Nest thermostat low battery

[wrasmus]

I set my Nest thermostat to have the fan "always on". Now I cannot turn the fan off and my thermostat seems dead. It was showing a low battery so I charged it overnight via the usb port. I reinstalled it and now have a blinking blue light and blank screen. It acts like it is dead. It has been working fine for at least 4 years but now has battery and connectivity issues.  Any ideas?

[David_K]

A pulsing blue status light on your heat link means its ready to pair with your thermostat.

Heat Link lights and what they mean

Did you try pairing it again?

How to pair the Nest thermostat and Heat Link

[wrasmus]

Thanks for the quick response. It won't connect to the internet and indicates "low battery" . I charged the thermostat overnight via the usb port and I have 40 vdc from the furnace. I am wondering if it is a bad battery that will not take a full charge. 

[David_K · Accepted solution]

Which generation of learning thermostat do you have?

How to tell which Nest thermostat you have - Google Nest Help

On your thermostat:

1. Go to Settings > Technical Info > Power.
2. If the Voc, Vin or lin values are not within the specific ranges listed here, you may have a wiring or system issue. Expand the "Power" section of the article, and see the "Voc Vin lin" section.

[wrasmus]

Thanks for the link to the power requirements.  This is what I get:  Battery 34.15, Voc 34.01 V, Vin 34.93V, and lin 30mA(I). Problem appears to be with the power to the thermostat. Thanks again

[Markjosephp]

Hello folks,

Thanks for the help, @David_K.

@wrasmus, I'm sorry to hear you're having an issue with your Nest Thermostat that won't hold its charge. I'd love to know more about this.

• Are you getting any message codes or reports aside from the low battery alert?
• How long have you been using your thermostat, and when did the issue occur?
• Did you encounter any internet connection issues or power outages recently in your area?
• Do you have a C wire?

I'll look forward to your response.

Regards,

Mark

[wrasmus]

Thermostat was 3 years old and low battery prevented any connection to the app or to the internet. Installed the Nest Power Connector and the thermostat charged up overnight and is now working correctly. I do not have a C wire installed to the thermostat. 

[Markjosephp]

Hello there,

Sounds great! Thanks for the update that you installed a Nest Power Connector. I wanted to ensure that everything was covered here. Could you please check its current power readings?

Keep me posted.

Best,
Mark

[wrasmus]

Battery: 3.863  Voc: 34.73 Vin: 31.45  lin: 40mA

[Markjosephp]

Hello wrasmus,

Perfect! It appears that there's progress between the battery level and the Lin. In the meantime, please continue monitoring your thermostat's behavior and don't hesitate to give us a shout if anything comes up. Also, I wanted to ensure you are good to go; please let me know if you need more help. Otherwise, this thread will be locked within 24 hours.

Regards,

Mark