I did some work at two SEARS stores that were closing down and be liquidated earlier in the year, here in SoFla and I was given two 12v, 9Ah Duracell marked SLA/AGM batteries.
Since they were used and who knew how old they were, I brought them home and charged them up. I could get them to charge up to 13.05v with my Battery Tender Jr., but they’d soon settle down to 12.75v, which is still about 75% of rated capacity on its face.
The other day, I had them out to top off and decided that I’d hook my Maha C9000 to one of them and charge up 4 AA Eneloops. I set the charge to 500mA and started fiddling with other things. Upon inspection, 1 bay had stopped charging and the other 3 were down to 150mA, so I started things over and the 12v was just not up to the task. I got the wall wart out and finished them all off at 1A.
I have a couple of 02 Cool 12vdc fans for hurricane season and I’m sure that I could still get the fans to run on hi/low, for a bit, but that’s about all I can probably hope for?
I should just recycle them and be done with both, so we’ll see.
Life’s short and whether you can find a use for a ‘tired’ battery/cell, is ultimately up to you, but I’m starting to ‘bin’ a lot of these and opting to buy new, fresh stuff.
Chris