(ET) Debugging ET 12S (was Power Disconnect for an E12M)

["Darryl McMahon" <darryl econogics com>]

Dave, WHOA!!!!
> I should be starting a new thread here but don't know how.  maybe someone
> could enlighten me.

Just change the subject line in your reply message.

> 
> Anyway my friends and I were debugging my newly acquired E12S (it doesn't
> move).  After cleaning all the battery terminals and various other
> connections and dropping the motor to the ground we finally got the motor
> to spin but always in the same direction, reverse.  Swapping the field
> wires at the motor didn't make any difference.  This was really 
> puzzling. 
> Then we pulled the field wires off altogether and lo and behold the motor
> turned still in reverse.  Tracing the wires we discovered one of the 
> wires
> from the siamesed relays (installed by the previous owner to  simulate 
> the
> original reversing relay) had at some previous time taken enough current
> to burn the little jumper between pins inside a connector further down 
> the
> harness.  Bypassing the burnt out connector and removing the siamesed
> relays we got voltage to the field and then reversing the field wires had
> the expected and desired result of turning the motor in opposite
> directions.  My friend Craig has found a double pole double throw relay 
> in
> the Hosfelt catalog that appears to have adequate specs  10amp at 30volts
> but for the ridiculously low price of $1.49!  I wonder if it is advisable
> to use it?

On the E12 series, I believe the motors have permanent magnet 
fields.  There are NO field wires!  On my E12S, there are 6 wires to 
the motor.  The 2 heavy leads are the armature power leads.  The 
four lighter wires are for a centrifugal switch interlock cutout, and a 
thermal switch cutout.  These act in the same manner as the brake 
switch cutout and seat switch cutout.  These wires do not carry 
significant power, just solenoid control power.  This is why the 
motor will turn the same way if the "field" leads are reversed, or 
disconnnected.

If you do not have an owner's service manual, please get one.  (Bill 
Gunn at Technical Service & Parts (608-868-6228).  You need the 
schematics for this level of debugging.

If you have the manual, start following the wires in there.

To change the direction of rotation, you have to change the 
connection of the armature leads.  This is normally done via the 
contactors under the dash, and controlled by the speed/direction 
controller stick.  Perhaps something in the maze of wires between 
the solenoids and control switches is reversed, or one of the 
solenoid contactors is welded.

Disconnect the armature leads at the bottom of the controller area, 
then apply power to the leads directly.  Check direction of rotation.  
Reverse the connections.  Check direction of rotation.  I suspect it 
will be reversed.  Then you can continue your debugging of the 
wiring from there.


> 
> I see the original relay/contactor is rated at 36v but no amp rating.  It
> is fried and I don't know for sure how it got that way but suspect the
> cable under the tractor that had its insulation ground off when it
> evidently came in contact with the pulley at sometime might have 
> something
> to do with it.  It says Technical Services on the coil inside the relay. 
> Can someone give me an idea what this relay costs?

Call Bill (see number above).
> 

Darryl McMahon             http://www.econogics.com
1973 Elec-Trak E12 electric tractor
1974 Auranthetic Charger electric motorcycle
1975 EVA Metro (Renault 12 conversion) electric car
1986 Pontiac Fiero (conversion) electric car
1997 SpinCraft Explorer electric boat
current project - B&D Model 8080 electric reel mower
next project - 1973 Porsche 914 conversion
"The Internal Combustion Engine, it's so 20th century."