A charged battery that sits, will sulfate the plates.. That is...
the chemicals in the battery liquid will slowly drop
out of suspension and attach themselves to the plates
of the battery. Over time, this reduces the capacity
of the battery. A battery at rest (an hour or two of no
charge being applied) voltage level can identify it's
'capacity' capabilities as follows
volts specific gravity capacity
12.6-12.8V 1.265 100%
12.4-12.6V 1.225 75-100%
12.2-12.4V 1.190 50-75%
12.0-12.2V 1.155 25-50%
11.7-12.0V 1.120 0-25%
Your situation sound like at least one cell is starting to
loose it's 'capacity' capabilities.
A more detailed explanation of what 'plating' is all about
can be read at
http://www.uuhome.de/william.darden/batlinks.htm#desulfators
specifically Desulfators and Pulse Chargers
Paul Tegler
ptegler@cablespeed.com
www.teglerizer.com
----- Original Message -----
From: <Cyc10@aol.com>
To: <paul.hunt1@blueyonder.co.uk>; <mgs@autox.team.net>
Sent: Monday, August 02, 2004 12:20 AM
Subject: Re: Starter problem when hot
> Hi Paul and fellow listers,
>
> I finally had a chance to check my B out. I am storing it a couple
hundred
> miles from my house at a summer place.
>
> I ran the tests and found that the voltage on the resting battery was
about
> 12.5 V for several weeks took readings at battery posts, terminals, and at
> starter solenoid after car sat several weeks. Started car and voltage
readings
> read okay and the same at all these points.
>
> At idle voltage was around 13.5 V at all these points. Took car out for a
> long ride and came back and checked voltage. Turned car off and readings
around
> 12.5 (cannot remember exact amount). Tried to start car and voltage
measured
> around 10.5 volts at all of the points and starter was sluggish. Let car
> cool down and all values returned to normal and it started right up. Will
keep
> you advised. I guess I will look further into the starter.
>
> Forgot to tell you that the car will start after getting it rolling and
> engaging the clutch. I also ran a current leakage test and no leakage and
the
> battery checked out okay.
>
> Cheers and thanks
> Al
> 60 A coupe resting, 62 A MKII rd running, 65 S type 3.8 Jag resting, 70
mgb
> rd running.
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