Nest Thermostat very low battery (iPhone app notification)

[Maltz]

Received a very low battery notification via my iPhone app for my Nest Thermostat but I my unit is hard wired to my HVAC. Nest support is saying that I have to replace batteries or the thermostat will shut down.... but I thought the batteries were just backup and shouldn't really matter? 

[Patrick_Caezza]

Which Nest thermostat do you have, and how is it wired?

The Google Nest Thermostat (mirrored) requires a C wire for several types of systems.

[Maltz]

Thanks!! Really appreciate the repy! We have the mirrored and pretty sure they ran the C wire

[Jenelyn_O]

Hi there,

Chiming in — if you repeatedly get low battery messages from your Nest Thermostat, or if there’s another power-related message, you may need to check the C wire connection if it's getting power from your control board, to prevent the backup batteries from draining. Also, you can visit this article for more information.

Thanks for your help @Patrick_Caezza.

Best,

Jenelyn

[Markjosephp]

Hello folks,

Thanks for the information about the C wire, Jenelyn.

@Maltz, I wanted to see if you still needed help. Please let us know if you have any other questions or concerns.

Regards,

Mark

[Maltz]

Thanks for checking in! The C wire was connected but I didn't want to risk the system shutting down so i just changed the batteries.

[Markjosephp]

Hey there,

I understand that this step is a little out of the way, but could you please check your thermostat's power readouts instead? This will assist us in determining whether it is recognizing the common wire.

1. Go to your actual thermostat's Equipment settings and then Power Info.

I'll look forward to your response.

Regards,

Mark

[Maltz]

Hi Mark. Can I do this via the Nest thermostat app?

[Markjosephp]

Hello Maltz,

Good question. Unfortunately, power readouts are only available on the actual Nest Thermostat settings, as it reads the real-time voltage from the connected wires.

Let us know how it goes so we can more forward.

Thanks,

Mark

[Markjosephp]

Hi there,

It's me again. I'm checking back in — how's it going? Were you able to gather the power readings on your thermostat?

Thanks,

Mark

[graussofj]

Hi Mark,

Here is the background for my problem:  

I asked this question and didn't get a  useful answer, and the conversation was closed out before I checked back.  "I have two Nest Nest Model 1.4 Thermostats installed with power connectors to a Energy Kinetics System 2000 Energy monitor on an oil-fired boiler with to hot water zones.   With a lot of hassle with the wiring of the power connectors to the System 2000 Control and help with the community, I successfully installed the thermostats and they were working perfectly for one day.  These were installed at my church, so I am monitoring them remotely.  This morning I got a "very low battery  - replace immediately" notification on one of them.  I checked the device info and it indicated the battery level as 3.22 V and reports the battery condition as "very low."  I checked the other thermostat and it reports a 3.03 V battery voltage and battery condition of "OK".  Both report that the Power Connector is connected.  I am getting no Error codes.  Does anyone know what could be going on here?"

The first time I got this error, I went back and removed the batteries, tested them and found them each sufficiently charged.  I put them back in and thermostat restarted with no alarms.   A few days layer I got the same notice that the battery was very low, but in device information it was still reading 3.2V.  I then ignored it.   It then went offline.  The last alarm that was sent reported the battery was very low, but the voltage was 3.17V.  After calling the Help line, I spoke to someone who said I needed to go to the thermostat location to get measurement data.  When I got there  I did the same thing as last time, and the thermostat restarted but it was giving me a N260 error.  After playing with the power connector, I decided it must have gone bad, so I finally gave up and relocated the thermostat so I could install a C-wire.  After this, the Thermostat worked fine and I never went back to the thread and it closed out on me because I felt I had solved the problem.  Well after three weeks of proper operation, I got a low battery notification.  The thermostat is still online and seems to be working perfectly, but the battery voltage is reading 3.05V with a  very low state in the device information on the Google home app.  The last note I got from you asked whether a C-wire was installed and what model thermostat it was. It is a Nest E model with a C-wire installed. The last time I ignored the alarm, it went offline.  What do you suggest I do?  Do you think that it is a defective thermostat?

[graussofj]

Hey Mark,

I am getting a very low battery alarm on a Nest E thermostat on my app.  The voltage on the app is reading as 3.05 V, the Nest is on-line and I can control it on the app.  My question is, will the thermostat take itself off line if it believes this false alarm?  When I had this problem before, I checked the batteries and they were fine.  When I plugged it back into the wall, it restarted and the alarm cleared and battery voltage was as it reported before.  I am controlling this thermostat remotely as it is in a building a half hour ride from my house.  The last time I ignored this type of message, it took itself offline. Is this a software issue or a defective unit?

[Maltz]

I clicked on the Thermostat settings:

VIN: 34.449V

LIN: 385

PS: C-385

[graussofj]

I have a similar problem. I get a very low battery alarm with battery voltage of 3.05V reported on the app.  It is connected via a C wire.  I have corrected this situation before by removing the batteries, checking their voltage to find that they are both reading over 1.5 volts, and putting them back in the system.  When I replace the thermostat on the wall, it restarts, alarm clears, and voltage is as reported earlier.  Two weeks later, same problem.  Does this sound like a software problem, or a defective thermostat?

[Maltz]

How do you check the battery voltage on the app?

[graussofj]

Open the household. Tap the thermostat you want information on.  Go to upper right hand corner of the thermostat display and tap the settings icon.  On the menu list, tap Device information, scroll down and see the Technical information and at the end of the list is the Battery state and the Battery voltage.

[Markjosephp]

Hello folks,

I appreciate your thoughts about this, @graussofj. We'd be happy to take a look at this for you.

@Maltz, the battery voltage option is only available on the actual thermostat.

Could you please fill out this form with the needed information? A member of our support team will be in touch over email to help.

I'll look forward to your response.

Regards,

Mark

[Maltz]

I clicked on the Thermostat settings:

VIN: 34.449V

LIN: 385

PS: C-385

[Maltz]

I clicked on the Thermostat settings:

VIN: 34.449V

LIN: 385

PS: C-385

[Markjosephp]

Hello Maltz,

Thanks for keeping me in the loop. We'd like to investigate this further and try to check for more options.

Please fill out the form and let me know once you're done.

Best,

Mark

[Markjosephp]

Hi there,

I'm checking back in — how's it going? Have you managed to fill out the form? 

Best,

Mark

[Maltz]

I replaced the batteries and everything seems to be back to normal so I think I'm set. I'm just not sure if the system would've shut down if the batteries died - that's all. Seems like I need to check-in with my HVAC co. since they're the ones who set it up. Thanks for the follow up Mark.

[Markjosephp]

Hello Maltz,

That's a relief! I'm glad to hear replacing your thermostat's batteries resolved it. In the meantime, try observing its behavior, and if the same issue persists, contact the installer for an HVAC inspection.

Feel free to let us know if you have more questions.

Regards,

Mark

[Jenelyn_O]

Hi folks,

Checking if you still need help. Please let us know if you have further questions or concerns.

I appreciate your help, Mark.

Thanks,
Jenelyn

[Maltz]

All set. Don't need anything else. Will check with my HVAC co. Thank you for the help. 

[Jenelyn_O]

Hey Maltz,

Thanks for the update. I'm glad to hear that! Please be advised that I'll be locking this thread after 24 hours. 

Best,
Jenelyn