I have the 3DR quad frame with standard motors and wondering if I can use a 1800mAh Turnigy 30-40C 3cell. I know it would decrease the flight time but just wondering if there is any problem otherwise in using a smaller battery. Didn't want to start a fire :)
I normally use 3000 or 5000mAh but am having some dead cell issues with them now but have some new 1800 I would like to try.
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Also tried a nano-tech 5000 4S and got 20 minutes with gps, mag, xbee, sonar and lights. It flew a bit heavy but didn't seem to bother it.
I'm curious if there is any advantage of using a 4S over a 3S. Since the motors rpm is directly related to voltage, there would be a longer flight time on a 5000 4S compared to a 5000maH 3S and of course it's heavier.
I'm just not sure I'm understanding it correctly. They both have 5000mAh. If I use less throttle stick when using the 4S because of it's higher voltage then I'm going to use mA more slowly correct?
Is there some other advantage to going with a 4S? Does increasing voltage increase efficiency in some way?
I tried the 1800mAh 30C and got about 6 minutes of flight with sonar and gps and about 48 strong LEDs. 12 per leg.
I also have a 4S 5000mAh nanotech turnigy. Any problem trying that, as long as I don't max out the throttle??
First you need to know the total maximum current draw from your copter. Assuming its a stock Arducopter Quad, lets *GUESS* 42 amps(I think a purple Jani motor tops out at 9 amps each).
Now. Take the capacity of your battery pack and Multiply it by the constant C rating (not the surge rating thats only good for a short time not a whole flight). That gives you the max power the battery can safely provide. So, a 1.8 (1800 mah) battery * 30c = 54 amps or 1.8 * 40c = 72 amps. You should be fine with either but 40c increases safe margin considerably.
Numbers above are an example! You need to know your quads max current draw. Or at least estimate it from motor data sheets and current draw of other connected equipmemt.