RE: (ET) More lift motor thoughts

["Elie, Larry \(L.D.\)" <lelie ford com>]

I think your rear is on the wrong taps.  They should BOTH be run off 
"18V".  
Getting the taps wrong is REAL common.  Even though I can count batteries, 
checking 
with a volt meter saves some work and money later.  The motor will run on 
24V... for 
about 3 up and down cycles...then the insulation melts.

In addition; GE did NOT re-wind the motor; it's a standard "12V" 
automotive motor.  
They knew the duty cycle, which is part of what governs the winding 
temperature, 
would be short.  This is not unique.  The starter motor in your car would 
melt if 
you ran it at the nominal 12-14V for say 1/2 hour.  The torque on a motor 
is proportional 
to the current in the windings times the number of winds.  The torque does 
not 
know anything about voltage, BUT; the to get the current up requires 
voltage.  To get 
the current REAL high requires MORE voltage.  That's when ohmic losses 
come and carry 
you away; voltage=current times resistance.  To get more windings you use 
small gauge 
wire, which is higher resistance.  In addition, the wire resistance 
increases with 
temperature.  This is something every motor designer deals with.  So if a 
motor is not 
expected to see continuous duty; the lift motor or a starter motor, you 
just design for 
that case and hope no one tries to run it too long.

Larry Elie



-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu]On Behalf Of Chris Zach
Sent: Monday, April 18, 2005 7:32 PM
To: Elec-trak list
Subject: (ET) More lift motor thoughts


Checking this motor against the front one, I notice they seem to run at 
about the same speed, and sound about the same. Front is on 18 volts, 
rear is 12.

I'm not sure about the power, but I'm wondering if GE went with 18 volt 
windings to combat voltage drop or something. That said, it seems to 
work fine. Will try it with the tiller next weekend.

Chris


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