Direct Driving a DC motor to a Go Kart

[zuq]

Hey Guys

I have a question for mechanical guys...

I am converting a Go Kart from petrol to electric, If I couple my DC motor to the GO kart rear wheels via a chain (direct drive), would that create any problems?

I am confused because, the motor is rated to turn at high RPMS, how would that translate into speed for my wheels?? Would that just do a massive burn out because motor will be trying to spin at huge RPMS??

Cheers

 

[kak111]

Before this case can be evaluated we should know
Maximum power of the new motor , torque vs. RPM chart (type of motor)
Additional weight caused by the batteries
Rear wheel diameter

for reference:
power of the old motor
max. speed, acceleration (old)
brutto weight old system ( with driver)

 

[zuq]

Thanks kak,
The old motor is 6.5hp, the manual says tyre is 6", assuming thts the radius?Max speed 25mph (STC)
I need some help in choosing new motor, what should I consider? just pick a motor that will give right power or???

 

[kak111]

I think 6" is maybe rim size.
For calculating speed and torque we need to know rear tyre diameter.

If i guess tyre dia. is 10" then
10" ( 254mm) circumference is 0.80m

1000rpm 800m/min >> 48km/h
2000rpm 1600m/min>> 96km/h
4000rpm 3200m/min>>192km/h
6000rpm 4800m/min>>288km/h

so there must be drive ratio downwards a lot
if we take down 2:1 , we get double torque in back axle.

If old motor is 6.5hp >> 4.8kW
this means 24V motor and 200 Amps ( 48V 100Amps)

And with BLDC motor it means max. torque from zero rpm.

But where to find motor and controller for reasonable price.

Here is some ideas.....
from modified normal car alternator you can take out 1.2...5kW.....or more
Alternator Motor Update « Procrastinatus
DIY Hybrid Brushless Motor Controller (Using a car's alternator as a motor) - DIY Electric Car Forums
BLDC motor from an automotive alternator / Harjatontasavirtamoottori autonlaturista - YouTube

Electric gokart with 15 kW motor and 22AH LiPo Battery 50 volts makes 90Km/hrs.
EL go kart - YouTube
Close look on the electric gokart that beat 2 strokes
Close look on the electric gokart that beat 2 strokes - YouTube
40 HP Electric GoKart
40 HP Electric GoKart - YouTube

KAK