spec: When powering the brushless motors (rated from 6 to 12 cell) from a 8 cell battery pack it can achieve higher RPMs and generate more thust allowing it to carry heavier payload. So the idea is not really to increase the endurance, in which case running two packs in parallel would for sure make more sense. Its one battery pack with 8 identical cells connected in series.
For more information:
Not the battery I am using but very similar:
http://www.hobbyking.com/hobbyking/...ght_8S_12000mAh_2C_Multi_Rotor_Lipo_Pack.html
The motors:
http://www.rctigermotor.com/html/2014/Efficiency-Type_0314/198.html
@KISS: Thanks for the reference to tl494, I will study the datasheet tonight. Regarding your previous question. The autopilot needs 6 cell (max), the motors I want to power from 8 cells. But since I am not using 2 battery packs and only 1x 8 cell pack I need a way to provide the autopilot with between a 3 and 6 cell voltage levels.
les: Thanks, I now have a better understanding, this also seems like it could work. At the moment I am still looking at a more generic solution. Say I wanted to quickly change the failsafe threshold for some reason (doing longer flights and need the trigger earlier to have enough capacity to fly home, etc.). This is still a valid option though.
I have attached a basic picture to explain the situation. It only shows the power connection, between the autopilot and motor there is obviously control lines.
View attachment 97380