Date: Sun, 14 Oct 2012 22:30:10 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Overheated wire junction on 1.9
In-Reply-To: <507AD477.1010905@gmail.com>
Content-Type: text/plain; charset="US-ASCII"
The alternator wire overheating is not unique to you and your charging
system, especially with that current limiting charge controller did not
cause the problem by itself. The wire is normally highly loaded and heating
up is normal operation. The connections are crimped, and the exposed copper
is open to the elements. Failure of this wire is common on both ends. Part
of the design may be to limit the current the alternator will supply however
it is the first major voltage drop and after 28 years of service and
exposure it owes you nothing. The alternator is rated for 90 amps. If you
were installing a 100 amp branch circuit in you r house you would be
starting with#2. Not 2 #12s. My suggestion! #6 going from alternator to Batt
positive cable on starter, A #8 from main battery to fuse-ignition switch. A
#8 from alternator to charge control relay and then to your house battery
bank. Then a #4 ground from alternator case/mount/bracket whatever to the
chassis. Use real heavy duty crimp connections and shrink tube to seal the
copper. Want to go all out get the tinned copper wire as is used for marine
applications. You will be surprised how much better everything will work.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Rocket J Squirrel
Sent: Sunday, October 14, 2012 11:04 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Overheated wire junction on 1.9
I want to describe an issue I found while working on my van. Most will
probably not have this problem unless they are running an '83 or '84 digijet
(1.9) camper van and draw a lot more out of the alternator than a stock van
does. But if this fits your situation, it bears inspecting for this
potential problem.
I'm in the process of totally revising the charging system because I am
increasing the size of my house battery. The previous house battery (which I
killed by letting it discharge) was a 130 amp-hour deep cycle.
To charge it I used a DC > DC battery charger* set to the high-current
15 amp mode (later versions are limited to 7 amps, but 15 amps better-suits
larger batteries like mine).
The charger pulls about 18 amps from the van's charging system. The wiring
to the charger was less than ideal:
alternator > van wiring > engine battery > relay > charger > house battery
(located under bench seat).
The weakness is the van wiring. With a heavy load placed on the engine
battery, there are a couple problems:
The first is that the wiring isn't hefty enough to carry that much current
without losing some voltage, so the engine battery never gets a full charge.
I found the second problem when poking around in the connector box located
in the engine compartment on the firewall forward of the engine on the
driver's side.
Bentley 97.56 shows a pair of 12-gauge wires coming off the alternator's
B+ terminal and going to the plus connection** in that box. Then a
single 8 gauge wire carries the current to the starter, where a 2 gauge wire
brings the charging current to the engine battery.
When I opened the box I saw that the last inch or so of the wire pair had
darkened insulation, and the connector used to connect them to the plus
connection was nearly black.
Clearly the heavy load I'd been placing on the wiring had overheated that
connection, increasing its resistance and further reducing the charge
voltage on the engine battery.
Though the heavy current draw through that route will no longer exist,
because I am adding a new 0-gauge wire from the alternator directly to a new
relocated charging circuit right at the new house battery, I still bypassed
that weak link by installing a new wire directly from the alternator to the
starter using a pre-made cable from Van-Cafe (search for VC.ALTCABLE***),
leaving the old wiring in place for whatever the heck else gets powered off
Connection 21.
I hope this will encourage owners of the 1.9l van to at least take a look
inside the connector box to make sure their charge wire isn't showing signs
of heating. The box snaps open, it's easy.
=============
* Powerstream PST-BC1212-15 <http://www.powerstream.com/DCC.htm>
** Connection 21, seen on Track 22 on 97.56 and mislabeled as a "ground
connection" on Bentley 97.54.
*** Or make your own. I didn't measure the length of the Van-Cafe part
before installing it, but you'll want a large-gauge cable with a pair of
5/16'' ring lugs on the ends.
--
Jack "Rocket j Squirrel" Elliott
1984 Westfalia, auto trans,
Bend, Ore.