Curtis Woes

[Doug Pratt <dpratt@pacific.net>]

Hi Folks,

  I've been off the list for a couple years, couldn't handle the daily
volume, but after blowing three top-of-the-line Curtis controllers in a
month, I need some of this group's experience.  Any advice will be
appreciated.

  I've got a 1980 ElectraVan 750, it's a Ford Courier conversion. I've
upgraded it 144v (T-105 wet cells), a Curtis 1231C controller, K&W
onboard charger, Todd DC to DC charger...it's a fairly typical
conversion.

  It got a new battery pack in early November.  Just before Thanksgiving
the three-year old Curtis expired quietly while creeping across the
parking lot.  It had just been unplugged from the charger, so battery
voltage, due to residual charge, was still real high.  The Curtis has
always been balky under these conditions.  There was no fire or drama,
it just did it's normal squeal, but with only tiny output...it was
drawing 10 to 15 amps according to my E-Meter.

  Got towed.  Ran thru the Curtis troubleshooting flow chart at home.
All the externals check out okay.  Got voltage, contactors work, potbox
runs thru normal resistance range.  What I don't have is controller
output.  Measuring from B+ to M- terminals, I should have full battery
voltage at full throttle.  I read 3 to 4 volts, and the motor spins
slowly.  Flow chart sez the controller is defective at this point.

  Did the $300 rebuild turn around with Curtis.  Got a different
controller back, actually a brand new one.  It ran for 1-1/2 trips to
work, less than an hour of run time, and expired the same way.  Squeals
loudly, passes 3-4 volts and 10-15 amps.  The Curtis folks protested
(understandably), I had a long talk with one of their engineers, and
then they scrambled together another controller, and got it off to me
just before they closed for the holiday week(s).

  This second rebuilt unit expired before even spinning the motor up in
neutral.  Same symptoms.  Squeals loudly, passes 3-4 volts and 10-15
amps, the motor spins slowly.  It's a GE motor, I pulled out the front
battery box to carefully check brushes and motor connections.  They're
all good and tight.

  I'm ready for any tips, suggestions, or advice.

Best regards,
Doug Pratt