Change Nest Thermostat batteries (Low battery message)

The Nest Thermostat receives power from your HVAC system. It also uses 2 AAA alkaline batteries as a backup, or to supplement if your system can’t deliver enough power.

This article only applies to the Nest Thermostat.

How to tell which thermostat you have

Low battery warning during setup

During initial setup, you may get a low battery message. This can happen if the batteries are loose or there’s a piece of the battery tab still stuck to the contacts.

1. Pull the thermostat display off the base.
2. Make sure you’ve completely removed the battery tab. Pull out the batteries from the back of the thermostat display and check that there aren’t any pieces of battery tab left.
3. Put the batteries back in and make sure they are fully seated and facing the right way.
4. Push the thermostat display back onto the base until it clicks into place.
5. If the low battery message doesn’t go away, replace the batteries with high-quality 1.5 V AAA alkaline batteries from a known manufacturer.

Low battery warning after setup

If there’s a power issue and the backup batteries get low, your Nest Thermostat will let you know with a low battery message in the Home app and on the display. You can easily replace the batteries with new ones. Follow the replacement directions in the last section.

Repeated low battery warnings

If you repeatedly get low battery messages from your thermostat, or if there’s another power-related message, you may need to check the C wire connection or install a C wire to provide consistent power to your thermostat and prevent the backup batteries from draining. Some systems, including heating-only, cooling-only, zone-controlled, and heat pump systems, require a C wire or the Nest Power Connector. Go to g.co/nest/cwire for details.

1. Replace the batteries by following the directions in the section below so your thermostat can control your system (and you can stay comfortable) while you check the C wire.
2. After you put in fresh batteries, go to Fix or connect a C wire for additional troubleshooting help.

How to replace the batteries

Important: Use only high-quality 1.5 V AAA alkaline batteries from a known manufacturer.

1. Pull the thermostat display off the base.
2. Remove the old batteries from the back of the thermostat display.
3. Insert the 2 new AAA alkaline batteries.
4. Push the thermostat display back onto the base until it clicks into place.

Note: You cannot replace the batteries for the Nest Thermostat E or Nest Learning Thermostat. Instead, charge the thermostat with a USB cable.