In alt.home.repair, on Sat, 14 Mar 2020 12:59:34 -0400, Wade Garrett
wrote:

Been using hearing aids for several weeks that run on size 312 zinc-air
button batteries. They last about a week then go dead along a very sharp
discharge curve.

I measured some used ones in a battery tester and their voltage has
returned to normal- around 1.45v. Not sure how long they'd last if tried
them back in the hearing aids- or it's a good idea to put them in there.

I might have been reading about hearing aids two or three days ago -- I
do read about them at times, but maybe it was something else this time
-- and one of the things it said was to not rely on battery testers.

But I doubt they will last more than a little bit Cars start pretty
reliably these days, but when they didn't, if you ran down the battery
trying to start it, you could wait a few minutes, 10 minutes, and there
would be enough juice in it to try once or twice more. The chemical
reaction had time to catch up and provide more ions. But those extra
tries were a small percentage of what a good, fully charged battery had
in it.

OTOH what have you go to lose? I'm sure they're not going to catch on
fire or drip or anything like that.