Re:(ET) shunt for Alltrax E15 retrofit - what specs,or how t

["CleanPower" <cleanpower att net>]

Hi,
 The late model tractors did not use a shunt plate. What they called a 
"shunt" was actually wire #2 running from the power disconnect switch to 
the PTO contactor. The Power Use Guage is then wired to those same 2 
terminals. Wire #2 is 18 - 1/4 " long made from 6 gauge wire and looks 
like many other wires used on the tractor. You should still have that wire 
intact if you retained the PTO circuit.
 Also,I would recommend not defeating the purpose of the thermal circuit 
breaker on the main motor. It was provided to protect your motor and that 
is still important,no matter what speed control you're using. Let it in 
line with the armature circuit where it belongs.
 If you need a wiring diagram for your E15HA I would be happy to fax it to 
you.
 Harold Zimmerman
717-859-4234 phone
717-859-4824 fax
--------------------------------------------------------------
My E15 (that I picked up off EBay last month with mower and snowblower)  
wouldn't move under its own power.  Opening up the control box, I found  a 
rat's nest.  Actually the previous owner said they were chipmunks, but  in 
any case it was a mess.  Lots of wires were chewed and corroded and I  
didn't know where to start.  Since it is a HA (relatively late-model),  
most of the diagrams I've been able to download didn't relate to my  
circuit with 5 contactors and different control logic.  Somebody's  
website I saw mentioned a conversion using a Curtis 1204 or some such  
controller, and I decided new technology was the way to go.  Luckily  
(since I'm not an electrical engineer) before I ordered one of those I  
found this list and discovered the Alltrax controller.  I ordered it  last 
week and started the installation.

I'm nearly done but I've hit a couple of snags.  Steve Richardson at  
Alltrax answered my questions about the external resistor (1 W 10 Ohm)  
and diode (3A 100V) shown on their schematic - it turns out I need to  
obtain those myself.  

But the big problem is that my original circuit didn't have a shunt, at  
least not one I recognized as such.  And if it was just a length of wire  
like Steve said he saw on a E20, then I have no idea which wire it was.   
Evparts.com lists a pretty good selection of shunts 
(http://www.evparts.com/shopping/?id=943) under the Renewable section,  
but I don't know which one to get to match the ammeter in the E15. 

Also, I re-used one of the leftover open-frame relays to implement  
key-switch and seat-switch interruption of the PTO contactor, a feature  
originally present in my machine and not shown on the Alltrax schematic. 
 Since I have an almost 3-year old around, I thought the safety feature  
was worth an extra 1/2 hour of crimping and locating the right  
interconnections to use.

Steve suggested that the thermal cut-out switch mounted on the drive  
motor could be rewired in series with the key-switch and seat-switch,  
rather than in series with the M- lead, this would serve the same effect  
and reduce the current carried by the thermal cut-out and thus any  arcing 
if the cut-out opens.  Using a 18-gauge wire would simplify  rewiring for 
anyone who's removed the chassis wiring.  I guess if I do  this I'll add 
an override switch so I can debug which switch is failing  (key, seat, or 
thermal cut-out).

Questions:
Should I get an off-the-shelf shunt for this meter?  Or if I'm better  off 
solving my problem the old-fashioned way (fabricating my own shunt),  does 
anyone know the full-scale millivolt input current for the OEM  ammeter?

Also, what wire gauges are used for the battery interconnects and for  the 
motor power and PTO connections?



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