Howdy,
Most (small) DC motors will rotate at ~70 - 100 rpms (revolutions per minute) per volt of input.
so, I'll use 85 (kinda in the middle) for this example
a 12V motor will rotate at ~1,020 RPM's (12V x 85 = 1,020 RPM's)
If you supply it
...24V it should rotate at ~ 2,040 RPM's
...36V = 3,060 RPM's
...& @ 48V = 4,080 RPM's
Once you have an idea of the motors RPM"s, there are (3) main variables to figuring out how fast a (given) motor will propel your car/kart
1.) Motor RPM's
2.) Gear Ratio
3.) Tire Circumference
By inputting your
...motor RPM's
...gear ratio
...& your tire circumference
in to this equation, you can figure out what your, potential, MPH would/could be
MS/GR=ASxTC=IM/FT=FMxHR=FHxMM= MPH
Motor Speed/Gear Ratio=Axle Speed x Tire Circumference = Inches per Minute traveled/Foot(12) = Feet per Minute traveled x Hour(60) = Feet per Hour traveled x MPH Multiplier(.000189) = Miles Per Hour
* Using e-Lemon-aid, as an example
[email protected] 24V (@ 2,000 RPM's) (Rated at 2,500 RPM's max)
...an 8:1 gear ratio
...& tires with ~38" circumference
2,000/8 = 250
250x38" = 9,500"
9,500"/12 = 791.67'
791.67x60 = 47,500
47,500x.000189 = 8.98 MPH
Motor speed is (2,000 rpm's) divided by the gear ratio (8) = axle speed (250)
Axle speed (250) times the wheel circumference (38") = inches per minute traveled (9,500")
Inches per minute traveled (9,500") divided by inches in a foot (12") = Feet per minute traveled (791.67)
Feet per minute traveled (791.67) times minutes in an hour (60) = feet per hour traveled (47,500)
Feet per hour traveled times miles per hour multiplier (.000189) = 8.98 MPH
Yup, according to the GPS she topped out at ~9 MPH
https://www.youtube.com/watch?v=uBT9B0sqNe4
Using it helps me to determine the potential speed of a vehicle (motor gear ratio & wheel size)
...it does NOT take into account wind resistance, rolling resistance, total weight & many other factors
...but, It'll at least gives me a rough idea or put's me "in the ball park".