Nest 3rd gen Thermostat low battery issue after several years

[ErnieC6720]

After about 4 years, my NEST is now going to low battery and disconnecting from WiFi.  I can recharge with usb but doesn't seem to be charging on the wall.  Nothing has changed in my home.  Can these rechargeable batteries be replaced?  Could it be something else?  It hasn't happen before.  Maybe once after a power outage but never again.  Any suggestions would be greatly appreciated. 

[Rickyardo]

This solved my issues as well.  Smh, must have been some update that caused the issue.   But I am back to normal.  Thanks!

[ErnieC6720]

Not sure if this made a difference but I turned off the display sensing, so it no longer displays anything unless i manually interact with the thermostat and I have not had the low battery issue for a few months or any wifi  connectivity issues.  I also upgraded my home router but again, not sure if that made a difference. 

[Rickyardo]

I am/was having the same issues.  The tech support just had me disconnect the thermostat from the app/WiFi and that actually keeps it running.  Not a good final solution, but for people that need to keep their thermostats running, it may help someone.  
You can disconnect the Gen3 from app/WiFi by going to Settings->Reset->Account Connection

I did this a couple days ago and have not had the low battery issue (after full usb recharge) since.  Mine was lasting less than a day before.  

[Mingchan240]

Been working for the past 3 years now it's loses it charge every couple xays. Factory reset didn't help, now I am going to disconnect it from wifi and turning a $200 smart thermostat into a dollar store thermostat. This is ridiculous, I am not buying Google/Nest again

[jamiel8]

I bought 4 Nest gen 3 thermostats 5-6 yrs ago.  They were installed by an electrician.  One of them failed (repeated low battery, disconnected from wifi, shut down) with increasing frequency after 2 years.  The company sent a replacement, but the same thing happened 3 yrs later, and I finally replaced it again.  Now 2 of the other 3 are beginning to have occasional fails.  It seems the internal batteries have a limited lifespan.  A thermostat this expensive should last 20 years.  Still haven't found a thermostat replacement, so will soon have to replace more thermostats.

[jamiel8]

Follow-up:  Had an electrician install C wires for 2 of the 4 thermostats I own, including the one (2 months old) that I had to charge every few days.  Now the 2 are holding a great charge!  Think a C wire will extend the Nest thermostat life.

[Doctor_Homie]

Thank you blog post! You fixed my house!

Had the nest for 6 months and was working perfectly fine. 2 weeks ago it just said wasn't charging and would die. Would charge on USB then it would die after 5 minutes on the base.

Did factory reset. After done said needed to charge to connect to network. Didn't die after 5 minutes so it was a good sign. By this morning my husband had reconnected the WiFi and it's back to working perfectly without dying. Charge it maintaining!

Bottom line: factory reset fixed the nest low battery/not charging issue for me. 

[jamiel8]

I listened to advice here to connect a C wire.  Of my 4 Nest thermostats, had electrician rewire the 2 with heating and cooling functions.  The "lin" went from 20 or 40mA to 200mA.  The voltage is now excellent on both, including the one I recently replaced because of need for frequent charging (lin 20 previously for that unit, clearly not sufficient for battery charging and long life).  Electrician had to run a wire to the HVAC unit for one of them.  The 2 thermostats controlling only heat seem less stressed and run at lin 40, but I may have them rewired eventually.

[mhazen]

I have had this same low battery issue for months.  I have a 4 wire setup with no c-wire.  I also have a separate AC system and a forced hot water oil burner system.  I spent a lot of time debugging this issue, which seemed to start to occur after a May 2022 firmware update in my case.  I have had my Nest Gen3 for almost 2 years, with no issues until May.  Then this low battery issue started popping up.  I noticed that there was a firmware update a week before all my issues started.  I started charging it using USB to get the battery up to 3.8V to remove the low battery issue and that would only last for a few days before the low battery issue came back.  I fought with Google support, trying to get a replacement up to the last week before my warranty ran out and they kept blaming my AC unit (which was serviced and nothing was wrong with that.. just Google excuses).  So, being an electrical engineer, I started debugging this issue myself.  Here is what I found over a couple of months worth of fiddling.

1.  I stared charging with USB and figuring out how long it would take for the low battery voltage warning to come up.  It would take on the order of 1 to 3 days to come back after a USB charge.  The issue would start as a low battery warning and eventually it would shut down the network connection, as many have described.

2. I did these experiments for a few weeks and it was a consistent result of a low battery warning.  I could monitor the technical info and look at the voltage levels and it would go from 3.8V after the USB charge.. down to 3.5V after a day or 2.  So, obviously the recharge was not keeping up with the load on the battery.

3. I started shutting features off.  I methodically started picking features to disable to see if that would change the behavior.  After many iterations, the feature that seems to cause the issue is auto schedule.  I tried many different options.  When I shut off auto schedule on the Nest app from my phone app, the nest battery level actually went from 3.5V to 3.8V over the course of a couple of days.  When I first made the change to the auto schedule, the nest would not illuminate if I was close to the unit (the low battery indication was flagged)  The unit now seems to have charged itself back to the full 3.8v with no interaction besides shutting of their algorithm for figuring out how to optimize the settings.  Everything seems to be back to the way it was when I installed it years ago (well, other than shutting off their AI on optimizing the temp settings over the day).  I then went and reset the temp settings/times manually using the phone app, since the automation is shut off.  Now everything is working fine.

So, in my case, it seems that the Nest automation is taking up too much power and killing the battery.  I can still use the network to access the nest and basically it is working as a standard thermostat.  

I hope this helps others that are having similar problems.  I was at the point where I was going to rip it off the wall and put in a standard thermostat again.  Now, I'll stick with the Nest and just use it in this basic mode until maybe someday when Google figures out that they screwed up their software to the point where they kill the battery.

-Mike

[JiveJimmy]

My issue is different. I have a C wire. I thought the proximity detection was draining the batteries as it would come on many times a day due to its location. Disabling the auto temp display seems to be working but I miss seeing the temp when I walk by.

[EdB]

I've turned off the auto-learn and it still discharges after 2-3 days. Just recharged a couple of days ago. Will say after the 24 hour charge it lasted 6-7 days. It just bollocks as they say. Seems like some engineer(s) didn't do a good power study with the last upgrade. Taking a course in TinyML and one of the first things is accounting for a power drain. This is micro-controller design 101 stuff...

[endicott65]

Nest, Google and users owe you a big Thank You for tracking this issue down. I disabled auto scheduling and my Nest Learning Thermostat has been holding a charge for a week now. 

[Greygeek]

@mhazen- thank you for your writeup and study of the Nest issues.   I had a Nest Gen3 that ran with no C-wire and Auto-schedule + auto display turned on for over five years with no troubles.  But my system is heat only (3-wire connection).  I've read in other places that the Nest batteries do worse when Air Conditioning is part of the mix.  You might find that you can use the scheduling feature again if you turn off the A/C for the winter.    

  I recently replaced my Nest with a Honeywell T9 as we were tired of the winter discomfort from the large (un-adjustable) swing in temperature before the Nest calls for heat that is part of the Nest's programming.  

[mhazen]

I wanted to give an update to the post I gave last July.  While the changes I made helped a little bit, I still ended up having issues right at the end of the summer.  As I was starting to debug again, the cool weather hit in New England and I ended up changing over to using the heating system.  I have forced hot water (oil burner) and a completely separate AC system.  

1.  Once the heat came on, the battery in the nest recharged and all my issues went away.  I had a winter of trouble free nest usage. 

2. We just had a heat wave start yesterday - 88 degrees in April is rare.  I had to turn the AC on.  By this morning, the battery was already running low and the nest wouldn't light up if I approached it, which is of course the first sign the battery is running low.  Sure enough, the battery was at 3.6v or so, versus the 3.8v it was reading when in the heat cycle.

3.  There is a lot of talk about the Iin mA supplied by the heating/cooling system.  My heating system supplies 40mA.  The cooling on the nest reports 20mA.  I think this is where the problem lies.  Google must have made a change a some point that made any system that was borderline insufficient from a charging standpoint, not within the charging parameters it now requires.  It now basically required it to have a bit more current to keep up with the usage and battery charging. 

4.  Now the C wire is needed in these borderline cases.  In my case, I don't use the fan on the AC unit alone ever, so I used the Green fan wire for constant power on the AC (moved the green wire on the terminal block inside the AC unit) and moved it on the thermostat side from G to C - and labeled it C now, since it is a live wire (if you do this, shut off the AC unit first).  I am now seeing 200mA on the Iin on the Nest and the battery quickly was back up to 3.8v. 

5.  The Nest is smart enough to realize that the wiring configuration changed and also smart enough to realize that the power is only coming from the AC unit and completely disables the heating system.  So, when I need heat again, I'll have to either remove the C wire on the thermostat or figure out if there is a way to force it to heat mode and ignore the C wire and AC (maybe shutting off the AC unit at the breaker - but I believe that will give some warning message if I remember correctly).

In the end, it seems the Nest is a little particular about the current limit from the systems 24volt power supply that is available through the non C wire setup.  If you don't have a 40mA capable setup, then it seems that you may see issues like I have.

-Mike

[normallynat]

I have the same problem.   No C wire it was working fine for over a year and now goes offline frequently to conserve power.  Tried recharging the unit with USB then re-connect to the wall.   Soon after it goes offline again.  Did a factory reset.  This did not fix the problem.

[pgam]

Just experienced the issue on both of my 3-year-old 3rd gen Nests. I found the blue common wire was not hooked up at the thermostat nor the furnace, so I simply connected both ends of each common wire for both thermostats/furnaces, and it immediately resolved the issue on both units.

[rjp123]

Just had this issue pop up as well. Gen 3, been working fine for 5 years, now this. No C wire. 

Google's changed something with firmware and this has caused the issue. 

[nergmorts]

Confirming what many have said - Nest worked fine for 8 months then went to low battery and died - left my 80 year old mom with no heat here in New England in November. I had originally installed it with no "C" wire as instructions indicated it would work, and it did! Also all wires in wall were being used. Today took green wire from "G" terminal and moved to "C" as some suggested and it is now working again, at least in heat mode, will see what happens in spring when need AC.

[Tay_there]

I've had the 3rd gen nest for ~5 years with no issues whatsoever. Now my thermostat won't go more than 2 days without dying. It connects to wifi within instantly once it's charged and put back in the wall. Never had any issues in the past until this heat wave came. I'm wondering if that has something to do with it, but very frustrating to be woken up sweating  in the middle of the night. I've had this for so long I don't think they'll even cover the warranty. 

[Tay_there]

It fixed itself. May have been an OTA update..? Has been 24 hours since last dead and I am still able to connect via nest app. 

[EdB]

Interesting mine just went to low battery last night. So stopped measuring temperature in our bedroom and didn't kick in the cooling (there is a difference of at least 2 degrees between thermostat and master bedroom). So difficult for me to sleep. Woke up and manually set 2 degrees cooler so bedroom would cool to a comfortable setting.

[Autiomatic]

I’ve had my unit for 7 years without issue until just a few months ago when I began having the same problem described here. I recently installed the C Wire adapter and was hopeful that the problem had been solved (I charged the unit via USB while installing the adapter), but it’s giving me the low battery warning and has disconnected from Wifi again. I would be tempted to just go with another brand, but I’ve also invested in two of the temperature sensors, which would render those useless, although I guess if the thing can’t connect to the network anyway they already are. I’m going to start by turning off the autosense feature as posted above, and if that doesn’t help do the factory reset as well. Good to know the problem is wider spread than just me. Not going to bother calling customer support, and thanks to this thread I will avoid buying an after market battery replacement as it sounds like I’d still end up with the same issue.

** Update **
I did a factory reset and turned off the auto-scheduling feature. Not even 24 hours later and I’m back to low battery and disconnection from my temperature sensors. It appears I can still connect to the thermostat via the app, which I think has been the change since installing the C Wire adapter, but I must say that I’m quite disappointed overall. Hopefully they release an update to address this issue? 

[Spudly]

I am having the exact same experience.  After several years of issue-free operation, I suddenly now keep getting low battery warnings.  I agree with others that a software update caused this and can only hope a new update will address it.  I also need to learn my lesson and stop getting Google products.  Between what I read here and their habit of discontinuing products, not holding my breath on a fix.

[TXRick]

I just ordered 2 new batteries from eBay that I will swap out next week. Maybe that will help. Otherwise I need 2 new thermostats.

[Tay_there]

I have a theory.. Google has released a 4th gen nest thermostat. They bricked old devices with low battery to buy new one. 

[cedds1]

I see a number of replies suggesting that Google Support should be contacted. How do we contact Google Support? Thanks!

[EdB]

Open the nest app. In the upper left corner will be a down pointing chevron to left of the word "nest". This bring down a new screen. There will be an icon with an I in it. Select it for support.

[mjd]

5 yr old 3rd generation having same problem with low battery...

[normallynat]

There is a 3rd party replacement battery available on Amazon.  However it takes some skill and precision to replace it is not as straightforward as I expected it to be.  I actually gave up trying 😕

[rjp123]

People should stop trying to replace the battery. It is not a battery issue, it is an issue with the firmware which can only be fixed by Google updating it. 

[endicott65]

Which is apparently going to happen only when Hades freezes over... 

[DiBleu]

If you get an answer wouldn't that be great? Our a/c went out, but not before my Nest started acting up. Now we have been without A/C FOR 1 TOO MANY DAYS! It's been 100-106 for the last week and again all of this week. Nest app says not enough power for wi-fi. Charged  Nest via USB and I think it's charged. Good luck🙂

[Spudly]

I recently contacted Google support (chat) and we did a bit of troubleshooting (resetting, checking wires, etc.).  We also checked all the individual voltages and everything were within proper parameters.  The last step they did was to allow them access to my setup (for 90 minutes) and after poking around in there, advised me to manually disconnect from my wifi for 24 hours and report back.  I don’t know what they saw to lead them to this step and while I haven’t done it yet, it got me looking into battery/wifi complaints.  I found a thread on the Netgear forums of users having battery issues with their mesh wifi.  Issues that also started recently for them.  Some users found success with connecting their Nest to a secondary non-mesh wifi.  This suggests (after a Nest firmware update IMO) the Nest is now constantly bouncing between mesh nodes, draining battery.  I don’t have Netgear equipment but do have mesh wifi.  I’m currently playing around in those settings to see if I can find anything to bind the Nest to a specific node to see if that helps at all.  I don’t want to setup a separate wifi network.  Hopes this helps any of you and if it does, please let us know!  I will.

[UDntLikeItChgIt]

Scroll to the bottom for current status:  i.e. - currently works w/no change on my side on 3.6v.  I figured since I used this forum to get some answers, I'd offer my experience as well (unfortunately, I have no 'fix').

@Spudly , Disconnecting for 24 hrs, reconnecting, and reporting back your status... This is their typical response to have you focus on your wifi instead of something on their side.   They'll say:  "It worked / maintained a charge for the duration of being disconnected, and as soon as you connect it back after the 24 hr period, the battery drains to the point where the network is disabled - as designed...  Therefore it's your wifi / network that's the problem... For example: It's constantly looking for a wifi connection and draining the battery."  You can tell them that it connects immediately and is not 'constantly' looking for a signal... and you have router logs to show that it connects about once per hour and successfully obtains an IP address.  But that's where they start sending you links to help articles for setting up your wifi... "please contact your ISP for assistance in setting up your wifi...", etc, etc....  And if that doesn't work, they give you a link to buy a new thermostat. 

The 24 hr test only confirms that 'something' occurs during normal operations, related to network connectivity that results in draining the battery.  I asked for a list of things that the thermostat needs network connectivity for (how often it reaches out, etc), but that was ignored,  Essentially, my Support case boils down to an apology that my thermostat is no longer under warrantee and ~"they understand my concern / they would be upset too / they'd like to help, but cannot due to warrantee status". 

CURRENT STATUS:  In the end, my thermostat, left on the wall to be a 'dumb' thermostat, has recently (within the past week) resumed normal operations.  The crazy thing is that the battery's voltage is only 3.6x volts every time I check it.... this is far under the 3.7+ (3.8x) that Support has reported to everyone as being the required voltage to keep the network enabled.  I can confirm that NOTHING on my end has changed.... I can only assume that Google found their server side bug. 

Technical Info:  I have a Gen 3 Nest / Display 3.5 / Backplate 5.3 / Firmware 6.2-27 / Wiring:  Y1: cool, G: fan, Rc: power, and W1: heat

UPDATE w/more details:  I'll also add that the display is set for Farsight to be On and to display the Weather on approach.  It's installed in the hallway where people pass by throughout the day.  It worked for at least 5 years before this issue started.  While the battery supposedly drained, it never drained to the point where the thermostat failed to function completely, and the voltage would go up and down (very small increments) as I checked throughout the day.  (So it wasn't simply being depleted.)  Unfortunately, I have no idea what the typical voltage was before this issue started.  The current fix could be as simple as a server side update that instructs the thermostat to NOT disable the network when the battery voltage is below 3.7 or 3.6x, etc.

[Spudly]

Thanks for the information.  I will not waste my time following up with support at this point.   I did finally do the disconnect test and thermostat had no trouble keeping charge.  I have since done a full reset (again) removing both the thermostat and sensor from my account and re-adding.  Side note - when the battery stuff all started, I lost connection to the sensor and was never able to get it to reconnect until now.  Not sure what changed but so far it has maintained voltage above 3.7v and sensor has remained connected.  Let’s see if it lasts.

[endicott65]

Try disabling Auto-Schedule in the Nest app (per suggestion from another user). When I did that, battery voltage jumped up to a range between 3.6 and 3.8 and has stayed connected for a week. The Nest "Learning" Thermostat, 3rd Gen, no longer whines about low voltage nor disconnects from my Wi-Fi. Auto-Schedule never provided any useful information in 5 years or so. Kind of reminds me of Google's "tech support"...

[EdB]

I did that and it didn't help. Turned off the detect when I walk by sensor and auto-schedule and that didn't work. Some one else pointed out they have a mesh network. Seems like some change made by Nest has screwed up power usage. Looks like support is just following a script to drive us crazy and hope we just give up. Basically issue I've had with Google over the years is they just plain stop support their products.

[-MBS]

Would've been nice to know before I bought off Amazon...can't get a refund, now.

I'm have the same issue with my brand new unit, it lasted a month.

[rrobster]

Nest phone support was no help. My nest would not connect to the network or my phone hotspot (just to rule out a potential issue with the router). Battery readings were above the minimum needed to connect and I ended up buying a new one. The new one discovered the network within 15 seconds and works like it should. 

[Jeff]

Hey -MBS,

It looks like rrobster's issue was resolved by swapping out his unit, pointing to a hardware issue. You mentioned you couldn't get a refund from Amazon, is that due to how long you have owned the device, or was it purchased as used?

Thanks,

Jeff