All You Need To Know About Your Thermostat's Batteries

Programmable thermostats run on batteries, and one way to make them last longer is to stay mindful of this fact. Changing the batteries on time and using high-quality ones are the best ways to keep your thermostat in top-notch condition.

Here's everything you need to know about maintaining your thermostat's batteries:

What are thermostat Batteries?

Thermostat batteries are the main power source for programmable thermostats. These batteries are responsible for keeping your thermostat running and ensuring that it accurately controls the temperature in your home.

Why do Thermostats use Batteries?

Thermostats use batteries to provide a constant power supply and to maintain their settings even during power outages. This ensures that your desired temperature settings are not lost, and your thermostat continues functioning properly.

Types of Batteries Used in Thermostats

AA and AAA alkaline batteries are the most common types of batteries used in thermostats. Lithium batteries are also gaining popularity due to their longer lifespan, but they can be more expensive.

How Often Should You Change Your Thermostat's Batteries?

It is recommended to change your thermostat's batteries at least once a year, ideally before the winter season begins. This ensures your thermostat has a fresh power source and can function efficiently.

Signs Your Thermostat's Batteries Need Changing

Warning Display Sign

In most models, the display on the programmable thermostat indicates that the battery is low. It is displayed as a sign or a flashing light on the unit. This sign warns that the batteries will die within a month or two.

This means you don't have to run about panicking, trying to find batteries for your thermostat immediately. The warning usually shows weeks before. It's best to change the batteries before they completely deplete.

Dead Batteries

You should know your battery has died when your thermostat's display goes from running just fine to completely dead, with a blank screen.

It goes without saying that by this point, the thermostat will stop controlling the HVAC system, which can lead to muddled-up temperatures around the house. You can end up experiencing either excessive cooling in the home or excessive heating.

It might even turn the system off, leaving you without heating or cooling.

With these signs, you'll know that it's time to change the batteries of your programmable thermostat.

Temperature Fluctuations

One clear sign that your batteries may need changing is when your home's temperature fluctuates unexpectedly. If the thermostat isn't maintaining your set temperature, it might be due to dying batteries.

The thermostat Doesn't Respond To Changes.

When the batteries are low on power, you may notice that your thermostat doesn't respond to changes in settings. If you set a specific temperature and the thermostat doesn't adjust accordingly, it might be time to replace the batteries.

Reset Settings

If your thermostat resets your personalized settings to default, this could be another indication of low battery power. Regular battery replacement can help avoid such disruptions and keep your home comfortable, per your preferences.


Changing the batteries of a programmable thermostat is very easy and can be done at home. You can usually figure it out yourself; however, changing batteries differ from model to model. It is better to refer to the manual and follow the instructions given.

In most of the models, the process is pretty straightforward. You'll need to remove the battery compartment or the thermostat from the wall first to access the battery compartment easily.

Some Tips to Maintain a Long Battery Life

  • Make sure you replace all the batteries at the same time. Old and new batteries shouldn't be used in one device.
  • Whether the programmable thermostat requires AA batteries or AAA batteries, you must only make sure to buy alkaline batteries.  
  • Use the same kind of batteries, and do not mix batteries of different types in your programmable thermostat.
  • Heavy-duty batteries are often not suited for programmable thermostats. 

Follow the tips above and enjoy a long battery life and the long life of your programmable thermostat. 

Furthermore, even after replacing the batteries, your thermostat shows poor signs; contact our thermostat repair experts at MileHi HVAC today. 

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