Please post your flight time with bigger, standard, or self-built batteries.

[VCD]

I can consistently get 22m (with gimbal and gopro) using 4S3P Li-ION made of
Samsung INR30Q
Sanyo 18650GA
I suspect adding 4 more cells would help by reducing the load per cell.

20min of so with Tattu 5200mAh

Did anyone try 7-9Ah packs?

 

[makatanav]

adding 4 more cells, will add extra weight and result not in so much time increase

 

[VCD]

you may be right, I do not remember the result, but there was a good amount of unused energy left when the cells reached the lowest voltage I aimed at, and reducing the current per cell might enable the use of that. - it's just a thought unless somebody has some data on that.

 

[makatanav]

you can read through this thread, there was plenty of information - 3DR Solo with LiIon 9000mAh battery | up to 30min flight time

from the thread: "So for 10% more weight the Solo consumes 16% more energy"