The only way I know of to "test" the condition of gelcell and AGM
CAPACITY is to watch how LONG it takes them before their charging voltage
gets to 14.2 or 14.3V. If the acid has been eaten up and cannot be
recovered, every boaters smiles away because he saw the "meter" rise
QUICKLY to 14.2V "in the GREEN" in 20 minutes at 10A. 10A x .33 hours =
3.3AH, the remaining capacity of these hosed AGM babies all sulphated to
hell. A "good" dead AGM battery won't come up for HOURS at 10A....10A
for 13 hours = 130AH, for instance.....NOT 20 MINUTES. If the dead AGMs
rise quickly, they're HOSED and need replacing.

i contacted another buyer (a boater) and she said

"Hi, mine had 10.5V and took about 4 hours to charge (less than I
thought) and seems to be holding the charge without problem."

that seems a bit suspicious to me.