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Re: (ET) Power of Elec-trak motors?
Marcus wrote:
These ratings are correct if they came from GE. You won't be able to
check by reading the amps. Remember an electric motor can put out far
above it's "rated" capacity but not for long. It's all about heat. A
motor's continuous rating is the output it can safely sustain without
overheating. Some motors are rated "intermittent" with a certain duty
cycle and some "continuous" Many scooter motors especially from China
are vastly over rated. A real 1 hp continuous permanent magnet motor
should be about 14" x 5.5" and weigh a ton. The E12 has a motor about
this size. A wound motor of the same rating will have a larger diameter.
(E 15)
Ok. Well, I just hopped in the E20 this afternoon and drove across my
front lawn in speed 4, gear L, deck on the mower, deck motors *off*.
Current draw on my two strings of BB600's was 15a and 25a. Voltage was
right around 36v.
So it appears that *my* E20 takes 40a to drive along doing nothing else
(overcoming friction, gear resistance, and moving it's arguably lighter
self). Now my E20 is lighter than most, each BB600 cell weighs 3.2
pounds so 90 of them weigh only 288lbs. By comparison a Trojan T105
weighs in at 61 pounds, so six of them weigh 366 pounds.
Given that, the question is what is the motor efficiency under normal
load? If it was 100% then the motor is taking in 1.88hp just to move the
tractor. I would think that GE would consider "drive the tractor on
level ground" to be the absolute minimum so the motor should be a bit
bigger than 1hp.
I guess one could test by putting the motor on a bench, attaching it to
some sort of constant load, and driving it till it got above normal
operating temps. Then write down the amount of current it is taking and
you have the HP ratings.
Do some good research before deciding on a motor and avoid letting the
smoke out of your first attempt. There are threads about converting a
gas mower on ecomodder.com and examples at EV discussion forums if you
do a search.
Absolutely. Experience seems to show that a good golf-cart motor should
be enough to run a normal tractor+blades. So put one in and see how it
works.
Chris