snip

I had a look at the page and found a few odd things. The math for a motor
has not changed since they were invented. Only the efficiency in which they
convert input power to mechanical energy has improved.

Take a look at the 24 volt motor shown on:
http://www.electricmotorsport.com/PA...pecs.htm#Page5

Motor output is 15Hp max and 8 Hp continuous.

Well, this is *not* a 24V motor. It can be operated on 24VDC, but will
not reach its maximum rated output. It is a 50VDC motor, look at the
specifications box.

To get 15 Hp at 24 vdc assuming no losses, you would need 466.25 amps. The
motor is rated at a maximum motor current of 330 amps for 60 sec. You might
get the equivalent of 15 Hp for 5 seconds before it was toasted.

8 Hp would require 248.67 amps continuous at 24 vdc. brush life for that
current rating isn't given. What would it be? I don't know, maybe 24 hours
or less. It appears that brush life drops exponentially with current

Take another look at the page. The charts are for the same 50VDC motor
operated at three different voltages. The charts basically give you the
performance characteristics at the stated voltage - you can't
extrapolate from them.

The chart looks correct as it takes into account the losses in motor
efficiency. But the chart does not jive with the text below it. Notice the
chart only shows up to a tad over 4 Hp for a motor that the text below the
chart clearly states 15 Hp max, 8 Hp continuous.


The motor is rated for 150A continous. At 48VDC, that's 8HP at about
3100 RPM. That 150A continuous input would net you 4HP at about 1350
RPM. Half the voltage, half the VA, half the horsepower.

The 48 vdc motor is similar. A claimed maximum Hp of 15 Hp which would
require only 233 amps within the stated rating of the current limit for the
motor but think about the brush life, it is off the chart. When you look at
the chart, again it appears that brush life drops exponentially with
current.

8 Hp would require 124.3 amps. Still lots of amps.

Per the chart, it requires 150A. You're right, that's a lot!

Keith Hughes