Ground fault after running engine on RV

Started by Jphoenix13, July 17, 2019, 04:26:18 PM

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Jphoenix13

I have a Classic 150 managing about 1.3 kW solar on top of my Wanderlodge. Also have a 110 vac battery charger and 200 amp alternator in the system. Classic works perfectly with solar and also when plugged into 110 shore power with battery charger working in the evening and in the morning the Classic wakes up from its rest and charges all day just fine for weeks on end.

I say weeks on end because the bus lives in a storage lot for most of the winter and even up here at 48 north the solar keeps the seven batteries fully charged throughout the winter. 👍

Problem is after I start the engine, alternator comes on line, charging nicely and no problems until after I shut down and find the Classic resting and it shows ground fault. So something is happening when the alternator comes on line that trips the ground fault. After engine shutdown, I simply press the button to start the Classic charging again and it recovers just fine.

Do I have a ground missing somewhere between the alternator and the Classic? They are all wired together at the battery bus, positive and negative, no isolator, 110 vac charger, alternator and Classic (coming out of the combiner box).

Thoughts and suggestions appreciated.

boB

Interesting that it recovers.

I assume that the battery and PV negative are connected to chassis of the RV through the Classic.

The Classic's GND or chassis is connected to the RV ground by way of mounting screws.

And then the battery and PV negative, being connected to the Classic negative terminals gets connected to ground via the PTC (~500 mA resettable fuse) inside the classic.   Some current goes through that PTC and opens it up and the sees a difference and it trips and beeps and wants to be reset but should complain again after you press a button to reset it.   What is weird is that it lets you keep operating.  So MAYBE there is just a pulse of current differential when the engine starts up ? 

One of the positive lines, either PV or battery plus would be possibly connecting to the RV ground briefly.

Does this happen during the day when sun is shining on the panels ?  If it does it during the day but not during the night, then maybe it is coming from the PV.
If it complains day or night when you start the engine, then it is probably battery negative.  You could measure voltage with a meter between negative terminal and chassis when this happens and see what you find.

We'll start there but I may be totally off the mark.

K7IQ 🌛  He/She/Me