TEVan charging problem

[Rod Hower]

I decided to pop the cover off the TEVan control
and bypass the on board GFI.  It didn't have one
on the control card!
I now remember that the on board GFI had a tendancy to
trip so they moved it to a commericially available GFI breaker.
So, why was the charger tripping?
It turns out the PTC that measures battery temperature was
open circuit.  The charger thought the battery was too hot.
I actually think it was an intermittent open circuit since
the van charged sometimes.
I installed a 10k resitor at the PTC input terminals and it
charges fine (10k is about 25 degrees C).