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On my GM PD4106 I have moved the start batteries from the original battery box compartment(ahead on left rear wheel) to the space formerly occupied by the a/c compressor. The batteries are wired directly to the starter and there is a cutoff switch installed well.

In the old battery compartment I have placed two 6 volt golf cart batteries (wired in series for 12 volts) and these connect to the connectors formerly used for the start batteries.(also through a cutoff). When parked I disconnect the start batteries and connect the house batteries.

In trying to connect a string of LED lights I touched one of the wires in a flourescent fixture with a wire from the LED string. I was trying to see how much light the LEDS would provide. When I did this all the house lights went out. However, when I disconnect the house batteries and connect the start batteries everything seems normal and the engine starts normal. Also when I connect both the house and start batteries(with the engine shut off)all seems normal as well. I didn't want to try this with the engine running as this happened away from home and I didn't want to get stranded.

One further bit of complication. When the engine is running and the alternator kicks in  a "heater" light on the dash illuminates. Its not supposed to but when I rewired and replaced all the gauges/idiot lights a few years ago it just works this way and I have never changed it. However, now when I try and run the house lights/etc. off the house batteries this "heater" light on the dash comes on even with the engine not running.

Anyone have an ideas on what to look for.

Thanks
Fred McNeill.

So it would seem from what you are saying that your house system is not really isolated from your start system.  Is that right?

Is your coach 24 volts?

I believe the 4106 is 12 volts. I like to use a test light and work my way from the main switch to the final fuse checking for good power.  Test lights can be better than volt meters for this kind of stuff because the volt meter load is so small a bad connection can still show a 12 volt reading.

-Tom Phillips

 "So it would seem from what you are saying that your house system is not really isolated from your start system.  Is that right?"

Probably not. I can isolate the start batteries separately and I can isolate the house batteries separately but each set of batteries (or both)feeds into the house system  when connected.

The bus is 12 volts.

Thanks

Fred

look for a good electrician.......put the starters back where they belong as you will have too long of a wire run and that may cause problems. two 6 volt batteries are really not enough for a house system use the space in front of the a/c box for at least 6 of those batteries.

Actually, by moving the start batteries (which was done 3 years ago) I cut the length of the cables in half. That has been working fine for 3 years. And having just two 6 volt house batteries has worked OK for a year as well. I agree that more would be nice and will do that eventually. That isn't my problem. My problem is that I did SOMETHING to screw up that setup and am trying (hopefully with the help of the tremendous resources on this board) to figure out how to correct it.

Regards

Fred Mc.

Sounds as if you are back feeding the coach circuit from the new house battery set up. Check the circuits that were fed from that location. Is it possible that the alternator excitation was directly fed from original start battery Junction block or possibly there could still be a circuit at the starter that could be back feeding.