Well, hmm. Ebay charger still running.
I unplugged it and put a 12v load (little air compressor) on one battery at a time, to try to get a surefire voltage reading. The first said 13.24. The second said 13.30, but I left it on for 15 seconds or so to see if it would change and it went down to 13.24.
These are MK gel cells and normally read about 13.13 when full.
I put the charger back on because I want to see if it will shut off pretty soon or if it is planning to charge my batteries till they explode. It's only 4amp max, so I figure it can't do a lot of damage in 15 minutes.
I really gotta get a second voltmeter to check this new one against.
Anyway, the batteries do seem to be about the same now, even if I am not sure WHAT value they share.
(I did have a charger go bad in such a way once that it charged my then-agms until they swelled up like they were pregnant. It is a thing.)