It's a little reminiscent of one failure mode in the old PMC (pre-Curtis) 
controllers.  The circuit that derived the logic voltage from the traction 
battery had an undersized power resistor.  If it opened, the logic voltage 
would go low, making the controller think the battery was flat.  The 
controller would be stuck permanently in "turtle mode" where it would limit 
current to something really low, like 20a or 50a.  You could move the car 
round your driveway at crawling speed if you were lucky, but that's about 
it.

I don't remember that that condition could be reset by power-cycling the 
controller, however.

Here's a wild, irresponsible guess from a non-engineer : something that 
should be heatsinked isn't; or, it's just getting hotter than it should be.  
When it heats up, the controller realizes that, and - to protect itself - 
either shuts down or knocks the current limit way down.

I'll sign off now and let the folks who actually know something have at it.

David Roden
EVDL Administrator
http://www.evdl.org/


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