The 14.2-14.3 VDC is a good voltage for bulk charge of the battery, but
can cause it to boil (gas) if held after the charge is complete. This
may shorten the life of the battery, but it should still charge. A much
lower charging voltage will cause the battery to sulfate, decreasing the
capacity over time. It's sort of a compromise with the older 'not
smart' regulators. That's why most 'modern' alternators are under the
control of the engine computer, which can implement a '3-stage' charging
algorithm that maximizes the battery life. My recollection of the
regulator on the VW is that it has a 'current' coil that will shut
charging down for a while when the charging current gets low. A failure
of this to reset could be your problem. I have taken regulators apart
and filed the contacts inside to restore them to usefulness
(temporarily, they will burn again....).
The 'definitive' check to distinguish between failure of the generator
and the regulator is to ground the "DF" terminal of the generator, at
the generator or at the regulator. The generator should go to something
like 15V, more than the regulated voltage when it is under control. To
make this work, you would need to do it after the light comes on and
your battery voltage is lowering, you seem to have sufficient voltage
'around town'. Next time it fails, ground that DF terminal (the little
one on the generator - don't try to ground the hot lead!) with a jumper
and read the output voltage of the generator. (don't leave the jumper
on very long, it can damage the generator and/or battery). If it goes up
to >14.5 V, it is the regulator causing the trouble, if it doesn't (no
change in voltage, basically) then the generator is the problem. Good luck!
glenh :<)>
On 12/19/2015 2:37 PM, Mike Morehouse wrote:
Glen and others who have replied. I have connected my DVM to the
battery so I can see what voltage the gen is delivering to the battery
why I drive around town. Yesterday was seeing about 14.2 - 14.3
In order to check he regulator, whch wire do I disconnect at the reg
and ground?
Mike
On Sat, Dec 19, 2015 at 10:07 AM, Glen Hadley <[email protected]
<mailto:[email protected]>> wrote:
Actually, over 14V at the generator is probably too high. A max
of 13.8V is generally considered enough. Sounds like it is
overcharging the battery, much over 12.5V resting is a bit high.
My guess is the regulator - it could be shutting down completely
on a long trip after the voltage hits some threshold instead of
keeping the voltage up. If it's holding 14+V, the generator is OK
- that's what you should see if you ground the control terminal of
the generator, which is a sign that the regulator is the problem.
glenh :<)>
On 12/13/2015 1:10 PM, stokester wrote:
Yup.
A 100% charged battery should read 12.6 volts, 12.4 = 75%, 12.2=
50% and so on.
Over 14 volts from the generator should be enough to keep it
charged and provide enough juice to run the vehicle.
So your battery shows that it is fully charged and the generator
is providing a charging voltage but there may be other factors.
The battery may read fully charged but until you do a load test
its capacity is not assured. The generator has brushes with
springs and a commutator which may be worn causing them not to
make full contact.
As John mentioned, heat may be a factor. As the armature and
other components heat up there may be other things going on.
Nick
On Saturday, December 12, 2015 at 3:19:11 PM UTC-5, mike
morehouse wrote:
After trickle charging the battery over the last few days
till I got a green light indicating it was charged, the
battery output with the engine off is 12.65. I started the
bug and let it idle. No gen light. Revved up the engine and
checked the voltage at the battery and it was reading about
14.3 vdc.
Wouldn't this indicate that the generator is ok?
What to check next?
Thanks Mike
Mike Morehouse
On Dec 12, 2015 1:30 PM, "stokester" <[email protected]> wrote:
The first thing I would do is use a meter on it to see
the actual output voltage of the generator.
Nick
On Friday, December 11, 2015 at 9:54:34 AM UTC-5, mike
morehouse wrote:
Good morning.
I need a little advice with a generator light issue
on my stock 72 Bug with generator. I drive my Bug
mostly short trips in town - errands, church, work,
etc...both day and night driving. Car is stock with
OEM generator. No added accessories. Battery was
replaced in 2012 and starts car fine.
I never have any generator light issues on normal
trips in town. Last night I took it up the
interstate on about a 22 mile trip at about 65 mph
and at the 20 mile mark the gen light came on. Car
contined to run fine. Got to my destination and
picked up a play script and got back in the car to
make the 22 mile trip back home. Gen light stayed on
the whole time. FYI, I did notice left and right turn
signals were flashing very rapidly when I put them on
on way home.
As I got close to home it did appear that headlights
were getting dimmer. Made it home OK. Pulled in
garage and left engine running to look at headlights.
They did look dim. Shut engine off. Checked fan belt.
It was intact and seemed to have plenty of tension. I
connected my Harbor Freight trickle charger to
battery and left it on over night. It is still
charging this am. If I do start car this am,
headlights seem fine and there is no gen light on.
IIRC, the last time I made his same length trip, the
same thing happened.
Why would I have gen light issues on a 20 mile trip
at 65 mph when I never see that around town?
Would a 30 or 35 minute trip cause a gen problem that
a 10 minute trip around town might not?
I guess what I am saying is no gen light occurrences
on numerous local trips but 2 consecutive light
issues on 30 min trip up interstate.
I'd welcome your thoughts as this makes me wary of
taking an road trips in the Bug.
If I didn't give enough info on symptoms please let
me know as I do need some help.
Thanks Mike Morehouse in Alabama
--
Visit the VintagVW archives at
http://www.mail-archive.com/[email protected]
---
You received this message because you are subscribed to
the Google Groups "VintagVW - Air Cooled Volkswagen
Discussion List" group.
To unsubscribe from this group and stop receiving emails
from it, send an email to [email protected].
To post to this group, send email to
[email protected] <mailto:[email protected]>.
Visit this group at https://groups.google.com/group/vintagvw.
For more options, visit https://groups.google.com/d/optout.
--
Visit the VintagVW archives at
http://www.mail-archive.com/[email protected]
---
You received this message because you are subscribed to the
Google Groups "VintagVW - Air Cooled Volkswagen Discussion List"
group.
To unsubscribe from this group and stop receiving emails from it,
send an email to [email protected]
<mailto:[email protected]>.
To post to this group, send email to [email protected]
<mailto:[email protected]>.
Visit this group at https://groups.google.com/group/vintagvw.
For more options, visit https://groups.google.com/d/optout.
--
Visit the VintagVW archives at
http://www.mail-archive.com/[email protected]
---
You received this message because you are subscribed to the Google
Groups "VintagVW - Air Cooled Volkswagen Discussion List" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to [email protected]
<mailto:[email protected]>.
To post to this group, send email to [email protected]
<mailto:[email protected]>.
Visit this group at https://groups.google.com/group/vintagvw.
For more options, visit https://groups.google.com/d/optout.
--
Visit the VintagVW archives at
http://www.mail-archive.com/[email protected]
---
You received this message because you are subscribed to the Google
Groups "VintagVW - Air Cooled Volkswagen Discussion List" group.
To unsubscribe from this group and stop receiving emails from it, send
an email to [email protected]
<mailto:[email protected]>.
To post to this group, send email to [email protected]
<mailto:[email protected]>.
Visit this group at https://groups.google.com/group/vintagvw.
For more options, visit https://groups.google.com/d/optout.
--
Visit the VintagVW archives at
http://www.mail-archive.com/[email protected]
---
You received this message because you are subscribed to the Google Groups "VintagVW - Air Cooled Volkswagen Discussion List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at https://groups.google.com/group/vintagvw.
For more options, visit https://groups.google.com/d/optout.
