I've been doing test flights with my quad for a couple weeks now using 3S 2200mAh 20C batteries. Admittedly the first few flights I was running the battery down to the point it wouldn't lift off the ground anymore (about 10 minutes of messing around) and then using a balancing charger to charge them back up, but now I've been reading about the do's and don'ts of LiPo packs.
I think my quad is on the heavy side, I haven't weighed it, but it's arms are made of slightly thicker aluminum than the 3DR ones and my legs are garolite, but slightly bigger also. The rest of it is mostly 3DR stuff, the motors, ESCs, APM 2.5, and so on. So after reading this article I decided to solder the voltage leads of my Spektrum telemetry module to the battery input wires of my power dist. board and watch what my battery was doing, I set the alarm on my DX8 for 11.2 volts (based on that article I linked to) and much to my surprise it only took 3 minutes of flying for the alarm to go off.
In 3 minutes I was going from 12.6 to 11.2 volts under load in the air and it would creep back up around 11.8 if I landed and let it sit a minute but not 30 seconds later after going back up in the air it would dip below 11.2 again.
So here's my question, if LiPo batteries aren't supposed to be run down past 3.7v per cell regularly, why do all the fixed battery alarms not go off until 3.3v? Also my DX8 default alarm parameters was something like 9.8v when I selected 3S. When I do run my batteries down to the 3.3v/cell range, they take 60-65 minutes to charge and balance at 1C (2200mAh) and when I stop at a load voltage of 11.2 and balance one, it only takes about 20 minutes to charge and balance because it's starting out around 3.8v/cell unloaded. Do I need to disregard the 3.7v/cell thing and run them down to 3.3 and get my 10 minutes of flight and 1 hour charge time, or do I deal with 3 minutes run times until I lose weight or get bigger batteries?