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If a motor has more Power (W) from another it means that it is better?

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  • $\begingroup$ It is better if you need more Power. It is worse if you don't need more power and it uses your fuel source up too fast. $\endgroup$ – medivh Jun 24 '13 at 12:59
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The short answer is no. The longer answer requires more information from you, regarding how the motor is to be used.

Since you have tagged your question with "quadcopter", I'm going to assume that you plan to put the motor on a UAV, in which case more power definitely does not mean "better".

More power (W) will draw more current (A) from the battery (meaning a larger battery and higher all-up-weight (AUW) of the craft).

You need to choose the correct motor and prop for your particular quadcopter frame. There is no one-size-fits-all motor for quadcopters. In general, you should be looking for a brushless outrunner motor with low kv, and pairing it with a slow-fly prop.

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  • $\begingroup$ why low kv? and what is a slow-fly? thanks. btw +1 for noticing the quadcopter tag ;) $\endgroup$ – Dan Barzilay Jun 24 '13 at 9:13
  • $\begingroup$ i believe that you typically want a relatively high KV for a multi rotor vehicle. $\endgroup$ – Octopus Jun 24 '13 at 21:09
  • $\begingroup$ No, you want to use low kv motors for a multicopter, paired with long diameter, slow-fly propellers. The reason being that it is more efficient to generate thrust using long propellers rotating slowly than it is to use short propellers rotating quickly. Slow-fly propellers are used because they generate static thrust (used in hovering) more efficiently than propellers designed for high-speed aircraft. $\endgroup$ – Jean-Baptiste Jun 25 '13 at 4:40
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The wattage rating is usually (read the manufacturer's specs very carefully) the measure of how much power the motor can draw. It doesn't tell you anything more than that.

Wattage does not tell you whether the motor is efficient at converting the input electrical energy into output mechanical energy.

Wattage does not tell you whether the motor's power-to-weight ratio is reasonable.

Wattage does not tell you whether the motor's size is reasonable for your application.

Wattage does not tell you whether the stall torque or maximum speed is correct for the load you wish to drive.

Wattage does not tell you whether the motor's duty cycle can support the needs of your application.

If you are comparing 2 motors that differ only by their input power rating, and more power is important to you, then yes: the motor with more power will be better for you.

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