Nest Thermostat Low Battery Fixes and More (All Models)

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How To Fix Nest Thermostat Low Battery

Google Nest is one of the market leaders in the smart thermostat market, but what do you do when you get a Low Battery warning? I’ve got you covered with Nest Thermostat Low Battery fixes, symptoms and more for all the Nest models.

Let’s first understand what types of batteries they have, if any.

Does The Nest Thermostat Have a Battery?

All Nest Thermostats have batteries that act as a power back-up should there be a power outage or other failure that breaks the power supply to the thermostat. The type of battery that Nest thermostats use varies per device model: – 

  • Google Nest Thermostat: The Nest Thermostat uses 2 Standard AAA Alkaline batteries and can be replaced as required. Always use high-quality batteries to ensure proper operation and longevity.
  • Nest Thermostat E and Nest Thermostat Learning (3rd Generation): These two models use internal Lithium Ion batteries that are not designed to be easily replaceable by consumers. You’ll need to go to a Nest Professional service center to replace the Nest E battery.

How Do I Know When There is a Problem With The Battery?

Not all Nest battery problems manifest themselves in a way that can be easily identified. Below is a list of common symptoms and errors you might see from a battery problem. 

  • You receive alerts of a low-battery status and will need to shut down
  • The thermostat stops controlling your heating
  • It becomes sluggish in performance. Screen animations and menu scrolling are also very slow
  • The thermostat is not connected to Wi-Fi and appears as offline in the app or web-app
  • You get a notification to say “Please remove the thermostat from its base, then reattach it.”
  • It fails to light up when you are within range or when you try to activate it
  • There is a blinking green or red light above the display

These are the most common symptoms of a battery problem. Most of them are easily resolved, which I’ll cover in the next section.

How to Fix a Nest Thermostat Battery is Low

The basic Nest Thermostat batteries are the easiest to fix, because they use standard AAA batteries. The solution is to change them out with 2 new batteries. The other 2 models are a bit more complicated and laid out further down.

If problems continue to persist and the batteries drain faster than expected, then there is likely an underlying problem that needs to be addressed. Many of the steps below that address how to diagnose and fix low battery problems can be used to identify the problem. 

Before we address how to fix the issue, let’s understand what the Nest Thermostat battery does, the parameters it works within and how it charges under normal operations. This will give you a better eye to understand what’s going on and if it’s even a battery issue.

Understanding the Nest Thermostat Battery System

When there’s no power coming from the HVAC system, Nest batteries provide backup power. This could be as a result of a power cut, or an issue with the Heating System.

Under normal circumstances the thermostat uses the HVAC systems existing RH and RC wires, both to power the thermostat and charge the battery. And in most instances, a C-Wire is also required to ensure the battery charges and the system functions properly, for systems without this wire there is a C-Wire adapter that can be installed.

When everything is working fine, the battery should always have ample charge.Even if the heating system hasn’t been on for a prolonged time, the thermostat will switch the unit on from time to time, ensuring the battery remains charged.

Normally the battery operates between 3.6v and 3.8v, it’s when the charge falls below the 3.6v level that problems start to occur.

To check the status of the battery, use the control ring to go into the Settings menu on the thermostat. From there go to Technical Info and Power. In there, you’ll see a display showing the health of your battery.

If this sounds familiar or if you have any of the other symptoms listed above, then try the following solutions to rectify the situation. 

Troubleshooting Nest Thermostat Battery Issues

  • Restart the Thermostat: The old turn it off and back on trick often works. This is the first step to try and will fix the issue for many users.
  • Remove from the Base: Another quick fix is simply to remove it from its base and reattach it firmly.
  • Manually Charge the Battery: If these don’t work or the unit won’t even turn on, then the next step is to try to charge it manually. The Nest is equipped with a USB charging port. To charge the battery,
    • Remove it from its base, so you can charge using a wall socket or computer. Google recommends that the unit is turned when charging the Nest via USB. 
    • Charge the unit for ten minutes then remove the charging cable. 
    • If it has turned on during the charging process, turn it off, then back on again and wait until it is fully turned on.
    • Once this is complete, reattach the cable and let it fully charge for at least an hour.
    • After it’s charged, remove the cable and attach the thermostat back to its base. 

If problems still occur after the battery is charged, then there is an underlying fault. It could be a faulty unit or battery, but it could also be a problem with the existing HVAC system. More specifically, the type of wires, and the wiring between the HVAC and thermostat. 

Troubleshooting the Wiring System

This can be complex, but there are a few simple steps that can be carried out without too much technical know-how.

  • The first step applies only if you have recently set up a new thermostat for the first time and it has never functioned correctly. There are certain HVAC systems that aren’t fully compatible with the thermostat. Use this handy compatibility checker on the Nest Support Pages
  • Check if you have a C-Wire or Common Wire installed. Systems without a C-Wire can be problematic when it comes to batteries. If you don’t have one then there is an adapter that can be installed to fix this.
  • Use a multimeter to check if there’s any voltage on the RC and C wires (red and blue wires, respectively). This is an example of a multimeter on Amazon.
  • Check your fuse box. A blown fuse can stop the power getting to the thermostat.
  • Check the Nest Troubleshooting guide for any updates on potential power issues. 

Nest Thermostat Battery Life

If none of the above have worked and your wiring checks out, then it’s likely that you have a faulty battery.

Under normal circumstances you would expect the Nest batteries for the E and Learning models to last for around five years. While Nest has designed these to not be easily replaced, they can be replaced if you’re comfortable taking things apart with a screwdriver.

Of course, for the Nest Thermostat model, it’s a simple process with changing the AAA batteries. Otherwise, there is a quick how-to at the bottom of this article that will walk you through the stages. 

How Long Does the Nest Thermostat Battery Last Without Power?

The Nest Thermostat battery will supply back up power to the thermostat for at least an hour. Battery power could last as long as two hours depending on factors like Wi-Fi connectivity, HVAC system usage, and how often the menu is accessed. 

How to Replace Nest Thermostat Battery

In this section, let’s do a quick walkthrough on how to replace the battery on both the Nest Thermostat E and the Nest Learning Thermostat.

  1. Remove the thermostat from its base and ensure it’s turned fully off
  2. Place the Thermostat face down and remove the 4 Phillips screws
  3. Using the gray 20-pin connector, pull the back cover from the thermostat. Be cautious at this stage because there is a delicate ribbon cable that runs between the back cover and the thermostat.
  4. Unplug the ribbon cable from the mainboard of the thermostat. To do this, use the blue tab that is located at the socket, it should say ‘Pull’ on the tab
  5. The battery also has tabs marked ‘Pull’. Gently pull the battery upwards, use tweezers or fine needle-nosed pliers if you’re worried about pulling too hard. There’s a cable attaching the battery to the board so care is required.
  6. Gently unplug the battery from the mainboard
  7. Once clear from the mainboard and the display, the new battery can be installed by repeating the above steps in reverse.

For more on Nest thermostats, check out this article: ecobee vs. Nest Thermostats.