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Jun 25, 2017, 07:51 AM
jackerbes's Avatar
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Originally Posted by NKChea
Dear Jackerbes,

The current amps draw in your post is all about one motor or Total Amps in 4 props?
This is such kind of a stupid question, but I wondered.

And How can 3s li-po battery draw maximum Amps?
Can it feed 4 motors for 20A drawn battery?

In the last post, the one just above yours, I used the current draw I saw on one motor in static testing, multiplied it by four to get the total current draw of 8.2A for all four motors.

Things will always change a little in actual flight as the props can unload a little in flight and especially so when the quad is moving forward with some speed.

I don't understand your last question. A battery can satisfy a higher current draw but it generally needs to be larger to do that. In that example above where all four motors were drawing 8.2A if you changed that to 20A with the same battery the voltage would drop more and the capacity used up much more quickly. The flight duration would be less than half of what I estimated there, probably much less.

The size and quality of the battery is an important consideration. When battery sellers describe a battery as 20C or 30C they are saying that you can use a use a current draw that is 20 times or 30 times the battery's capacity. So a 20C 2000 mAh battery would, in theory, be OK at 20 x 2A or 40A. But we are relying on the honesty of the seller for that "20C" to be right. In most cases, you do not want to use a 20C battery at 20C continuously because it might cause the pack to get too hot. And when a pack get too hot is can suffer damage and lost some of it's capacity. Or in really bad cases, it can catch fire!

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Oct 07, 2017, 03:24 PM
Registered User
Hello All,
I make the first drone and bought the motor B2212_920 and frame F450. I have my own motor controller and I can adjust the RPM. I will use 4S LiPo. Today, for the first time, I switched on the motors and dispersed up to 7,000 RPM with the propeller (Gemfan 1045). After 2 minutes, the motor was very hot. It was impossible to touch. The current was 8A rms. With what RPM flying the drone ? On the Internet they write that the motor B2212 can operate 15-25A and peak current 30A. I hardly believe in it. The motor will overheat.

Thank you


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