What Happens if Thermostat Battery Dies?

What Happens if Thermostat Battery Dies

What Happens if Thermostat Battery Dies?You may as well forget that you have batteries in your thermostat until the time comes when you ask what happens if your thermostat battery dies. Not much of a brain tax if you don’t have battery-powered thermostats, but you get the deal. Your thermostat will generally give you a warning on when the battery is dead. And if you ignore that, you’re in for deep trouble due to the poor performance from your heating and cooling systems.

Why your batteries need changing

We know someone who was off to the Bahamas and came back to find their home turned into the Sahara desert. Why, because the battery died while they were away, nobody cared to change because nobody remembered, and now they owned a giant oven to live in. The furnace kept running, and we don’t need to tell you it brings along the possibility of an inward explosion. So, you hopefully understand that you need to change it.

Signs that your batteries died

The most obvious sign you will ever receive about your battery dying is the low battery or battery drainage notification. If you don’t replace these, chances are you may need to reset your thermostat and, in extreme cases, return your thermostat.

Anyway, in most of the thermostats, there is an LED indicator that reads low battery. If the flashing of the low battery symptom isn’t enough, you may get a beeping noise that will warn you of your batteries’ timely death. What may also happen is that you may lose the display on the screen, and things can go black so that you cannot alter anything, make changes, or adjust the temperature. It actually varies, but chances are these are saying your battery is dying.

In some cases, your air conditioner and furnace may start to malfunction, since the stat can’t control what’s happening due to low battery levels. Even the backlighting fading from view can suggest that your battery is low.

How to replace batteries

This is as easy as you could ask for. The replacement of batteries is straightforward to do on your own, so you will hardly need help from anyone else. After handling everything we listed below by yourself, you will need to see if the HVAC is running well. If the heating and cool come off well, you did a great job!

To do the following, you will need a screwdriver, a coin, and nothing more than that. Don’t forget the new batteries!

  1. Press the tabs on both sides and release the thermostat from the wall.
  2. If it is screwed to the wall, bring it out via unscrewing.
  3. On the back or to the side of it, find the battery house.
  4. Pull out the batteries using the ribbon, holding them or inserting a coin to the battery house. You can also try by pulling it out gently. 
  5. Insert new batteries following the proper directions. Look for the positive end of the battery to the positive end of the house and the negatives together.


Obviously, it does. Batteries power the LED display that you see on your thermostat. They also power the transfer signal for temperature changes that you and your housemates notoriously tamper with. If there is not sufficient voltage, your thermostat will be unable to control what's in hand and perform poorly.

How long before I need to change the batteries?

How long your batteries last usually depend on what brand you prefer buying or what brand was suggested to you. Some batteries last a couple of months while others continue in years. If you are buying from the same manufacturer as your thermostat, you will get customized ones that last thankfully long.

Do thermostats have extra energy to run after batteries die?

No. Your thermostat can't run if the batteries are dead. Even if it is hardwired, it will call for backup. So it will be off-operation once the cells die.


Everything should be done now that you know what happens if the thermostat battery dies. But if your HVAC is not running correctly, the rooms are not heating and cooling as they should, you may need to consult a professional.