selection criteria for controller !

[himanshu]

hello....i am building an electric kart !
i am using a 800 watt PMDC motor

Power Consumption : 48V
Current Usage : 42 Ah
RPM : 3600
Maximum Torque : 12.8 Nm @2400 RPM

there are 4 new lithium ion batteries 12V each in the kart !

i am confused with the selection of controller ! :/
minimum speed should be 30 km/hr
plz help!
and thanx in advance !

 

[dcastillo]

Doing the math, that's only about 16amp, maybe more for the take off, i would get a controller that can do a continuous 30amps minimum. Should only cost you about 75 bucks....

 

[itsid]

^^ What he said
Well, 25Amps would do I guess, but I doubt there is a 25A controller that's reasonably cheaper than a 30A controller at all, so yes 30A is perfect for a motor with that Amperage.

Even the target speed of 30km/h will be within reach,
based on the torque curve of the motor (Nm per rpm) and assuming you mount 11" dia wheels,
with a 6:1 ratio you'll end up with 33km/h.

6:1 because you have about the same torque as a standard 6.5HP [clone-] engine,
so it's std. gear ratio should work perfectly.

'sid

 

[himanshu]

yup the dia of the rim of the wheel is about 10" so overall it would be like 12".
can you tell that how much speed that i expect from this motor if i increase the gear ratio and with 170 kgs of weight including the driver......i know it is kind of hypothetical coz it depends on various factors.......but still an estimate would do the trick

 

[itsid]

Honestly? No, I can't
If I had to make an assumption I'd say you might get away with a 5.5 or even 5:1 ratio on flat terrain.
But I wouldn't take any bets

'sid