Nest learning battery keeps losing power

[tedzmd]

I have used this Nest for several years without any issue.  Lately, it keeps losing power and requires recharging every few days.  I have never had a common wire and don't understand why I would need one now.  Does the battery fail after a few years?  If so, can it be replaced?  Who would do this kind of task?  Thank you.

[David_K]

On your thermostat, go to the Settings cog > Technical Info > Power. If the special Voc, Vin, or lin values are not within the specific ranges listed here, you may have a wiring or system issue.

You may need to connect a C (common) wire or Nest Power Connector to your thermostat. If there’s a C wire connected to your system’s control board, you can put it in the thermostat’s C connector to check if that helps. Here are instructions on how to check. If you've used your thermostat for years, it's probably unlikely that this is the case for you, but I've included this for transparency. 

This can also happen due to a problem with your system and it may need maintenance for a variety of reasons. For example, a clogged air filter can cause your system to overheat and automatically shut off. When this happens, your Nest thermostat can't draw power from your system to charge its battery. You may also find a Furnace Heads-Up message on the thermostat screen, in your app messages, or in your monthly Home Report email.

If you're in doubt, or need support, we recommend contacting a local HVAC professional to service your system and check your thermostat wiring.

[tedzmd]

Thanks so much for your quick and informative reply. The technical info shows all levels are within the range except for the lin - mine is 40 mA.  Does that give you. any information that helps diagnose my problem?  Again, for several years it has worked without issues. Can the battery be replaced in one of these? 

[David_K]

For troubleshooting, I'd recommend using the Nest thermostat troubleshooter and select Power issue.

[Jenelyn_O]

Hi there,

Thanks for posting in the Google Nest Community forum. I'm sorry for the delay. I just want to check if you managed to see the response above. Please let us know if you still have questions or concerns, as we'll be willing to assist you further. 

I appreciate the help, @David_K.

Best,

Jenelyn

[Jenelyn_O]

Hi tedzmd,

I wanted to follow up if you still need help. Please let me know if you’re still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Thanks,

Jenelyn