Thanks for the quick responses guys.

First, regarding the possibility of a bad cell, it is possible, but unlikely as a month or two ago we replaced the battery. Although, it could have had a big load running on it... not sure.

The 11v could mean 11.9 volts, as it was the dealer that ran an AVR test on the altenator and the service guy said that it had less then 12 volts at idle, he didn't give me the exact number.

I would imagine during an AVR test, they don't have a huge load on the system? Not sure, never seen one run before!