Unusual electrical issue

[johnny]

My 23' coach had a pair of solar panels (Siemens) and a controller. It kept the house batteries hot and the OEM stock isolator charged both properly
when the engine was running. I do very little dry camping, seldom more than wo nights without power except the genset. The chassis battery held up
without problems, just as it would in any vehicle parked for a couple of days. If I were worried about charging both with the solar charger, I'd feed
it to the center (Alternator) post on the isolator through a bucking diode, and adjust the system voltage output to produce the proper voltage at the
batteries. The bucking diode may already exist in the solar controller. If not, it needs to be about anr and a half times amperage of the solar
system.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased

 

[RF_Burns]

Hal,
If you move the alternator sense wire to the chassis side of the isolator, the alternator will output its rated voltage through the isolator to both
chassis and house batteries as OEM designed. (Lets say for illustration 14.2V after the isolator)

IF the solar panels are are generating enough power while driving on a sunny day, the solar controller will output your programmed voltage at 14.8V.
This increased voltage will be blocked by the isolator from reaching the alternator and chassis . Your house batteries will receive the higher 14.8V
and the chassis would continue to receive the 14.2V from the alternator. You will now get the benefit of the higher bulk charging voltage while
driving.

As you are driving down the road the solar panel will change. When the solar panel output drops such that your solar controller cannot output more
than the alternator voltage (14.2) the isolator will become forward biased and then pass charging current to the house batteries automatically.

When the engine is not running (camped), the house batteries will be charged by the solar (when available) or from shore power. The chassis battery is
isolated from the house batteries by the isolator as OEM designed. The chassis battery will not receive the higher 14.8V from the solar controller
which it is likely not rated for.

Just my farmboy shade tree mechanic way of seeing things.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that