CrashBurn69

My Feedback: (1)

When dealing with a KV rating, is a lower number more powerful or is a higher number better? Like a Park 370 4100 compared to a Park 370 5400KV. Thanks

nappyroots2182

My Feedback: (1)

when selecting the kv you should think of what battery you are going to use first. like if you are running a 2 cell lithium then youd usually go with a higher kv. and if you run 3 cell youd go with a lower kv. it all depends on how light you want your plane and your flying style you want.

CrashBurn69

My Feedback: (1)

Will a 3 cell work on the 5400 KV?

Matt Kirsch

My Feedback: (21)

Technically, neither is "more powerful" or "better." Kv numbers simply tell you how many RPMs the motor will spin per Volt of input power. The maximum current and voltage/cell count ratings are what tell you how powerful the motor COULD be, if you take advantage of it.

Given the same battery pack, the same gear ratio, and the same prop, the 5400 motor will "be more powerful." That is, it will spin the propeller at a higher RPM, generating more thrust and a higher forward speed for the airplane.

You can also adjust the gear ratio so the 5400 spins the same prop at the same RPM as the 4100. Then they're both equally "powerful." You could also adjust the propeller size so the 5400 draws the same Amps as the 4100. Again, they'd be equally "powerful." You can also put a bigger prop on the 4100 so it draws more Amps, and make it "more powerful" than the 5400.

If you poke around, you'll see many reports about Himaxx and Eflite Park 370 motors with fractured magnets. Many/most, if not all of these are the 5400 Kv versions, and many/most, if not all were being run on a 3S LiPoly. The no-load RPM of the 5400Kv motor on a freshly charged 3S LiPoly (12.6 Volts) is 68,040 RPM! Sixty-eight THOUSAND RPM, on a $50 motor. It's just not going to take it. We're talking jet turbine speeds. With a prop to load them down, they do run at a reasonable RPM, but people just can't resist revving the motor up that first time after the connections are made...

CrashBurn69

My Feedback: (1)

Thanks Matt, thats exactly the information I was looking for.

WM2H

Typically, motors with a lower kv rating have a higher torque than motors with a higher kv rating. A motor with a higher kv rating is more efficient at higher current levels than a motor with a lower kv rating. The least complicated reason being a higher kv motor has less turns - wire in the windings therefore less resistance. Like Matt said neither is " more powerfull " however each will be more efficient at a different current level for a given voltage. For example, if you reqire a power system to deliver 300 watts input power to the prop you could run a 3 lipo pack at about 27 amps ( 300/11.1 ) or you could run a 4 lipo pack at about 20 amps ( 300/14.8 ). After determining which battery system to use I would then choose a motor that has its maximum efficiency at either 20 or 27 amps at 14.8 or 11.1 volts then gear and prop it accordingly. Hypothetically, you would want to use the 5400kv motor with the 3 cell set up and the 4100 kv motor with the 4 cell set up. I would suggest that you try moto calc or similar program and experiment with different set ups until you find what you think is best for your application. This web site http://flydma.com/flydmahome.asp has a calc program on it that may help you as well.

S.