Alan,
Looks like you were correct on the low voltage limit. I charged up last night, the 3s2p A123 pack starting voltage was down to 9.226V, it took 3850mah to charge to 10.95V. This morning I put up a test flight (I love this electric setup, I can fly in a suit, change shoes and then go to work it's great!!!!!) with the timer now set for 3mins. At the start the ship took off smooth with no sag at all. Did some climbs and divers, wingover, inside loops, inverted, horizontal eights and all was fine. It seemed like it was longer than 3mins but I was flying along and started a climb and once I nosed over the motor slowed then picked up, this continued for a while then it just went into the shut down mode and the ship landed with the motor just ticking over so I walked over and cut the power switch. Either I flew for a lot longer than I thought I had the timer set for (I did not time the flight separately, didn't think about that) or I have a weak cell. I plan to call MEC and see what they recommend.
Best, Dennis