Not a great deal of sheddy activity here recently, for those who know me, but thought I'd mention this bit of tinkering.
Late last year I got (mostly out of curiosity) a battery charger that claims to recharge alkaline cells. It can accept AA and AAA cells.
I was a bit sceptical (partly why I got it) but it's... well, not bad, with caveats. Recharging is probably the wrong word to use here, it's maybe better to describe the unit as rejuvenating alkaline cells.
The more discharged your alkaline cells are, the less you'll be able to rejuvenate them.
(from experience) some cells will start leaking after you've charged them; it may not be apparent for a few days.
Some cells won't charge at all, even if they're not completely dead.
I had a wheeze where I thought I'd get free cells from the recycling points in most supermarkets. I helped myself to a few handfuls of old (and sometimes already leaky) cells from there.
Some of them did recharge/rejuvenate.
More surprisingly, some of them weren't very flat to begin with. People seem to throw out quite reasonable cells that just work with no problems.
To reduce the risk of cells leaking into equipment after rejuvenating, I test the cell beforehand, put it in the charger, test it afterwards (if it's not improved much it gets sent to the recycling). If it's taken a charge, it gets put in a cardboard box for a week or so. After that rest, if it's not started leaking, it's probably ok, so goes to the "good" pile after one final test on a battery tester.
Ian