Is there a accurate way to calculate Horse Power on rc motors?

[#ARRMArcfanboy4life]

Is there some formula or link I could use to calculate the horse power of my brushless motors?

 

[KiTris ExtremeRC]

Is there some formula or link I could use to calculate the horse power of my brushless motors?

If you know the amps and voltage that went through the motor you can calculate the power in watts. And watts times 0.00136 is the power in hp. Usually our brushless motors have an efficiency of around 85-90%. So the formula would be: volts * amps * efficiency_factor * 0.00136
A Castle ESC with data-logging will show the power output, without the efficiency factor

 

[Mazin]

Edited: 746 not 1800 watts is 1hp
You can put a watt meter in series between the battery and esc and find out

 

[HZRDOS]

Just use this formula, very easy:

 

[LibertyMKiii]

You would have to know your voltage and amperage to get watts. Once you know watts you can find the HP
I just round up and say 746 watts = 1 hp.
Then of course take total watts times 0.9 to take into account that 10% of power is lost to efficiency and heat.

 

[Mazin]

You would have to know your voltage and amperage to get watts. Once you know watts you can find the HP
I just round up and say 746 watts = 1 hp.
Then of course take total watts times 0.9 to take into account that 10% of power is lost to efficiency and heat.

View attachment 185804

Yup 746, 1800 was my Bi Plane I just built.....sorry its still early

 

[Starfox2005]

Is there some formula or link I could use to calculate the horse power of my brushless motors?

If you do figure out how to find HP I'd like to know what the stock blx 6s power system makes.
What about using the Max ESC drawing amperage?

 

[LibertyMKiii]

If you do figure out how to find HP I'd like to know what the stock blx 6s power system makes.
What about using the Max ESC drawing amperage?

We would have to assume many things.

Lets assume that your fully charged 6s lipo sags to 19v under 150amp load.
Lets assume that the hobby wing ESC is limited to 150 amps.

19v * 150a = 2850 watts.

less 10% for efficiency losses. 2850 * 0.9 = 2565 watts.

2565 watts converted to hp (746 watts = 1 hp) = 3.43 hp

 

[Starfox2005]

How would you do that more accurately? You would have to load the motor some way other than running the vehicle and so the data might not be accurate? Maybe I've just got it all wrong?

 

[LibertyMKiii]

How would you do that more accurately? You would have to load the motor some way other than running the vehicle and so the data might not be accurate? Maybe I've just got it all wrong?

There could be ways to test it bust honestly you would spend alot of money and time doing so.
The easy way..... You could run a Castle MMX8s, MMX6s, or XLX2 esc that has data logging and know exactly what the wattage output of the ESC is.

 

[jkflow]

For true 'rubber meets the road' power you have to use a dyno. Else you have to assume losses as per above.
Easy to calculate power the Lipo provides, everything else has mechanical losses, which can be estimated but not measured.

 

[LibertyMKiii]

For true 'rubber meets the road' power you have to use a dyno. Else you have to assume losses as per above.
Easy to calculate power the Lipo provides, everything else has mechanical losses, which can be estimated but not measured.

And to expand on this further rolling road dynos often have issues with tires slipping. I can only imagine this would be worse with an RC car.
To resolve this higher hp dynos utilize a bolt on hub adapter.

Example from our local HP master T1 Racing who is one of the worlds best tuners: