Nest Learning Thermostat Battery Power

[Grifreaper]

Recently had to update my thermostat from an older model of Nest to the Gen 3 Learning Thermostat (optical sensor died in the old one); but the new one has an almost constant Low Battery warning. I checked the wiring, and about everything listed in the E74 error page. I've installed a Nest Power Connector, but still see low battery sporadically throughout the day. Any ideas on if this should be expected or if I should be concerned about it?

Battery Stats are sitting at the following.

Battery: 3.704 V - 3.667 V

Voc: 39.16 V

Vin: 37.18 V

Lin: 40 mA

Not sure if running a wire directly to it from the C connector on the thermostat would do anything at this point since it's already in "use" by the Nest Power Connector at this point.

[Markjosephp]

Hello Grifreaper,

Thank you for taking the time to let us know about your inquiry. I'd love to know more about this.

Could you share a photo of how you installed your Nest Power Connector, showing its wiring connections? Also, please restart your thermostat by pressing and holding its screen for 10 seconds until it shuts down.

I'll look forward to your response.

Regards,

Mark

[Grifreaper]

 Due to the size of the files, I've uploaded them to my google drive. You should be able to see the images here:

https://drive.google.com/file/d/1fUMdHAA8s8j6d1LxGEt-_tb7NBIYcU38/view?usp=sharing, https://drive.google.com/file/d/1faEW5CI3bw994Sg4ZkkgS62J90c6_a58/view?usp=sharing

[Markjosephp]

Hi there,

I'm sorry for the late reply, and thanks for sharing the photos. Big help!

It appears that there are 3 wires, including one from the Nest Power Connector, connected to the 24 COM terminal. Incorrect wiring might cause damage to the device and to your system. Please make sure to follow the corresponding terminals for the installation. Here are some references to help you install your new Nest Power Connector on your HVAC system.

• Nest Power Connector installation article
• How to install the Nest Power Connector - video link

Please let me know if that helps, or if the issue still persists.

Regards,

Mark

[EmersonB]

Hello everyone,

@Grifreaper It's us again. I'm bumping up this thread to ensure that everything is covered here. Were you able to read the information and check the links shared above? In case you have an update, you know where to find us.

I appreciate the help, Mark.

Best,
Emerson

[EmersonB]

Hi Grifreaper,

Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know.

Thanks,
Emerson