Sounds like that charger is either not set up right, or the discharge function has a prob. Accucel-6 you can't set it lower than 6v for a 2S on discharge.

I know you were curious and wanted to know what was left in your lipo, but this is the potential trouble ypou get into discharging a lipo and a good example of why not too, make a mistake or have a prob and the lipo is damaged or poss puffed and ruined. If those voltages were accurate, you prob have damaged the lipo internally and reduced its life. What you saw on charging might just be how quickly lipo voltage can recover. I see some big changes in voltage based on data recorder runs. The swings can be pretty big and very pretty quick.

Next time time your run and when you recharge it, calculate the mah/min that was consumed. Then knowing what came out and the capacity, you'll have a idea of what was left without discharging and risking the lipo.