RE: (ET) Getting around that shunt

["Chris Tromley" <chris_t microtrac com>]

Chris Zach wrote:

<a clever idea to bypass his shunt when not needed>

I like it, but thought I'd offer this as well.  (Keep in mind I'm an
electrical idiot.)

It may be a problem to find space for the new contactor.  If so, is it
possible to do some reverse engineering on the card that holds the
transistors?  You might find that you can replace them with modern units
that achieve the same function with a much smaller voltage drop from the
shunt.  Then replace the shunt with one that gives a millivolt drop
instead of tenths of volts.  Same functionality, same number of parts in
the same places, higher efficiency.

Or if you're only concerned with the existing shunt getting stinking
hot, how about replacing it with a "calibrated" length of 0 (or other)
cable and run the sense leads to the cable ends?  The heat dissipation
would be distributed over the length of the cable, so there would be no
stinking hot shunt.  No improvement in efficiency either, because you
still need the same voltage drop for the card to work right.

Chris Tromley
Philadelphia  PA
USA

100% Gas-Free Yard Equipment:
* Avco New Idea EGT 150 electric tractor (equivalent to GE Elec Trak
E15M)
  Need a snow blade!
* B&D corded electric mower and string trimmer
  - to be powered by tractor-mounted inverter some day
* Patriot 1.5 hp electric chipper/shredder/vac
  - to be turned into a tow-behind vacuum cart some day
* Remington corded electric tiller
* Craftsman corded electric snow thrower
  - to be sold when I get a blade for the tractor