Date: Sun, 12 Dec 2010 23:24:56 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Battery or Charging System Help Please
In-Reply-To: <4D059188.10603@cisaz.com>
Content-Type: text/plain; charset="us-ascii"
This is a common ailment as these vans get older. It can also indicate a bad
ground from the alternator. Measure for voltage from the alternator case to
the chassis. If you get more than 1/4 volt you need some more grounding.
Another wire from the alternator to the battery cable and then another from
the battery to the fuse box will do wonders for all accessories. You can
also run a wire form the alternator to the fuse box directly. #8 is a good
size. #6 is better but makes connections more difficult.
As a side note the heater blowers should not be run a high speed for long
periods of time. Not good for the wiring or the motors themselves. From a
heat performance point there is also no benefit. The front heater is all
outside air so the more air the less it gets heated. Note the #2 near the
little pictogram for the defrost function. Fan speed 2 is probably the best
compromise. Once the van if fairly warm and you are traveling on highway no
need for the blower at all.
As for the rear the air is re-circulated but weather you heat 10 cubic feet
per minute, (cfm) 20 degrees or 20 cfm 10 degrees really doesn't make much
difference. If you find it difficult to heat the van you probably need new
heater cores. The front tends to get loaded with road dirt on the outside
and due to leaks gunk on the inside. You should be able to keep the inside
about 60-70 degrees above outside.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Michael A. Radtke
Sent: Sunday, December 12, 2010 10:23 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Battery or Charging System Help Please
Hello,
I have owned my '84 GL since new. I live in Phoenix Arizona and all my
battery failures have been typical of the climate: shorted cells.
However, I am now faced with a cool weather problem that I have no
Vanagon experience with.
The symptom is that the engine cranks slowly even after a long drive.
If I charge the battery, the engine cranks just fine for a few days.
So, I looked at the charging system and was reminded again that the
Vanagon uses an alternator that supplies a constant voltage at its
terminals instead of supplying a constant voltage at the battery. With
the engine at 1000 rpm, I measure 13.8 volts at the alternator with the
lights and heater blowers turned on, but only 12.6 at the battery. That
is not enough to maintain the battery.
It is most likely that there is a high resistance path in the wiring
between the alternator and the battery. Bentley shows two parallel
wires from the alternator that connect to a bus wire that runs from the
heavy starter cable to the front of the Vanagon. I don't know why VW
didn't run those parallel wires directly to the starter cable. I
suspect the junction of the parallel alternator wires and the bus wire
is bad, but I can't locate the connection. Can anyone tell me exactly
where it is?
Of course, any other advice on how to trouble shoot the problem would be
appreciated as well. Searching the archives I saw that some folks have
gone to an external regulator with battery voltage sensing to fix the
low charging voltage problem. However, my Vanagon has been running as
designed for more than 25 years, so I should probably just fix the
problem instead of trying to improve the design.
Thanks,
Mike
