2004 Accord coupe: Proper charging voltage

The system design to protect iron/steel with sacrificial zinc
does not need electricity from car battery to work...

So the gizmo I have in my honda would work on some different principle.

 

that's correct - the zinc corrodes preferentially to steel. and the
process still needs electrolyte immersion.

yeah. it extracts the electrons from the dollar bills in your wallet
and having thus determined their coordinates, the gizmo's vendor can
then teleport those bills, your credit card details and your wife's cell
phone number into their own private possession without your knowledge.
it does damn-all for rust protection on your car.

 

Yes, it needs electrolyte, but it is everywhere...
Rain, road puddle with water, melting snow with salt, etc.

Zinc plating (galvanizing) is used for many other iron/steel applications
where rust resistance is needed which are not water-immersed.
Compare wire fence, steel tube, angle iron or I-beams.

Similar situation i with tin-plating. It provides sacrificial protection
for copper, nickel and other non-ferrous metals, but not for steel.

Product does not need to be submersed in water for this principle
to work - if there is enough moisture in the air to cause rust than
sacrificial zinc layer should work just fine...

BTW - is accord build with zinc-plated/galvanized steel?

Well, I got this car used with gizmo installed already, so I did
not spend a penny on it.

 

I think so. But zinc eventually "wears out" when its anodic protection is
used up.

Rust is a process that involves electrons flowing out of iron (in the
steel). The electronic rust-proofing systems use that as their basis for
justification. Somehow, causing elelctron flow to occur in the electrolyte
is supposed to interfere with electron flow out of the iron.

I'm no chemist, but I can't see how electronic rust-proofing could possibly
work. The car's body already has lots of electrons flowing through it. It's
the ground for the car's 12V electrical system, remember?

A wire that carries electricity will rust just the same as one that does
not carry electricity, provided that wire is made of a corrodable substance
(like iron or copper). Electrons in the electrolyte do not protect metal
from corrosion.

The only way to prevent corrosion is to prevent oxygen and steel from
meeting in the first place. That means zinc primer with paint, or chemical-
based rustproofing.

I don't think it will /hurt/ at all, it just won't /help/. The hurt may
eventually come in the form of electrical trouble at the aftermarket
splices into the factory wiring. But that's true of any aftermarket device.

 

but it needs to form a continuous electrical connection so that all
regions have the same electrode potential all the time. rain splashes
are not continuous immersion and a sacrificial anode doesn't work.
don't take my word for it - try it yourself.

but that's a zinc layer [galvanizing or sherardizing] - different
principle! a sacrificial anode will protect naked steel - sherardizing
or galvanizing are simply plating processes.

i believe parts of it use sherardized steel, yes.

good luck.

 

that would be correct, but in the same way as a sacrificial anode, it
requires full continuous electrical immersion int he electrolyte to
work. patch wetting doesn't work as local electrode potential cells
establish themselves and corrosion marches away as normal.

 

Is there any place we could check it to know for sure?

Understood. Nothing will last forever.
We are comparing here steel protected only with paint
to the steel protected with sacrificial layer of zinc
and the paint. The second will last significantly longer.
And no electronic gizmo is needed for this purpose.

Corrosion happens on the borders of two metals, including mixtures
of metals (like steel). I am talking about micro borders in crystal
structure of the metal. No metal is pure and will have mixture of
different metalc causing forming micro-cells for electricity to flow.

If a car panels are mad of galvanized steel - paint works as
a rust/oxidation protection of the zinc layer... Rust will
act on the zinc layer first, if paint layer is comprimised.
Zinc layer will then prevent corrosion of the steel with
the sacrificial anode principle. Rain/snow will connect
the steel-zinc contact and will cause zinc to rust first.

 

Same principle, different implementation of the principle.
When it is not practical to use galvanized steel you can
use sacrificial anode made with chunk of zinc - when this
is used up you can replace anode and continue protection.
With products made of the galvanized steel, the principle
is the same, there are just practical differences, like
you cannot "replace" sacrificial anode because it is
under the paint, covering your whole care for example.
Both work the same way.

Parts? Not all panels?

 

Continous immersion is required only in case of situation
you have in a ocean boat. Electrolitic current flow has to
take place between remove iron component and the single
sacrificial zinc anode. Without electrolitic link proces stops.

With galvanized steel you have to think in a micro-scale.
Each spot with chipped paint cover lets the oxygen and
water into the contact with bare metal. If steel would not
be exposed and zinc layer is 100% sealed, only zinc will
oxidize and we have no sacrificial anode principle in
working here...
Situation in real life is different - no layer is 100% seal.
There will be always pores in zinc layer, exposing steel.
So, the micro-hole in the paint and zinc layer will be exposed
to air (oxygen) and water (not pure water, rather electrolite).
And on the micro-scale zinc layer will start to sacrifice
using the same principle as with the boat and remote anode.

 

This is great territory to get in a pissing contest.

Suffice to say that "electrolyte" has different values depending on
environment. Emersed simply brings about faster reaction, (similar to
plating etc.), as opposed to atmospheric which simply allows oxidation,
(rust to most of us).

The value of no charged zinc based components, (pot metal is a prime
example), are the first to deteriorate. And, that deterioration is
partially blocked by chrome plating but once it begins to blister,
(pit), the show's over.

Just a note... Back in the "old" days most cars had positive grounds
which also minimizes oxidation since electron flow is reversed. I
sometimes wonder why they ever change to negative ground especially in
the the rust belt...

JT

 

sorry, that's not the complete story. in order for that sacrificial
anode to protect, there has to be a direct electrolyte-born current path
between the anode and the cathode. if the electrolyte is not in full
contact with the cathode, the cathode cannot be protected, it's still
subject to corrosion. and the only direct electrical path available is
with electrolyte immersion. patches of discontinuous electrolyte [rain
splashes] are not electrically connected with each other and thus there
is no protection current.

the bits that get salted the most. not much point for the roof.

 

Jim, in case of the galvanized steel you have direct electrical
path available between two metals (steel and zinc) in every
place where you have a pore in your body paint and a rain drop...
If you have car made of galvanized steel, whole car submersion
in electrolite is not required for the zinc to work.

Read my other post in this thread and you will understand that
naked steel + zinc anode attached and galvanizing are simply two
implementations of THE SAME electro-chemical principle.

 

They might be, but they don't operate in the same environments.

Imagine a car door. There is water in the bottom of the door, but not
anywhere on the vertical walls of the door. There is no connection between
your chunk of zinc and the bottom of the door. The door will rust no matter
what.

Zinc sheet covering the inside of the door is in direct contact with the
water in the door bottom. It will function until the zinc is used up.

 

no, that's not correct. galvanizing or sherardizing are /not/ the same
as sacrificial anodic protection. with the latter, you can have a
huge-ass ship-sized chunk of naked steel, contiguous electrolyte, a
sacrificial anode, and no corrosion in the steel. the anode corrodes
like the blazes. IT DOES NOT WORK if the electrolyte is not contiguous
because the electron flow generated by the anode electrolysis is not
transmitted to the areas not contacted with contiguous electrolyte.

with galvanizing and sherardizing otoh, you have contiguous plating
which protects in /two/ ways. first is [comparatively] passive plating.
second is a localized electrolytic cell disruption. this works with
or without liquid electrolyte.

so, getting back to cars, a lot of modern vehicle body panels are
sherardized, and this gives the passivating protection you're seeking to
establish. but you CANNOT achieve this same effect by bolting a bit of
zinc onto the chassis of a car and have it protect the whole vehicle
unless there is contiguous electrolyte. even in seattle in the depths
of winter rain, they don't have that. and getting back to the op's
doohickey, it's a total waste of money, and designed by someone with
insufficient understanding of corrosion principles.

 

Same principle does not mean that they will operate
in the same environments. Of course a naked iron boat
with an anode in a form of a chunk of zinc will be
immersed in sea water so there is no need to have
zinc close to every part of iron...

In case of galvanising you have the same electrochemical
process going on but on a micro scale, micro-distances.

We are discussing a situation where you have a dent in the paint
surface, so there is a gap in the paint seal. Water wets the bare
metal and causes electrolitic link between metals on micropores.
All this apply to galvanized or zinc plated steel panels or
similarly protected suspention parts.

Nowhere in my post I was comenting that their gizmo will work...
I am still interested in how it supposed to work and what is
the principle used there... Why do we need electrical current, etc.
I was comenting galvanized panels as sufficient because working
on the same "Sacrificial zinc anode" principle.

 

zinc plating is /NOT/ sacrificial anode principle!!! it's surface
passivation! no electron flow!

again?

 

It is true, untill the zinc layer is broken... Paint is also
passivation layer, untill the paint is cracked and
metal underneath is exposed to weather elements.
At this moment paint stops working, zinc layer
continues to work on the anode/cathode principle
and will be used up first before steel starts to rust.
That is why zinc plated steel pieces can survive
without corrosion for 70 years - try this with paint!

Couple of quotations from the expert sites as a backup
to my words:

http://en.wikipedia.org/wiki/Galvanization
Zinc coatings prevent corrosion of the protected metal
by forming a physical barrier, and by acting as a sacrificial
anode if this barrier is damaged.

http://www.galvanizeit.org/showContent,26,58.cfm#1
1. How does galvanizing protect steel from corrosion?
Zinc metal used in the galvanizing process provides an
impervious barrier between the steel substrate and
corrosive elements in the atmosphere. It does not allow
moisture and corrosive chlorides and sulfides to attack
the steel. Zinc is more importantly anodic to steel -
meaning it will corrode before the steel, until the zinc is
entirely consumed.

http://www.wisegeek.com/what-is-galvanized-steel.htm
Zinc also protects the steel by acting as a "sacrificial layer."
If, for some reason, rust does take hold on the surface
of galvanized steel, the zinc will get corroded first.
This allows the zinc that is spread over the breach or
scratch to prevent rust from reaching the steel.

 

Check my quotations from the other post.
They specificaly use the term "sacrificial anode" in galvanized steel.

I have never stated in this discussion that you can achieve the
same by bolting a chunk of zinc to a car... You do not need to
do it. However, if you have zinc plated panels you are protected
by the zinc layer on the same principle.

Do you know the design details of this doohickey?