply, should last the life of the Protect. Check the status in the Nest or Google Home app and follow the instructions for your exact generation; do not substitute alkaline or rechargeable batteries.
Sources: Google Nest Help: Replace Nest Protect batteries.
How Do I Check My Nest Protect Battery?
In the Nest app, select the Protect you want to check; its battery status and the time of its last Self Test appear on the device page. In the Google Home app, open Home, choose Smoke & CO, then select the Nest Protect. The app displays the reported battery status. A low-battery warning can also appear in the app and as a yellow light ring; when batteries are very low, the Protect chirps. App labels can vary by generation and software, so use Google's instructions for your model.
Sources: Google Nest Help: Replace Nest Protect batteries.
How Long Does Nest Protect Wired Last?
Do not confuse the wired model's backup-battery life with the alarm's expiry date. Google specifies that Nest Protect (2nd gen) must be replaced 10 years after its manufacture date. Check the device's Replace by date in the Nest or Google Home app, or on the back of the Protect, and replace it by that date. Google's current expiry guidance describes yellow-ring and chirp alerts; it does not support this article's claim that the unit flashes red.
Sources: Google Nest Help: Learn when to replace your Nest Protect.
Why do nest protect users need a replacement option?
Nest Protect's battery timing depends on its power model. Google says battery-powered Protect uses six Energizer Ultimate Lithium AA (L91) cells. It warns when about a year of battery life remains, gives another warning when only a few months remain, and chirps when only a few weeks remain. Wired Protect uses three of the same cells as backup; Google says those are designed for multiple years and should last the life of the Protect when power is consistent. Replace only with the specified cells and follow the instructions for the exact Protect generation—do not substitute alkaline or rechargeable cells.
