> I almost hate to ask this question.  I am adding a relay and aux battery
> to
> my passenger van.  The relay came from a weekender and I currently have my
> 2
> batteries connected directly together and not using the relay.
>
> So my question is can the relay tell the difference between battery
> voltage
> and charging voltage (I wouldn't think so).  But if not what triggered the
> relay to close only after the van was running.
>
> Clarification is greatly appreciated, but please no wiring diagrams or big
> words.  I liked the way the relay worked in my dual battery camper and I
> would like to set it up to work the same way in my new van.

In a nutshell? The aux relay is powered off the blue wire coming from the
back of the alternator. The blue wire shows voltage only when the alternator
is charging.

It  gets more complicated* than that, but it all basically starts with the
blue alternator wire.

*My own setup: blue wire triggers "alternator working" relay, which supplies
12v to coil of solenoid-type aux battery relay. The solenoid coil grounds
through the NC contacts of a "starter in use" relay which is activated by
power to the starter solenoid, thus disconnecting the aux battery while the
starter is cranking.
-- 
John Bange
'90 Vanagon - "Geldsauger"