Thanks David.

I wondered what would happen.

FWIW, the 12V DC "shore" source is 110 AC to 12V DC using an AC
adpator. (wall plug)

I didn't note that in the diagram. My bad.

Still, I'm doing it wrong.

Thanks for help.

Neil.

On 8/6/07, David Kao <dtkao0205@yahoo.com> wrote:
> Neil:
>
> It looks to me the internal fan will see +12V from either home or shore
> battery depending on the position of the DPDT switch.
>
> If the rear fan switch is closed (conected) you will not get 24 volt.
> It will still get +12V from either the home or the shore battery.
> But if it gets +12V form the shore battery (through the DPDT switch)
> and the thermal switch is closed at the same time it will put both
> batteries in paralle, meaning it shorts the +12V leads of the two
> batteries. This is a problem. If one battery has a higher voltage than
> the other there will be current flowing from one battery to another,
> which is like charging the of a lower voltage. It may not cause
> any damage to anything if the voltage difference between the two
> batteries is very minimum. But if the difference is not very small
> It would be like shorting a voltage of the difference, which could
> easily burn the wires or the switches at the moment they are connected.
>
> Batteries should never be connected in parallel.
>
> David
>
>
>
> --- neil N <musomuso@GMAIL.COM> wrote:
>
> > Hi all.
> >
> > The diagram:
> >
> > http://web.mac.com/tubaneil/iWeb/Site%205/DometicWiring.html
> >
> > Fans work properly from both power sources. Internal is switched at
> > DPDT, and rear is switched dependent on power from DPDT.
> >
> > IF thermal switch went "on" AND power still "on" from either source,
> > will rear + internal fan see app. 24 volts if "rear fan switch closed?
> > Or are they in series? (remains app 12V)
> >
> > Many thanks, if anyone can answer!
> >
> > Neil.
> >
> > --
> > Please send me your Vanagon/Westfalia links!
> > http://vanagonlinks.googlepages.com/home
> >
> > Neil Nicholson. 1981 Air Cooled Westfalia.
> > http://web.mac.com/tubaneil
> >
>
>
>
>       ____________________________________________________________________________________
> Park yourself in front of a world of choices in alternative vehicles. Visit the Yahoo! Auto Green Center.
> http://autos.yahoo.com/green_center/
>

--
Please send me your Vanagon/Westfalia links!
http://vanagonlinks.googlepages.com/home

Neil Nicholson. 1981 Air Cooled Westfalia.
http://web.mac.com/tubaneil