[Vwdiesel] Alternator Issues

Wed Jun 27 11:13:57 EDT 2007

What you get for voltage will depend upon your battery, any load and the 
alternator output.  The alternator output will be predominantly be influenced
by the regulator.

Normal levels would be about 13.6 volts.  Could be up to 14.4, but my
guess is that you'd be going through headlights faster with that kind 
of a voltage.  If it's 12.2 and the battery is "fully charged" then
you still have some kind of a problem.

The current output will vary, and a simple way of thinking about it is that
an alternator will try to provide whatever current it can, to maintain
the voltage the regulator is set for.  Things aren't perfect,
and the voltage will be higher at low loads, or high RPMs.  An alternator
will produce more power at higher RPMS (although less dependant upon
RPMs than a generator).

One thing I've done in the past is to change pulley sizes on alternators
to get higher RPMs, and higher current output of the alternator at low
engine RPMs.  (For emergency hilltop ham repeater operation...an old
79 diesel Rabbit will run all weekend on less than a tank of fuel.)

What kind of voltage are you actually seeing, and under what load and
engine conditions, with your alternator?

Val

> 
> Update, I replaced the alt with one i had. I have a bench testing system th=
> ough am wondering if the current produced varies. I see some say 14.4. when=
>  i check current accross the battery term's, I get high 12's to mid 13's th=
> ough the battery is fully charged as it was on the plug in charger.=20
> > From: val at mongo.mongobird.com> Subject: Re: [Vwdiesel] Alternator Issues>=
>  To: rgreeley2 at hotmail.com> Date: Mon, 18 Jun 2007 16:57:16 -0400> > It's g=
> oing to be pretty difficult to walk you through the diagnosis.> > You've es=
> tablished that you don't have any charge.> > Did you pull the voltage regul=
> ator and brush assembly, and see if the > brushes are past their wear limit=
> s?> > >=20
> _________________________________________________________________
> Make every IM count. Download Windows Live Messenger and join the i=92m Ini=
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> Update, I replaced the alt with one i had. I have a bench testing system th=
> ough am wondering if the current produced varies. I see some say 14.4. when=
>  i check current accross the battery term's, I get high 12's to mid 13's th=
> ough the battery is fully charged as it was on the plug in charger. <BR>
> <BR><BR>&gt; From: val at mongo.mongobird.com<BR>&gt; Subject: Re: [Vwdiesel] =
> Alternator Issues<BR>&gt; To: rgreeley2 at hotmail.com<BR>&gt; Date: Mon, 18 J=
> un 2007 16:57:16 -0400<BR>&gt; <BR>&gt; It's going to be pretty difficult t=
> o walk you through the diagnosis.<BR>&gt; <BR>&gt; You've established that =
> you don't have any charge.<BR>&gt; <BR>&gt; Did you pull the voltage regula=
> tor and brush assembly, and see if the <BR>&gt; brushes are past their wear=
>  limits?<BR>&gt; <BR>&gt; <BR>&gt; <BR><BR><br /><hr />Make every IM count.=
>  Download Windows Live Messenger and join the i=92m Initiative now. It=92s =
> free.=A0 <a href=3D'http://im.live.com/messenger/im/home/?source=3DTAGWL_Ju=
> ne07' target=3D'_new'>Make it count!</a></body>
> </html>=
> 
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