Re: [T3] DBB alternator related subject

["Dave Hall" <dave@hallvw.clara.co.uk>]

Blue wire on VR should be at chassis potential with ignition on and not charging
as the dynamo idiot light earths through the VR until the voltage rises enough
for the VR to supply current to the battery.  Relay coils don't take much
current.  Have I got this wrong - my system seems to work fine, but I concede
there might be a combination of bad battery or dynamo condition I've not
considered that could cause a problem.
So I guess the alternative is just to attach to D+ at the regulator.

Dave.
UK VW Type 3 & 4 Club
http://www.hallvw.clara.co.uk/
------
----- Original Message ----- 
From: "Russ Wolfe" <russw@classicvw.org>
To: "Type3" <type3@vwtype3.org>
Sent: Saturday, March 26, 2005 12:51 AM
Subject: Re: [T3] DBB alternator related subject


> On Fri, 2005-03-25 at 18:31, Dave Hall wrote:
> > > DUHHHHH, Just sitting here thinking about it. Connect the coil of the
> > > isolator relay to the D+ of the generator. There is no voltage there
> > > until the engine starts and the generator is above it's cut in speed.
> > > 12V Gen. cut-in = 2200-2300 armature RPM = 1000 RPM crankshaft. approx.
> > >
> > > -- 
> > > Russ Wolfe
> >
> > Russ, what's wrong with using the charging light output connection on the VR
to
> > operate the relay for the second battery?  It works fine on mine.  When the
main
> > battery begins to charge, there's 12V on that blue wire to turn off the
warning
> > light.   Not as sophisticated as Bosch's solution, but adequate for me.
> >
> Well, there is voltage on that terminal when the key is on. Yes, it is
> through the idiot light, but it depends on the inductance of the relay
> being used as to whether this voltage will pull the relay in.
> With using the D+ on the generator, you know it won't be pulled in until
> the engine starts.
>
> -- 
> Russ Wolfe
> '71 FB AT
> '66 FB MT
> '64 T34 (not running)
> '65 T1 (not running)
> '05 KIA Sorento SUV
> russw@classicvw.org
> http://www.classicvw.org
>
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