Nest Thermostat Low Battery – How To Fix

By Max Anthony •  Updated: 03/14/23 •  4 min read

Nest Thermostat Low Battery

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Nest is fully equipped to handle all kinds of unexpected events. Even though the thermostat itself isn’t battery operated, it has a battery that charges automatically if there is no power. During power cuts, the Nest thermostat will work for around 2 to 3 hours without power, before it fully shuts down.

You may be unable to use all the smart features which the product has when it is connected to a battery. Nest thermostats disable Wi-Fi connectivity so that they can only do what is necessary to heat the home and cool the people inside.

Charging the Battery

There are some cases when a Nest thermometer has run out of battery when it is needed, but this is more common when it is left untouched for a long time. Another possibility: It may be that you haven’t switched off your heating or cooling system for a while.

Your HVAC system supplies you with power, and that allows you to charge the battery that powers your Nest thermostat. When you turn off your heating and cooling system, your heating system stops getting power, and this causes your thermostat to start using the battery. That’s why you may see the warning that your battery is almost empty.

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To fully recharge the battery in the Nest thermostat, just do the following steps:

  1. Pull away from the display and look at the back of your thermostat. You should see a USB port for charging your battery.
  2. Use the USB port on the back of the thermostat to plug in a USB cable to start charging the batteries. You will need a USB adapter that works with the type of thermostat you have, which may be a micro or a small USB charger. It is easy to recharge the battery with an Android charger.
  3. Normally, your battery should last around 2 to 3 hours after being charged.
  4. Reconnect the LCD to the thermostat base, and then go to the Menu>Settings>Technical Info>Power.
  5. If your battery voltage is 3.8V, that indicates that the battery has been fully recharged, you should not have any warning signs on your battery.

Nest Thermostat Low Battery

Use a C-Wire Adapter

If power to the HVAC unit does not seem to eliminate the warning message, you can try applying this method. It is also useful if the C-Wire does not work or if your HVAC system does not supply sufficient power to your thermostat. Use a Nest-compatible C Wire adapter to add power to your thermostat. If you already have one of these adapters, simply put the items in the boxes given and use it as described.

  1. Shut the main power breaker off.
  2. From the adapter, install a wire to the C terminal and the second to the RC terminal. If your system contains a reversing fan, you’ll want to use a jumper to activate the fan and make it work.
  3. Connect the adaptor to the wall outlet, and then switch on the power at the breaker.
  4. Now, simply affix the faceplate to the thermostat, and you’ve done everything that you need to do.

Check the HVAC & the Nest Thermostat Wiring for Any Damages

The connection that runs from the thermostat to the heating system can get fried in some ways. Here are steps that you can take to see if any part of your wiring is faulty.

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Max Anthony

Mainly Max Anthony is an athletics tutor & lives in Texas but that's not it. He's is also a music producer, content creator, record producer, writer, and session musician. He has been producing music and engineering at a lower level for over 5 years. His passions include quality music gear and that's what he loves to write about on HifiBeast. ( Shoot him an email now )