Date:         Thu, 3 Aug 2000 21:18:19 -0400
Reply-To:     Bulley <gmbulley@bulley-hewlett.com>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Bulley <gmbulley@bulley-hewlett.com>
Subject:      Re: Alternator regulator voltage tolerances #

Drive with your headlights on. Worry about other things.

G. Matthew Bulley, Principal Consultant
Bulley-Hewlett Corporate Communications
Mount Olive, NC USA
877.658.1278 Tollfree
www.bulley-hewlett.com

My Agenda: Vanquish Suburban Sprawl.
My Methods: Revitalize mature urban towns. Champion mass transit and fast
Internet service. Demand replacement of archaic, "separationist" zoning
laws with neo-traditional mixed-use zoning.
The Result: Exceptional living/working alternatives; restrained sprawl; our
children inherit walkable, beautiful, interlinked towns. Find out more at
http://www.cnu.org


-----Original Message-----
From:   d t [SMTP:tinkerman@usa.net]
Sent:   Thursday, August 03, 2000 6:39 PM
To:     vanagon@GERRY.VANAGON.COM
Subject:        Alternator regulator voltage tolerances #

Hello Volks,

After struggling with a starter problem for a long time, I have finally
made
progress. The problem seemed to be weak battery related.
It turned out to be a sequence of causes: A alternator regulator set too
low
(13.8V instead of 14.4V), causing constant battery undercharge (because the
wiring dropped another 0.6V until it reached the battery) and low volatge,
coupled with excessive ignition switch and wiring resistance (the solenoid
draws over 10A!). Mutiple failures are always confusing...
This also caused complete discharge of the battery on long night drives in
hot
weather (i.e. headlights and A/C drawing lots of current) so I couldn't
start
if I stopped the motor.

After my battery bit the dust due to excessive discharges (also because of
that dreaded vanagon design flaw that keeps a parking light on if you left
the
turn signal lever not in the neutral position, even if the ignition is
turned
off - intensified due to the battery not being charged properly in the
first
place), I ran a complete analysis and convinced my car electrician that the
regulator might be set too low (13.8V). Although he argued 13.8V was OK he
agreed to replace the regulator. After removing it we saw it was marked
14.4V,
so indeed it seemed it was a bit low (a battery should be charged to 14.4V
and
then charging stopped (cycle mode), or left constantly charged to 13.8V
(float
mode), or a combination of both (smart algorithms). A battery should NOT be
constantly charged to 14.4V because it will overcharge and dry out).
He still argued it was OK, but agreed to replace it. Since he didn't have
an
original 14.4V Bosch regulator, he popped in a 15V aftermarket. Now things
were improving: the battery is charging to about 14.4V with no heavy loads,
but I'm worried  about overcharging.
The problem is that due to charging circuit resistances between the
alternator
and the battery, the voltage reaching the battery varies, depending on the
load on the battery (because they're connected at the battery, NOT at the
alternator and the alternator doesn't have remote sense as it should).

Now comes the question to the battery/alternator gurus:

1. Without heavy loads, the battery charges to 14.4V (not good for long
drives
due to overcharge danger).

2. With one heavy load (A/C), it charges to 14.0V (i.e. 0.4V voltage drop).

3. With two heavy loads (A/C and high headlights) it charges to 13.8V (good
for long drives, but can't recharge the battery in the normal short
distance
city driving with lots of starter activations).

What compromise would you recommend (I can install either a 14.4V or 15V
regulator with about 0.6V voltage drop on the wiring)?
The best would of course an adjustable regulator, preferably 2-step (13.8V
and
14.4V).
I've found in the archives mentions of adjustable regulators (motorola
alternators?), as well as modyfing the Bosch regulator.
Can anyone give some expert advice on this subject, as well as name a
source
for adjustable regulators (I have the 90A alternator) or other smart
solution
(e.g. adding remote sense)?

TIA
        Tinkerman


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