The usual instrument for measuring insulation leakage is called a
"megger" or "hipot tester". This can give you a quantified value of
the leakage in ohms-per-volts. Most any motor shop will have one, and
can test for you.
Finding your fault is likely going to me more involved even if you
buy or borrow the megger. I sniffed for leakage in my hydroelectric
generator wiring by building a GFCI tester out of the cord from an
old pressure washer and a light bulb, and went looking for the fault.
It's a go/no go proposition, disconnecting parts of the circuit and
testing, repeating as many times as necessary until you stop getting trips.
In your case, since you aren't getting consistent tripping, you
either need to find a GCFI that trips consistently and use that to
test, or increase the amount of leakage in the test circuit to just
below the threshold of tripping, then connect the car, which should
trip the GCFI until the fault is corrected. Adding some very high
value resistors between the "hot" leg of the GFCI output and ground
will increase it's sensitivity. This, by itself, might be a trial and
error project, and will require some number of resistors on hand to
experiment with. You will be careful when fiddling with this, right?
Of course, you know where to look for common fault paths in the car?
Motor brush carbon dust, dried and cracked insulation on high voltage
conductors, intrusion of road splash and dust near energized
conductors, etc? Any place that pack voltage and 12 volts from the
cars electrical system come together, even come close at all, are
highly suspect, metering, BMS, relays and contactors, etc. If you
start getting close to the problem(s), then a visit to the motor
shop's megger might be more informative.
The ultimate solution might be to have a big, heavy isolation
transformer that you lug around everywhere. That was one of the good
features of the old Lester chargers, full isolation, and they made
your car ride stylishly low, no need for coil-overs...
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
ARCHIVE: http://www.evdl.org/archive/index.html
INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
