Dc Motor Question

[rsbmg]

I have a 1 horsepower 12v DC air compressor I plan on installing in my truck. Now a simple calculation says it draws 62 amps but others who have installed this motor are telling me that they have measured the amp draw and it never see's above 38 amps even at start-up or before shut doen. Can someone explain to me how this is possible and what I need to account for in calculating the draw? Obviously I'm, missing something.

Thanks for the help

Rob

 

[broadgage]

The one horsepower claimed may be a marketing claim, rather than actual genuine HP.
Alternatively, the unit may be capable of one HP but is not fully loaded, and therefore draws less current than expected.

Remember that 1 HP = 746 watts, but that the HP refers to the mechanical output of which the motor is allegedly capable, therefore the electrical input will be more than 746 watts.
850 watts might be reasonable as an input, that is about 80 amps input at 12 volts, IF it really is a true 1HP motor.

Much more likely to be a marketing claim though ! esp if someone has measured a current draw of 38 amps maximum.
Does the unit come with instructions ? If so what size fuse do they recomend ?

 

[sgunsel]

My shop vac is labeled in large letters "6.0 HP". Obviously not. HP claims on anything consumer related seem to be pure fantasy. If you believe the 38 amp figure, use that. Since you have the compressor, and presumably a 12 VDC battery in your truck, why not measure it yourself? Don't forget that voltage drop may be excessive, depending on distance between the battery and compressor.

 

[Besoeker]

I have a 1 horsepower 12v DC air compressor I plan on installing in my truck. Now a simple calculation says it draws 62 amps but others who have installed this motor are telling me that they have measured the amp draw and it never see's above 38 amps even at start-up or before shut doen. Can someone explain to me how this is possible and what I need to account for in calculating the draw? Obviously I'm, missing something.

Thanks for the help

Rob

Maybe the compressor needs less than 1HP to run it thus the current is lower than 62A?

 

[charlie b]

Forum rules do not allow us to provide assistance to a DIY. I am therefore closing this thread.