# Size of motor vs. amps



## major (Apr 4, 2008)

adric22 said:


> Will increasing the size of the motor give you more power? Or will it only help if you also give it more amps? In other words, if you give a big motor and a small motor the same number of volts and amps, will the resulting torque be the same?
> 
> 
> > Hi adric22,
> ...


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## roguesoul (May 3, 2008)

Compare Netgain's WarP 8" and 11". The answer , same horse power double the torque. Better efficiency too.

I refer you to their data. Look at the last line of numbers.
http://www.go-ev.com/images/003_12_WarP_8_SpreadSheet.jpg
http://www.go-ev.com/images/003_20_WarP_11_SpreadSheet.jpg




adric22 said:


> Will increasing the size of the motor give you more power? Or will it only help if you also give it more amps? In other words, if you give a big motor and a small motor the same number of volts and amps, will the resulting torque be the same?


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## TheSGC (Nov 15, 2007)

Just my $0.02, but changing the motor to a larger size and NOT increasing the system voltage will probably lead to higher AMP draw and less range. Bigger motor needs more AMPs to move it.

I think in your case it might be better to increase the voltage to something like 84 volts or 96 volts and see what happens withe ES-15A. Apparently it can take up to 120 volts, so 84 or 96 should be fine. It would mean less AMP draw for the same HP needed to move the car. AMPS = HEAT

My original EV plans were for a 72 volt system and a 10HP motor, but the AMP draw would be 104 AMPs for the 10 HP continuous. I then changed my design to a 96 volt system and a 96 volt 10 HP motor and the estiamted AMP draw for 10 HP is only 78 AMPs. 25% decrease in AMPs means a lot less heat, longer duty cycles and I plan on cooling the motor with some fan cooling. Now I only designed my EV for 45 MPH and less speeds.


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