RE: (ET) RE: Alltrax DCX300 availability - Field current

["David Roden (Akron OH USA)" <roden ald net>]

On 26 Jan 2005 at 15:33, john briese wrote:

> If I were doing it again, I would: 1) Install an inline fuse
> with the controler, which could be removed after successful install.

This is one of the changes I made to Steve's instructions - not without 
spending a lot of time considering where the fuse should be located, and 
what its effect might be if it opened.  I didn't remove the fuse after a 
successful installation though.  I can't see any reason not to keep it 
there 
forever.  I don't know how well it really protects the controller - too 
often 
silicon blows to protect the fuse <g> - but it's certainly better and 
safer than 
no fuse at all.

I put the fuse in the line which provides 36v for controller logic power, 
and the 
control voltage for the throttle and reverse switches.  My old fuse panel 
had 
gotten pretty flaky anyway, so I just replaced it with one that had four 
positions instead of three.  I suppose one could fit an inline fuseholder 
under 
the instrument panel if that's easier.

I used a 7 amp instrumentation fuse.  I'll probably replace it with 
something 
like 2 or 3 amps later, but 7 amps was what I had on hand.

I also connected the thermal breaker on the motor in series with the seat 
switch and key switch, instead of in series with the armature, as Steve 
suggested in the manual.

Finally, I retained the main disconnect (I think Steve junked his only 
because 
it was already broken).  The typical failure mode for a transistor 
controller is 
full speed ahead.  So even though there's a main contactor, I don't think 
it's a 
good idea to run without a redundant manual safety shutdown.

There are a few more things I still want to do as part of this upgrade 
when the 
weather warms up.  One is a charging lockout.  This may be a bit of a 
pain, 
since I use three 12-volt chargers rather than the GE charger.  

Another is a Sonalert or similar gadget that sounds when I get off the 
tractor 
but leave the key on, a bad habit that I have.  I think I saw one of the 
electronic seatbelt dingers (as used in cars) at one of the electronic 
surplus 
places once; that would be kind of cool.

The last and most important is a high pedal disable.  This is a function 
that 
refuses to let the vehicle move if the accelerator pedal is already 
depressed 
when the key is turned on or the brake is released.  It's standard on golf 
car 
and road EV controllers, and GE implemented it on the ET's original 
controls.

I was surprised and disappointed to find that the high pedal disable on 
the 
Alltrax ET controller is ... disabled!  It's apparently included on their 
golf car 
controllers, and there's an option to enable it in the Alltrax software, 
but 
checking that option has no effect.  The reason for omitting this feature 
from 
the ET version of the controller (at least the early one I have) is a 
complete 
mystery to me.  

As a result, I can open the throttle pot all the way and turn on the key; 
the 
tractor will take off running.  Or I can hit the brake while plowing; the 
tractor 
stops, but then when I release the brake the tractor starts right up 
again.  
Some people will probably consider this a convenience, but I see it as a 
hazard.  So I plan to implement something externally, probably using the 
potbox microswitch and an SCR or a small relay.  (Suggestions welcome.)