I just wanted add some closure to this AIR battery life issue that I’ve had.
I reported the problem to WF and they decided that my AIR was probably faulty. A new AIR was sent out and its now in service with a fresh set of Ultimate Lithium’s (not bought from Amazon !).
The AIR has been in service for 11 days now and it is reporting voltages are noticeably more stable than my old AIR. I’m seeing around 3.5v and it hardly moves.
Wanted to thank WF for their support and this community.
cheers
Dave
I just changed my Air batteries after at least 3 years which is when the graph expires. They are probably my original batteries. I used alkaline Energisers as it never freezes where I live. But they did begin to create a green acid on a couple of the terminals.
cheers Ian 
I got similar life with the batteries in my Air. I don’t recall what I replaced them with; probably some run of the mill cheap batteries as my Air now resides indoors in my plant room.
This is an old topic but I am amazed by the battery life I have seen with my Air unit. The original Energizer Ultimate Lithium batteries finally died this past weekend after nearly Five Years of service! (install Nov 2017) Great job by Weatherflow in designing a very low energy system. Well done!
Yes, the batteries in my Air lasted nearly as long as yours before I needed to replace them.
I hate to bump an old topic, but I have started having issues with my Air. Using Durracell Ultimate Lithium batteries I am now going through a set a week, and when I take them out of the air unit they are very warm to the touch. This just started about a month ago.
Before that I would get about close to a year out of my air and a set of batteries.
I contacted support, hopefully its not an expensive fix.
That doesn’t sound good. I haven’t had to change any batteries in my AIRs since I first put the Energizer Ultimate Lithium batteries in. They are somewhere well north of 1000 days now. In fact, my oldest one is coming up on 4.5 years with the same batteries.
Support got back to me amazingly fast and said it’s dead.
But I have a new tempest coming my way.
Support was very good.