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Thermostat Says Low Battery Even With New Batteries (Fix)

Usually, your thermostat will notify you with a “low battery” message on the display when its batteries are near depletion. The “low battery” notice is to warn you that you have to replace the thermostat’s batteries before the power level is so low that the thermostat loses some of its functionality.  But why are you now, after you’ve replaced the batteries, still receiving the message that the batteries are low?

A thermostat might still display a “low battery” message after you’ve replaced the old batteries with new ones. There are several reasons for this. The batteries might be damaged or substandard, or the thermostat has some technical or software issues. By troubleshooting systematically, the issue can usually be fixed by yourself.

In this article, I’ll discuss the most common reasons why you still get a “low battery” message after you’ve changed the batteries and provide possible troubleshooting procedures and solutions to fix the problem. Most of the troubleshooting procedures are, in principle, the same for all thermostats, irrespective of the brand and model of the thermostat. In this article, I mainly discuss the general procedures and only refer to Honeywell and LuxPRO thermostats in a few instances where they have brand-specific procedures.

1. Replace substandard or bad batteries

The problem

Even batteries manufactured by well-known brands can sometimes go bad. And there are also substandard batteries on the market. If you’ve inserted bad or substandard batteries into your thermostat, it might be that they just don’t have enough power for what your thermostat needs. If this is the case, your thermostat senses that the batteries will soon not have enough power to keep the thermostat going, and thus, the low battery message will still be displayed.

Another reason why the thermostat still shows the “low battery” message after installing new batteries, is that the terminals may be corroded.

Possible solutions

Your first troubleshooting action should be to replace the batteries again with fresh batteries. Use the brand of batteries recommended by the manufacturer, or at least the best batteries you can find at your local dealer.

Regarding the corroded terminals, remove the batteries again and clean the terminals and when you put the batteries back again, ensure that they make good contact with the terminals.

If this procedure doesn’t solve the problem, you’ll have to troubleshoot further. 

2. Rectify a temporary hardware issue with power cycling or hardware reset

It might be that your thermostat is encountering a temporary hardware issue or is not receiving enough power. This can cause the “low battery” message. If this is the issue, it can be rectified by resetting the thermostat with power cycling or hardware reset.

Power cycling or a hardware reset won’t erase your temperature settings and other data. It only refreshes the thermostat. It usually fixes minor problems, such as a “low battery” message after you’ve changed the thermostat’s batteries.

Procedure applicable to most brands and models

To power cycle your thermostat or do a hardware reset, follow the following steps:

  • Put off the circuit breaker servicing the thermostat to ensure that no power is flowing to the thermostat.
  • Take the thermostat off the wall, open the battery holder and remove the batteries.
  • Wait for about 15 minutes and then put the batteries back into the thermostat.
  • Turn on the circuit breaker. Remember, to put a circuit breaker on, you have to press the switch down completely and then press it up until it clicks into the “on” position.

If the problem is not resolved, you have to keep on troubleshooting.

Procedure for a Honeywell thermostat

If you have a Honeywell thermostat you can easily do a hardware reset.

To start this procedure, remove the thermostat from its baseplate on the wall. Remember to put off the power supply to the thermostat before removing it from the wall. The best way to ensure that the power is off is to turn off the circuit breaker servicing the thermostat.

After you’ve removed the thermostat from the wall, remove the batteries, and then press and hold the black button labeled “HW reset” for 5 seconds. Then wait 5 minutes and install new batteries. Replace the thermostat on the wall, turn the circuit breaker on again by pressing the switch down completely and then press up until it clicks into the “on” position. Reset the thermostat’s date and time.

If the warning message is still displayed you’ll have to look for other reasons.

Procedure for a LuxPRO thermostat

The procedure is in principle the same as described above for the Honeywell thermostat. Just follow these steps:

  • Remove the thermostat from its position on the wall. (Remember to cut all power to the thermostat before removing it.)
  • Remove the battery cover and remove the batteries.
  • Wait for 15 minutes and then replace the batteries and the cover.
  • Locate the hardware reset button on the side of the thermostat. It is a circle button labeled “H.W. Reset”.
  • Long press the button for a few seconds.

If this procedure hasn’t resolved the problem, continue troubleshooting.

3. Calibrating your thermostat might solve the issue

There are technicians and thermostat manufacturers who believe that recalibrating your thermostat might solve the problem of the “battery low” message which stays on after you’ve changed the batteries. The way how to calibrate a thermostat differs from brand to brand and even from model to model. So, consult your thermostat’s manual for details. Just remember that you might have to program your custom settings and schedules again after the calibration has been done.  

As an example of what the calibrating process entails, I’ll briefly explain how to calibrate a Honeywell thermostat.

You can do the recalibrating yourself. Just make sure that you have an extra set of new AAA batteries with you as you will use two sets of new batteries during the procedure. To calibrate your Honeywell thermostat, take the following steps:

  • Take out the battery compartment from your Honeywell thermostat and insert a set of new batteries.
  • After 10 to 15 seconds, take out the batteries and put them in reverse polarity back into the holder.
  • Put the battery compartment inside the thermostat and wait for 10 to15 seconds.
  • Then take out the battery compartment again and replace the first set of batteries with the second set of batteries – this time in the right polarity position.
  • The last step is to put the compartment back.

If this calibration still does not solve your problem, you have to try another solution or contact your professional technician.

4. Honeywell specific solution- Turning the Control Feature Off

The control feature of your Honeywell thermostat is the feature that takes care of your home’s heating and cooling systems. Sometimes, they can get bugs or other issues that might result in a “low battery” message on the display.

If you are running out of the “easy” troubleshooting options this is something you can try. Take the thermostat off its baseplate on the wall. Before you remove the thermostat, put off all the power supply to the thermostat by turning off the circuit breaker servicing the thermostat.

When you’ve removed the thermostat from the wall, go to “Settings” and then to “Cooling/Heating” and turn it to “Off.” Take the battery compartment out of the thermostat and disconnect the “RED” wire which is connecting to the back of the thermostat.

A very important step now is to wait for an hour before you reconnect the RED wire exactly where it was connected before. Then insert a new pair of batteries.

This procedure might fix the “low battery” message issue on your Honeywell thermostat.

5. Last resort – Reset your thermostat to factory settings

I recommend this as a “last resort” because a factory reset will, in most instances, solve the problem, but after you’ve done a factory resetting, all your custom settings and schedules will be gone. You will have a “new” thermostat which you will have to program from scratch. This might be time-consuming.

Procedure applicable to most brands and models

  • Power off the thermostat by turning the circuit breaker off.
  • Remove the batteries.
  • Replace the batteries incorrectly, in other words, with negative to positive and positive to negative.
  • Wait ten seconds, take the batteries out again, and put them back correctly.

Your thermostat will now be reset to factory settings, and you can reprogram it.

Resetting your Honeywell thermostat to factory settings

To reset a Honeywell thermostat to factory settings, follow the next procedure:

  • Press and hold the “Weather” button on your thermostat for 10 seconds, or until a “Menu” appears on the display screen.
  • Select “Factory Reset” and then “OK.”
  • The thermostat will prompt you to confirm the factory reset. To continue, choose “Yes.”
  • Wait for at least 5 minutes and then configure your thermostat’s settings from scratch. Your “battery low” message will now be gone as you now, in fact, have a brand new thermostat.

However, if your thermostat is still giving the message, you’ll have to contact your HVAC technician.

Resetting your LuxPRO thermostat to factory settings

To reset your LuxPRO thermostat, you have to disable the keypad lockout on the thermostat. Then switch the thermostat to the “Off” position. The next step is to press the “Set” and “Next” buttons simultaneously for 5-6 seconds. Keep the buttons pressed and wait until the LCD screen is fully populated. Then release the buttons.

Possible other reasons for the issue which are not battery-related

Sometimes an issue not related to the batteries as such might cause the “low-battery” warning to stay on even after you’ve changed the batteries. I recommend that you consider the following aspects as possible reasons if none of the other troubleshooting procedures has rectified the problem. You most probably will need to consult with your HVAC technician to find and fix these problems.

Bugs, glitches, and viruses

Remember, like all devices working with Wi-Fi, your programmable thermostat working on Wi-Fi is vulnerable to viruses.  If bugs, glitches, or viruses get into the thermostat system you can receive false messages regarding issues that actually don’t exist. If you suspect that this might be the problem the best is to call your HVAC expert or your thermostat manufacturer’s help desk.

Wiring and cables

There can also be faults with the wiring or the cables reducing and even prohibiting power flow to the thermostat. If you are not a certified electrician, it is better not to try and solve this yourself – consult with qualified professionals.

Final Word

When your thermostat keeps on displaying a message that the batteries are low even after you’ve changed the batteries, it is usually not a big issue, and you can troubleshoot and fix it yourself in most instances. The guidelines in this article should help you to rectify the problem quickly and easily.  

FAQs

Q: Do I need to reset my thermostat after changing the batteries?

Usually, when you’ve changed the batteries of your thermostat, you don’t need to reset it. You only reset it if there is a problem, such as the “low battery” message staying on the display, or the “normal” troubleshooting is not working.

Q: Do I have to use alkaline batteries in my thermostat?

Most thermostat manufacturers recommend alkaline batteries. It is always good practice to use alkaline batteries because other batteries often and may cause severe problems, especially if the battery holder is located inside the thermostat.