(ET) New 'almost failure' mode... Motor power, etc.

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

OK, a new 'almost' failure mode.  

I have been working on ET's for 7 or 8 years now.  I thought I had 'seen it
all' (well, I knew better I guess...) but here's a new one:

I go out to mow.  I go to lower the front lift and it doesn't go down.  I
check the fuse socket (they get rusty... very common) but that isn't it.
Hmm.  I start looking around.  I go to trace the wire to the lift 
and... huh?  The wire isn't on the back battery!  When set up right, the
lift goes to a terminal on the back 
set under the seat, front battery on the right.  The terminal has MELTED.
The wire fell off.  The tractor is STILL RUNNING.  The cable stayed in the
pile of lead that was the terminal.  I had been tilling, and I 
suspect the connection was very loose.  I got hot, but kept working.  It
melted but kept working.  I touch 
the lift wire to the terminal and it still goes up and down.  The battery
still tests good.  I'm going to 
try and make a more rugged connection to what's left of the terminal.




BTW, as far as comparing an ET with a gas tractor, several things need to 
be
noted:

42V (or perhaps 40V) at 100A is CONTINUOUS.  You might go 200A for a brief
period.  The POWER at 100A is 
still only 5.5 HP, but that is the speed at which you can create torque.
The torque for a gas engine is 
fairly flat, but for an electric motor, the torque INCREASES at low RPM.  
It
is more like a steam engine.  
Lots of old steam locomotives were 12 to 20 HP and pulled many tons, but
they were only doing 12 to 20 HP. 
When GE bragged that the motor could put out 20 HP, it was brag, but the
motor puts out about the same 
torque (briefly) as a 20 HP gas engine.  It isn't just the silly way that
marketers try and sell power 
tools and over rate the HP based on impossible criteria. 

That 5.5 HP will out pull a gas tractor of much higher HP, BUT NOT AT 
SPEED!
The gas tractor can do more total work in a given time.  In addition, that
gas tractor only puts a fraction (75% or so) of it's power 
to the wheels.  It also has to share the power with the mower deck or
whatever.  The ET does the deck as 
a separate module of 3 roughly 1 HP electric motors, so you gain there too.




Larry Elie