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Go Kart Top Speed Calculus
#1
I am getting different numbers when I run the following top speed calculation. Can you help? Assume the following.

Go Kart weight with batteries, motor drive system and driver: 400 pounds total weight.
Rear Wheels: 6 inch diameter (Rear Tires are Maxxis “Pink” with a 12” diameter)

Motor: AC-9 48V
Controller: 48V 600A Curtis 1236SE-5621

Running 600 amps (max) on level payment in 70 degrees Fahrenheit, what do you think my top speed would be with a sprocket ratio of 4-to-1. Thanks.

VenomKarts, LLC
VenomKarts.com
Augusta, GA
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#2
On level ground with 600A at 48V this is 28kW so enough in theory to push it to something like 50mph or more
With 1500rpm you will only be going 21kph / 13.4mph so your motor would need to be doing 5,000rpm to get to 44.7mph.

Would have thought it would depends on what rpm the motor can do.... efficienctly.... the motor may be able to do 8000rpm but it may be at a very low efficiency and output.

For the motor you should have a power/efficiency curve and this will show what your limiting factors will be.

Also ... Higher top speed == less acceleration
garolittle likes this post
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#3
Thanks. That’s good information. I really appreciate the response.
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#4
I tried running the numbers as I would for a car from a mechanical standpoint using a calculator on the web at http://www.wallaceracing.com/gear-speed.php

I used 6 as the tire diameter, 1 for the transmission gear and 4 for gear 1. The calculator will return a table with RPM and ground speed in mph assuming no losses . Pretty simple, but may help you confirm a theoretical top speed based on your mechanical specs.

That would assume the motor has the power to accelerate the weight and continue to rev up to a specific RPM.
Regards,
Gary G.

Working on a 32 port #FCDS
24 ports complete... logging to Influx/Grafana

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#5
(02-13-2019, 11:21 PM)SecondHandPower Wrote: I tried running the numbers as I would for a car from a mechanical standpoint using a calculator on the web at http://www.wallaceracing.com/gear-speed.php

I used 6 as the tire diameter, 1 for the transmission gear and 4 for gear 1. The calculator will return a table with RPM and ground speed in mph assuming no losses . Pretty simple, but may help you confirm a theoretical top speed based on your mechanical specs.

That would assume the motor has the power to accelerate the weight and continue to rev up to a specific RPM.
Really appreciate the response. This is good information. Thanks.
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