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Old 11-26-2007, 10:38 AM   #206 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 54.01 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)
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12-28-2006, 09:24 Pm

Quoting myself from earlier...

Quote:
Quote:
Originally Posted by MetroMPG
I believe controllers "charge" before they go into action, so that may be the source of the spark.
I did some digging in the EVDL archive and I was correct in my belief about the initial spark:

Quote:
Quote:
When you first get in the car, the controller caps are discharged and appear as essentially a dead short. If you simply close the main contactor and apply full pack voltage to the controller, the inrush current can be *huge* (as in 100s of amps).
(from http://autos.groups.yahoo.com/group/.../message/78835)
That would explain where our spark came from and why we only it once: we charged the caps in the controller when touching the pack cable to the controller. It also serves as an explanation of the function of a precharge resistor (to protect the caps & the contactor - or cable tip & controller terminal, in our case - from excessive current inrush).

So tomorrow, I should look at the pot and see if it's the problem.
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