[Vwdiesel] More on radiator as a battery (weekend science thread)

[Mark Shepherd]

Paul thanks for the reply.

My brain storming lies in the doubt of what kind of circuit
we are dealing with....
If the coolant is the lemon and the rad is one terminal and
the engine/chassis is the other,
 then the circuit is open with a dilectric/insulator being
the rad mountings/plastic frame.
Maybe current flows when the insulators become contaminated
and conductive...
The interest in the static created when we climb out of our
vehicles in our 'silks' is that if it is created
 but doesnt discharge through us to ground could it help in
'bridging the gap' or insulation of the rad;
 my mind being focused on the fact that all charged
capacitors discharge over time and if we keep charging the
car up every trip...

Maybe two identical cars one with earthing strap dangling on
floor and one without may have different rad corrosion???

How long before a new rad develops a voltage?
Does changing the coolant stop the voltage?...
If so then its all about regular changes of coolant to save
the rad and the voltage of 0.3V is not a measure of rad
corrosion;
but a signal that the rad is corroding and so a slight
exaggeration by the rad seller to sell more rads is not
impossible.;o)

Anyone put a new rad in old coolant? And left it for a
period so we can get a reading...

Mark-The-Miser(UK)


----- Original Message -----
From: paulr <reichp at earthlink.net>
To: Mark Shepherd <mark at shepher.fsnet.co.uk>
Sent: Friday, November 05, 2004 3:07 AM
Subject: Re: [Vwdiesel] More on radiator as a battery
(weekend science thread)


> Mark Shepherd wrote:
> > This radiator voltage that can be measured when the rad
is
> > 'decaying' ...Is it current driven ie voltage drop
across a
> > resistance?...Or is it 'capacitive'
>
> The voltage is a "battery" effect.  Voltage comes from a
reaction
> between aluminum, iron and acidic coolant. Same thing as a
lemon,
> with copper and iron electrodes stuck in it.
>
> If it's possible to measure voltage between the rad and
the
> body ground, I'd think there is a problem with acidic
coolant.
> Won't have a voltage (corrosion) without acid somewhere.
>
> >
> > What about deliberately creating a reverse voltage to
> > 'replate' the rad with the ally that is in solution.
>
> Definitely can replate with "too much" reverse current.
Can't
> control *where* the replating occurs. Replating occurs
where
> current *density* is highest. Mostly at sharp edges.
Usually
> forms dendrites and thin filaments, randomly located.
>
> Ironically, the spots where Al corrodes tend to repel
current,
> and replating occurs ELSEWHERE!  :-(
>
> >
> > Are there any links to the  zaps of static we get from
time
> > to time when exiting the car and rad corrosion?
>
> Not related to corrosion. Spark has too little current,
and
> doesn't create continuous voltage.
>
> Static "zaps" are two different *insulators* (cloth and
vinyl)
> rubbed against each other. A Van Degraff generator is
another
> example. Can't get steady current from that, just short,
small
> sparks.
>
> Static electricity never happens between 2 metal parts.
What you
> see are showers of molten metal flying about, from
friction and
> high temperatures ( > 1000C ).
>
> Might try www.howthingswork.com and look around for
subjects
> like static electricity, Van DeGraff generator, galvanic
voltage,
> rust, corrosion, chemistry.
>
> Combustion gases from a leaky head gasket speed up
corrosion.
> Put some fresh coolant and *distilled* water into the
system, and
> the voltage should vanish, at least for a while. Voltage
test is
> a good way to tell when it's time to change coolant.
>
> Plastic end tanks and gaskets are my biggest radiator
problems.
> Shitty design. Might try pulling the rad someday, and
re-crimping
> the edges of the core....  'Nuther subject altogether
<grrrr>
>
>
> HTH,
>
> Paul
>
> >
> > Miser
> >
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> >
>
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