Thanks again Paul:
>BTW, whilst you should have about 14.5v (except on heavy loads) at the
>this may well be 14v at the brown on the fusebox, lower again on the >white
>and still lower on the green, quite possibly down to the 13.5v that you
>mentioned at one point. All this is relatively normal for cars of this
age,
>and would probably need all new electrical wiring, connectors and
>components
>to improve"
Yep that is true, and anything above nominal battery voltage of 12.8VDC is
_actually_ charging the batts. But I also know that the past weeks charging
problem has made the battery quite low, and 13.5V at the battery is ok until
batts are more charged.
Also I found my problem this am!!
Thanks to your comment about solenoid, and putting a meter right at the
alt!! After consulting the wiring diagram, I the large brown from alt to
solenoid broken and "barely" touching. So I stripped and soldered the wire
as a temporary patch.This accounted for the charging when decelerating and
discharging when accelerating. Actually all 5 wires down there are pretty
beat up and bare, so I am going to schedule an hour or so this weekend, and
cut, strip and reconnect all of them neatly.
I PROMISE now to always check the voltage at the large brown at the alt!! IF
so I would have found that it was always 14.5V, even when the red ignition
light was on!!
Thanks again Paul and Pete (good idea that ground strap!!)
Tim
1969 MGBGT mona
----- Original Message -----
From: Tim Economu
To: paul.hunt1@blueyonder.co.uk
Sent: Thursday, October 09, 2003 5:09 AM
Subject: Re: MGB alt question
Thanks Paul....I'll try your suggestions in the am. My gut feel is a
connection on the engine, maybe the solenoid, since the symptom comes and
goes with the movement of the engine. I have confirmed your first
suggestion, that the warning light goes out when the alt connection is
removed.
Thanks again, and I'll let you know what worked !!
Tim
-------Original Message-------
From: Telewest \(PH\)
Date: Wednesday, October 08, 2003 02:23:41
To: Tim Economu
Cc: MG List
Subject: Re: MGB alt question
12.5/12.6 is definitely not charging. 13v plus shows some charge,
but it
should be more like 14.5v. The warning light glowing shows that the
brown/yellow at least is connected to something, to make sure that
it is
connected to the alternator and not grounding somewhere remove the
plug from
the alt, turn on the ignition, and check that the warning light no
longer
glows.
Check that you have 12.5v or so on the browns at the alt, ignition
off and
engine stopped. Start the engine and rev it to at least 1000rpm, and
check
the voltages on the brown(s) and brown/yellow at the alt. You should
have
about 14.5v on both. If still 12 point something rev it to about
3500 rpm
and check again. If now 14.5v it does indicate that there is a
problem
inside the alt. If still at 12 point something volts check the brown
and
brown/yellow wires in the wiring plug are connected to the correct
spades on
the alt, there are connection differences with some alts.
If you have 14.5v at the alt but only 13v or so at the fusebox then
you have
some bad connections. Check at the solenoid (each spade or lug
individually
while they are still all bolted/connected together) and the battery.
You
may find different voltages on each brown at the solenoid which
indicates
bad connections either there or at the alt.
Other than that the warning light glowing shows it has more voltage
one side
than the other. With the ignition off you have 0v both sides so it
doesn't
glow. When you first turn on the ignition you have 12v on the white
side
and 0v (ground) on the brown yellow so it glows. When the engine is
running
and alt charging you should have about 14v both sides so again it
doesn't
glow. When you turn off the ignition and while the engine is still
spinning
down you have 0v on the white and 14v on the brown/yellow so it
glows again
but flickers and dies as the engine stops. The warning light glowing
while
the ignition is on and the engine spinning at over 1000 rpm
indicates that
either the voltage from the alt on the brown/yellow has dropped
below or
risen above 14v, or the voltage on the white has dropped below 14v.
You
need to have a test-meter hooked up to first one then the other to
see just
what is causing the light to glow while driving before proceeding
further.
PaulH.
----- Original Message -----
From: "Tim Economu" <teconomu@whidbey.com>
To: <paul.hunt1@blueyonder.co.uk>
Cc: "MG List" <mgs@autox.team.net>
Sent: Wednesday, October 08, 2003 6:41 AM
Subject: MGB alt question
Hi Paul and all:
Wondering if you would have a moment to help me with my charging
problem. My
ignition light sometimes comes on, and sometimes goes off when the
engine is
running. My great MG electrical experience told me it was the alt,
so I
changed it out with a tested rebuilt unit (tested good to 38 amps),
and same
symptoms.
Here's what happens...
1. Turn on switch, red ignition light on. Vbat = 12.6
2. Start motor. Red light still on. Vbat 12.5
3. Rev motor, light still on until the motor... Vbat 12.5
4. Decelerates, light goes out. Vbat 13.6
5. Motor decelerates to idle. Light still out , vbat 13.0
6. Motor accelerates, light comes on, Vbat 12.4, then deceleratees
and light
goes back out, vbat 13.5.
I am considering a loose connection in proximity of the engine, so
that it
flexes with each accel/decel cycle. Is there a specific wire I
should be
checking, or should I consider anything else??
Kind Regards,
Tim Economu
1969 MGBGT mona
.
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