96 QT30 T-plus here. Ours would throw the #8 battery alarm and it would always be the C/D cell looking battery on the memory unit below the axis drives. The batteries would measure fine out of the machine with a multi meter and no load, but when in the machine with a load they would read faulty instead of reading at or slightly above rated voltage. We went with a replacement battery with a little more capacity (same voltage of course)and we still end up replacing it once or twice a year.
