Anti-corrosion car module BS or not?

[edy]

Hi guys,

I was at my car dealer and they offered a rust protection package that included the "corrosion module" you see in the attached image. Anyone know if this actually works, partially works, works in theory only, or is complete BS? I thought the car chassis is a common to the negative on the battery. How is this thing supposed to work if it is hooked up to your battery as well?

I guess electrochemically it is supposed to affect salt from interacting with the iron. When you throw salt in a cup of water and have two electrodes, the salt ions allow current to flow and you get electrolysis of water into hydrogen and oxygen bubbles at the electrodes. I assume the theory is that salt on the car with water and the negative chassis charge may somehow conduct but where is the circuit here? I'll need to refresh my chemistry but I wanted to see if any of you have seen this and what merit it has.

Maybe if this is "flaky" even Dave could chime in with a bull$h!t smell test or a teardown if we can get him one of these modules.

[edy]

These were promoted by my Honda dealer but I see others prominently advertising these in my area:

http://www.donvalleynorthlexus.com/coverage/protect-your-investment/corrosion-control-module

There is a video at the above link but somehow my BS intuition is telling me something is not making sense here... yet they are being sold to the scientifically uninformed public as science.

[SeanB]

Basically they use a green LED supplied via a resistor from the battery to make a 2V reference, and this is supplied ( via a resistor) to 2 strips of conductive carbon black loaded plastic strips that are stuck to the underside of the car with some double sided insulating foam strips.

Tried in the 1970's ( as far back as I can see the ads in Car magazine) and it basically does not work in real life, though the theory is somewhat right.

[ConKbot]

Complete BS. Cathodic protection works when the metal you want to protect is one electrically conductive medium. I.e. on boats, you have a steel hull and all the moving bits get electrically bonded to the hull, throw on a few zinc anodes, electrically connected to the hull if youre doing passive, or insulated and connected to a power supply (referenced to the hull) if youre doing active protection. You make a single electrochemical cell, and the whole thing is protected. 

With a car, get a bunch of salt spay on the underside, and you have thousands of droplets on the car, each one corroding the metal in its own little chemical reaction.

At least underbody coatings are somewhat reasonable logically, even if they are crap in practice, now dealerships are pushing BS 

[edy]

I read up on ICCP (Impressed Current Cathodic Protection) and it needs a circuit to function. The reason it works on boats and bridges is that it uses either water or soil as an electrolyte to complete the circuit, and essentially turns the object you are trying to protect into a cathode (reductive reaction ) and a sacrificial metal into the anode (oxidation).

The only way I see this working at all is if your car is immersed in water, or makes constant contact with moist soil... in which case the wiring would have to be make the car a cathode (negative terminal?) and stick the positive into a sacrificial anode into the ground or water... and maybe if your car surface somehow makes contact with the ground/water for a brief moment it allows some current to conduct and allow the reactions to occur. This really only seems to work with objects in water or making contact with soil, otherwise no circuit is closed as there is no electroyte.

Most cars are covered with zinc now anyways which makes that the sacrificial anode. If you want to force it more with ICCP, perhaps wire up the battery to contact the thin zinc plating and the other terminal to contact through the zinc directly into the steel iron, make sure you have polarity correct to make the iron a cathode and zinc the anode. Normally these metals will set up their own galvanic cell and give you the correct anode/cathode relationship which is why zinc is used to protect the iron.

These corrosion protectors either are not wired properly to function as ICCP (anode/cathode to zinc and iron) or have no obvious circuit path to allow any kind of current to flow, which is needed if we are to draw electrons out of one metal and deposit it into another (reduction/oxidation).

What I am amazed at is the microprocessor sophistication of the latest devices (so claimed) and also fervent marketing by dealers who either have no clue it is bogus or know but don't care because they just to make a magin/commission.

I wish Dave could take apart the latest "microprocessor" driven one and measure the output and debunk the myth.

[edy]

I found they sell them in stores too:

http://www.canadiantire.ca/en/pdp/counteract-electronic-rust-protection-system-0477905p.html#.VVQwzTgpDHw

$300... ouch!

Here is the patent for this device:

http://www.google.com/patents/US4767512

At least they didn't lie about having a patent.

I've taken the liberty of including the patent schematics here (see attached).

[T3sl4co1l]

Guaranteed?  I'd like to see the terms of that warranty...

[Delta]

Complete and utter bullshite. Won't work and can't possibly work.
I have worked on ICCP and other corrosion & growth prevention systems on boats, but to claim such a system could work on a car is nonsense.

ps. I do like nice swirly current paths shown in their picture...

[george graves]

Water heaters have a "sacrificial rod"  So kinda of the same.

But back in the day, cars would have +12 volts to the body, and ground would be run IIRC.  And that is a good way of getting rust I would think.

[edy]

Thanks for the feedback... Yeah my suspicions were correct. When I was at the dealer (buying out my lease) he wanted to sell me all these "protection" and warranty packages. As soon as I saw the brochure and he told me how he has one, and his friend has one, and he swears by it... my BS detector just spiked. But I didn't want to argue with the guy without doing my research first.

Nevertheless, I am amazed they are pushing these things still and that consumer protection hasn't done an expose or brought it to the media at least a few times a year to continue to remind people it is a scam. I have university science degree to help me detect this stuff, but what do most consumers do?

If the dealer has no idea, I wouldn't fault them. However if they know it is crap and still try to sell it I have lost all faith and trust (probably shouldn't have had any with them to begin with).

[jolshefsky]

In 1994 I bought a new Honda and had the electronic anti-corrosion system installed. It started rusting like normal and I eventually called to have the "lifetime warranty" honored. Alas, the original company was gone. My suspicion was they would set up shop, sell a bunch of units, then dissolve and reform a new company every few years.

In any cases, I did take pictures of the unit from the car in case you wondered how it worked. I never did bother sketching a schematic, but it looks dead simple. Basically red is +12V, black is ground, and each white wire would go to the contacts stuck to the shock towers. The green light would stay on and the red lights would alternate if I remember correctly.

[edy]

That's fantastic... Thanks for sharing! Maybe we can DaveCAD the schematic to see what is going on. Did the LEDs blink? I wonder if all we are seeing is some resonating circuit designed to blink the LEDs. The white wires went to the shock struts? Black and red went to battery terminals I assume? Will be interesting to see what the schematic reveals once reverse engineered.

[xygor]

It's BS.  What's the current path?  And in that path, what is the anode?  The anode needs to be something that is easily replaceable because it will corrode.  Or it needs to be some exotic material such as graphite or mixed metal oxide coated titanium.

[JDS]

Corrosion was a big problem in the 70's but not so much today. Now most cars have a significant amount of corrosion resistance designed into them (paints, primers, coatings, undercoating, sacrificial coatings, plastic fasteners and plastic parts where corrosion is most likely).  I have a 15 year old forester with no rust and I live in Minnesota where they use plenty of salt.  In short they are charging you a hefty priced for a set of suspenders to go with your belt.  Save the money and take your wife out to dinner 4 or 5 times.  You'll get a better bang for your buck that way.

[TimFox]

There is a good discussion of rust in general, in the recent book:
J Waldman: "Rust, the longest war" (Simon and Schuster 2015) ISBN 978-1-4516-9159-7.
See pp 256-260 about galvanic corrosion scams.

[McBryce]

In any cases, I did take pictures of the unit from the car in case you wondered how it worked. I never did bother sketching a schematic, but it looks dead simple. Basically red is +12V, black is ground, and each white wire would go to the contacts stuck to the shock towers. The green light would stay on and the red lights would alternate if I remember correctly.

Hilarious. Here's the schematic. Obviously way above my head, because they seem to have hidden the "magic" in there somewhere and I can't find it At 300 dollars I suspect they used Unicorn tears or ionised hens teeth to achieve their goal.

McBryce.

[edy]

Yes, what upset me the most was this was my own Honda dealership in Toronto (Sisley)... one of the largest in the region. Surely they must know it is crap but yet still choose to offer this 3rd party rust proofing option for the extra commission. Makes me sick!

[G7PSK]

Corrosion was a problem in the 60's and 70's due to positive earth systems used on most cars when that all changed to negative earth corrosion was not such a problem any more and by the 80's car manufacturers were also using more effective protective coatings. I would be very wary of any device that requires an electrical connection to the body work other than those using the grounding points built in during manufacture as that would involve removing the protective coatings.

[amyk]

I've taken the liberty of including the patent schematics here (see attached).

Here is your word of the day: a "holiday" is also an "unintentional gap left on a plated, coated, or painted surface."

You may find this slightly amusing.

[gildasd]

It rained a lot yesterday, so I measured the conductivity of the underside of my car.
In the name of science.

So after one hour on drenched motorway, it's less than a meter (Mohms or no detection) and often around 50cm.
I imagine that with slush and salt this would go up a bit...
In any case I would need 6 to 8 modules... I think it's cheaper, easier, more effectiveto spray a coating of anticorrosive (in Europe at least).

[SeanB]

Spray the coating, works better than the snake oil. If doing that you first use a spray gun ( known in the spray paint trade as a paraffin gun) to put a mix of 80% boiled linseed oil and 20% paraffin/kerosine/jet fuel into every box section of the vehicle, removing all the plastic caps if present. That will provide a very good corrosion barrier, and stop existing corrosion inside from eating through. You do need to have the underside clean, preferably using high pressure washing with detergent and a high pressure rinse. It will drip for a long time afterwards, you will need to have a big cardboard pad where you park to absorb the dripping as the paraffin evaporates.

Messy, but an incredibly effective job for the cost. I did this to my last van, and after 10 years the little rust spot it had when I got it was still the same little covered spot, and I live in the corrosion capital of the planet. Plus it used to get driven into the dam every weekend with a boat, and spent a lot of time on the beach.

[gildasd]

Spray the coating, works better than the snake oil. If doing that you first use a spray gun ( known in the spray paint trade as a paraffin gun) to put a mix of 80% boiled linseed oil and 20% paraffin/kerosine/jet fuel into every box section of the vehicle, removing all the plastic caps if present. That will provide a very good corrosion barrier, and stop existing corrosion inside from eating through. You do need to have the underside clean, preferably using high pressure washing with detergent and a high pressure rinse. It will drip for a long time afterwards, you will need to have a big cardboard pad where you park to absorb the dripping as the paraffin evaporates.

Messy, but an incredibly effective job for the cost. I did this to my last van, and after 10 years the little rust spot it had when I got it was still the same little covered spot, and I live in the corrosion capital of the planet. Plus it used to get driven into the dam every weekend with a boat, and spent a lot of time on the beach.

I don't know if that's legal here!!!
In the South of France, a friend uses a black rubbery spray paint (Rubson?) for commercial vehicles:
The idea is to steam clean (without hitting the bearing and bushings), dry with compressed air, let it sit in warm dry place for 12 hours, apply.
This is not for moving parts, as your method probably is, but does protect the original coating from gravel scrapes etc.
Very effective but ugly at the junction between the sides and undersides...

[SeanB]

Not for moving parts, but for the chassis and subframe. Try to keep it off the exhaust, otherwise it really smells a lot when you start for the first few times, and the front by a catalytic converter might catch fire if you really coated it. It basically polymerises to form a coat that resists a lot of wear, and inside it keeps oxygen away from bare metal that never got coated in the paint booth and those spots where it was welded.

[McBryce]

I don't know if that's legal here!!!
In the South of France, a friend uses a black rubbery spray paint (Rubson?) for commercial vehicles:
The idea is to steam clean (without hitting the bearing and bushings), dry with compressed air, let it sit in warm dry place for 12 hours, apply.
This is not for moving parts, as your method probably is, but does protect the original coating from gravel scrapes etc.
Very effective but ugly at the junction between the sides and undersides...

There are many commercial "paint" spray versions available in Europe that will also do the job that well. Any decent car parts shop should be able to supply something.

Bryce.

[G7PSK]

That black rubbery substance is called underseal here you can also get a similar product in various colours for the bottom of doors and sills called anti stone chip. There is also a product called wax oil that is sprayed inside of panel's and doors to prevent corrosion. At one time such products were offered as extras on new cars but now it is not needed as the cars come pretty well protected against rust, most manufacturers offering ten year warranties against penetration by rust.