Dji 550 lipo question

[ponchota]

Building a DJI550 clone 10" props, with kk2.0. DJI 2212 motors and HKF30 30amp esc w/simonk firmware.
My question is... I'm am def. using a 3s lipo in the 4000-5000mah range for more time in the air, but what C rating. Will 20c suffice? What will be the cons of not using a higher C rating? Also why 3s with 10" props and 4s for 8"props.

Thanks

 

[Electro 2]

"what C rating. Will 20c suffice?"
As high as possible if the ratings are actually accurate, with many manufacturers, this isn't true. Fly for a minute, drop it, check battery temperature, if OK, rock on.

"Also why 3s with 10" props and 4s for 8"props."
For a given Kv, higher voltage = higher speed + smaller prop area = same thrust. (Up to a point)

 

[ponchota]

But with a larger prop = more resistance so wouldn't the 4s = more voltage be a better fit for 10" props?

I know C is discharge rate but I was hoping for a better explanation.

 

[rwskier]

http://www.rchelicopterfun.com/rc-lipo-batteries.html

this should help you.