Cameron SinoCameron Sino Li-Polymer 3.70V 380mAh/1.41Wh Battery Compatible With Nest TL284443, Fits Nest Learning Thermostat 2nd Generation,Learning Thermostat 3rd Generation,T3007ES,T3008US

I don't like the new Google thermostat I prefer the old nest thermostat works well but unfortunately the battery it has inside for redundancy once it goes bad the Wi-Fi and other features start dropping out. At first I thought it was intimidating to replace the battery but after I did it it's pretty easy and it beats buying a new nest thermostat for no reason just because of a battery

First, this battery is of lower capacity than the original Nest battery. About 30% lower. Which would normally mean that at full charge, it should last about 30% less. But it doesn't even last one day. It is just a very low quality battery. It fits and it's not all that difficult to install, but it doesn't work. I'll hold on to the Nest until a real replacement battery becomes available, until then I had to buy a new thermostat. Obviously not another Nest with non-replaceable battery.

Well this is the second one I got, different brand. Had to take apart twice. First time after charging battery and then putting on wall it didn’t fire up. Took apart and try again and it works so far. Little difficult to changing battery. Connector wasn’t set right on battery at first I guess. Little tricky.

Update: About a day after the install the new battery went low. I'm one of the situations that does not have a wire attached to the C terminal--and no spare conductor. I ran a new cable from the Nest to my air handler above and connected a conductor between the Nest C and the air handler. Nest now reads "24 volts common" at that terminal but says the RH conductor is attached to the Nest but nothing at the other end ("power" label is dimmed). Fortunately when I tested the heat it does come on. 36 hours later I still have good voltage at the Nest and it remains connected to Wi-Fi. So I'm good to go. Bottom line is don't buy a new battery if the Nest is running separate heat and AC units and you have nothing connected to the C terminal. You need that to complete a battery charging circuit. Without it all you have are switches in the nest to complete circuits to turn on heat, a/c and the fan--no common/neutral.So do the C terminal fix first (several ways to do this--Google it), then decide if you also need the new battery. I'm keeping the original review up since I think it condenses several tutorials you can find here and on YouTube. No deduction on the battery review as the failure to fix the problem was not a battery issue.Original review:Not terribly difficult if you have the proper Phillips head screwdriver and some patience. Check some of the YouTube videos--with caution as some say to remove four screws from the first plate. Others fail to mention that you have to twist that cover counterclockwise before it comes off.Back cover #1 comes off with just two screws (no need to remove the two around the electrical connection)--they were on very tight for me--and a slight twist of the cover counterclockwise to release it from the second layer. Then remove the second layer's four screws. Now you can move these two covers and the outer bezel out of the way to expose the board and remove the battery (and its connectors) from that board. My original battery was glued on but not difficult to carefully pry off. Enough adhesive remained to place the new battery on.The battery they sent me had short connector wires just like the original. My Gen 3 had a small square neoprene insulator over the connection that I removed with tweezers, then carefully pulled the connector straight off the board. A small jeweler's straight screwdriver helps to pry it off. Carefully note the position of the red and black wires so you can press the new one straight onto the board. A small screwdriver will help press the new one onto the that very small connector. A tiny dab of rubber cement on that neoprene square glued it to the top of the connector.Reassemble in reverse order. You have to play around with the circuit board to get it inside the outer bezel. The four screw plate goes on next and you have to carefully line up the screw holes on the plate with the mates on the circuit board. Don't overtighten these--just snug. Finally the outer back cover with two screws tightly. If you don't get these right the thermostat won't press/click for the various settings and you will need to go back reassemble it.Finally use an android USB to charge it for an hour or two before remounting. When you plug in the USB it will come to life so you know you got the connector on the board correctly.The one star deduction is not really for the battery. I agree with others that Nest should have designed this in a manner that makes the battery easier to replace. But it's doable and a whole lot less expensive than replacing the whole device.

I didn’t get a chance to use this battery cause the tiny connectors on the nest broke while I was installing this battery.