watts vs watts
 

what I’m talking about is electrical watts vs mechanical watts.
e.g. I have a 1930/8 brushless motor and its rated at 1200watts now would that be the electrical power it draws volts x amps? Or output mechanical torque?

this is the 1930/8 turn motor:
http://www.finedesignrc.com/lehnerspecs.htm

It says "Power(Watts) @ Amps"

btw what’s the efficiency of the 1930/8

I believe thats the watts its capable of pulling from the batteries. The power output would be about the same as well. Don't quote me on it though...

They can pull alot more than that though,basic Xls have measured a couple of KW and they're only rated for 1300w,something like that.

I think of them as a sort of a guideline,kind of that's what the motor is rated to do without being overworked.

Don't pay attention to those ratings. They don't really mean anything. The power output mostly depends on your batteries and your gearing.

You can't equate torque with power. Watts is convertable to horsepower. IIRC, you can however calculate torque by using rpm and horsepower.

Oh, and the effiency of these motors depends on load and voltage. But you can see some graphs and data on this page.

14.8v lipo, MGM 16016-3, 1930/8 I don’t know the gearing yet all I want to know is the power of the motor without load, just a rough estimate with out measuring it properly because a lot of people are asking and I don’t really know how much power it has. Watts / horsepower something like that.

I think its roughly a little less than 2 HP. Around 1.75 HP.

Hi,

Just as a comparision, I was able to draw 84.2A X 13.1V = 1103.02W from my setup using a feigao 7XL & 4S 20C lipo during hard acceleration. This was measured using an Eagletree data logging thingy. Of course, the power available at the wheel will be less due to losses in the form of heat etc.

Regards,
Joe Ling

Wouldn’t the power at the wheels be greater and the rpm less due to gearing?

The power at the wheels is less (don't confuse power with torque, the torque at the wheels is greater because of reduced RPM). You can never have as much output power as input power unless there is 100% efficiency. In the case of our RC vehicles (as well as real vehicles) there is mechanical efficiency as well, determined by the drivetrain and weight.