Using your method I would stay with the 7.1v cut off point and definetly go no lower than 7.0v before recharging. I would also always top off before the first flight of the day regardless of voltage drop if using your method . If using the method in my previous post I would have more confidence of the residual capacity in the pack . Reading a voltage drop in my opinion isn't as informative as knowing the calculated mA capacity remaining based on previous useage data .