NiMH batteries are surprisingly robust.

I've long had Palm Pilot Vx which I bought 2001 and used daily till 2011 when I switched my phone to iPhone 4s. Then I did factory reset and put it back in box it was sold and shelved it. End of January this year I was thinking I need to start clearing up what I've saved and see if would recycle, sell or send something to a museum.

I put Vx charging on its docking thing and left it there overnight (first checking it was not getting any warm) and next day I picked it up to see if it still works. It does, battery status did show full. I fiddled it perhaps almost half an hour and battery status was still full. So I left it on desk and thought to check it daily how long does battery charge last if idle. I think it was fourth of fifth day when change was only perhaps 10% percent. I have no real recollection of how much standby idle days was left after that 10 years in use, it's too long back and I didn't take any notes of it then. Just wrote in note date when I put it back in box.

I'm genuinely surprised that 25 years old darn thing still works, when it had been 10 years in use and then 15 years shelved batteries completely drained.

Now that's something we've lost when moved Lithium batteries, which don't survive being years completely empty. NiMH's just don't care, they seem to sustain capability to charge and keep charge after long periods of time unused.

I've had few NiMH triple-A batteries in use 12 years and I thought that was a stretch, but no. That Vx blew my mind how robust device and it's battery are.