[Andrew B]

I fly radio model aircraft and change the battery packs every year, so after 20 years of flying, I have accrued lots of AA rechargables.

I invested in a conditioner/charger from a well known German supermarket chain that seems to deliver the beans. I use these>old< cells in most non critical things, clocks, torches, keyboards, mouse, radios, remotes, even putting them into D and C adaptor sleeves.

I use PP3 NiMH rechargables in my meters, even though they are a nominal 8.4 volts, I have never had a problem with accuracy, the "low battery" warning come on every 6 months or so.
They go back into the charger, which I believe works on "Delta" detect and the charger >conditions< them for 15 minutes, then goes to main charge, which takes about 2 hours ans leaves the cells feeling just warm to the touch.