motor too powerful?

[gary]

42VOLT DC
5.9KW
15MINS RATEING
3300RPM
WDG SERIES
CLASS F

Looking to make a go kart that goes about 30-50mph

Would the above motor be okay?
could i power on 3 12v car batteries?

Thanks

 

[Skalabala]

Sounds awesome to me! But you will need to invest in good batteries like golf cart ones.
And get cooling of some sort for the motor
And if you run it at 36v it will not heat up that much but you will also not get its peak power.

 

[gary]

Sounds awesome to me! But you will need to invest in good batteries like golf cart ones.
And get cooling of some sort for the motor
And if you run it at 36v it will not heat up that much but you will also not get its peak power.

Thanks, i am considering 4 now and after calculating the amps it would use im going to need some good batteries like you said

i think, 4 x 12 = 48v
5900/48 = 123A
So to last an hour im going to need 4 130Ah batteries? or would it be 4 (130Ah/4 = 32.5Ah) batteries?

Last time i looked, theyre about £100 each

Also, i would need a very good PWM which are very costly so i was thinking of making my own considering i am training to be an electronics engineer, does anyone have any schematics for one that works well?

 

[r_chez_08]

That would be one helluva kart! If you can afford the batteries and controller that would be sweet. (Hate to tell you, a gas kart would be cheaper!)

 

[gary]

That would be one helluva kart! If you can afford the batteries and controller that would be sweet. (Hate to tell you, a gas kart would be cheaper!)

thanks for response, how much out of curiosity would a gas kart be about the same power?

 

[r_chez_08]

Depends on the engine. I would have thought that the above motor would provide a similar driving experience to a smaller bike engine.

 

[GregMartin]

And if you run it at 36v it will not heat up that much but you will also not get its peak power.

OK remember that power = volts by current in its simplest from. So the impedance of the motor is constant so it can't change and the voltage is constant more or less. The electric motor will try to make full rated power and to do this it will pull more current. Current results in heat and this in turn will short the winding of you motor I.e. burn it out. So 48V would be better than 36V. You can source led acid gel batteries that have low internal resistance so can produce very high cranking amps. They are available in various voltages, they are relatively small and don't spill because they are gel filled, however they are expensive.

Those kind of batteries are used in the electricity industry for control of remote high voltage switches and also in telecommunications exchanges so you by be able to pick them up from auction. If they are bulging they are stuffed. If they are sucked in they are good.

Good luck

 

[Skalabala]

You will have theoretical 123A draw yes. But that is at full load.
Heat, efficiency all play a role. If you could drive it for 20min at 123A load then you must be a happy person Sitting in a cart for more than 20min is not nice on your body
And make your own controller!
There are some nice DIY PWM diagrams on the net, just need to dig deep.

 

[GregMartin]

It's a long time since I did machine theory at uni so I would have to look up the heat loadings and thus how long the motor can stand the over load. Also the variable speed drive will have some affect. But in reality you would never start with under voltage if you want efficient motor output.

My kids give their go kart a good couple of hours but of course it's a petrol number