Re: (ET) motor current

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

The motor is rated 3/4 hp at 36V.  Even on a full charge of 39+V, the
droop due to leads will be about 36V.  That's the max power under load,
not the free spinning power rating.

Larry Elie


-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Michael S
Briggs
Sent: Wednesday, July 26, 2006 6:02 PM
To: Neil Dennis
Cc: Elec-trak cosmos phy tufts edu
Subject: Re: (ET) motor current



On Wed, 26 Jul 2006, Neil Dennis wrote:

> First, if you have an accurate voltmeter / ohmmeter, measure the
voltage
> drop along the power lead, check the resistance - that should give you
a
> bllpark reading for the motor current.

D'oh! Good idea, I should have thought of that - essentially use the
lead 
for the motor as a shunt. *smack* (sound of me smacking myself in the 
forehead)

> Do that before you try the 10
> amp meter.  I'd guess that the motor draws more than 10 amps but maybe
> not.  Wonder, aren't they rated about 1 1/2 hp, that's about 1100
watts
> so go from there.

Damn, that's 28 Amps, assuming 39 volts. They presumably don't always
pull 
that much power, only when initialy starting up, and as needed to
maintain 
speed while cutting. Still, that initial startup would likely just blow 
the ammeter fuse. I'll use the lead as a shunt.

> Have you taken the motor apart, maybe the field magnet is cracked,
that
> could cause the problem.

Nope, haven't taken it apart. I figured I'd first see if I can find some

other problem causing it before disassembling the motor.
        If that is the problem - do the large diameter and small
diameter 
motors use the same field magnets? (I have a spare small motor, but the 
three I'm using are large ones) If not, perhaps some place has
replacement 
magnets?

Thanks
Mike

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