What causes the battery terminal connection on a car to corrode?

Well one is a negative charge and it just gives off bad vibes and takes everyone down.

Don’t batteries contain acid? I would think that’s a factor.

@Buttonstc Well, that’s the logical answer, but I’m sticking to the bad vibes from the negative terminal.

Oh, I just realized this is in Social :)

Yeah, I think you might be on to something.

I just remembered that the last time I bought a battery, the guy who installed it was super conscientious and placed these circular things over the terminals that look like washers. One red and one green. But they’re made of some type of felt, not metal as washers are.

And so far no corrosion. After reading your idea, I’m thinking that maybe the colors are what’s doing the job.

Red and Green are the traditional Christmas colors so that’s where the good vibes are coming from. Everybody loves Christmas :)

@Buttonstc Oh god, you had me laughing. I loved it. I think it is the acid and the electrical reactions. But I love your answer more.

Thanks.

Actually it’s quite logical. Out of all the colors they could have chosen, they picked red and green, Christmas colors.

Methinks that was not just coincidence :)

And the proof is there’s no corrosion :)

@rojo

You need to get yourself a set of those. I think they’re like $1 or something.

I will pass this on to my daughter, she was asking me about it. She took affront to the corrosion in HER car and wanted to know why the guys who had changed out her oil did not point it out to her.
I told her it had something to do with the acid in the battery but was not sure how or why it was able to form on the terminals when it was supposed to be inside the battery. It is a closed battery, one you do not add fluid to, which was my first guess, an overflow when it was being topped up.
Are there gasses that escape? Are they attracted to the terminals because of the charges being sent through the wires? Why one more than the other?

Now, both of you get serious. Don’t make me move this to General because I will, you know that! I will pull this question over immediately!

Because they’re politicians, like Trump, and they accept bribes.

@rojo There a lot of gases that escape, I guess just like Dutchess’s politicians. My uncle and I had one blow on us years ago. Fortunately it was the one behind us, or we’d have been hurting big time.

The cable end is usually made of copper, while the battery terminal is made of lead. Whenever you have 2 unlike metals in contact with moisture of some kind, you have corrosion. Car batteries are especially bad because of the acid in the electrolyte solution. The positive polarity of one augments the corrosion. Sealed cables (with a sealing solution, corn syrup, grease) keeps the air and moisture away from the connection, hence, less corrosion.

@Adirondackwannabe To quote Woodstock: ”...the brown acid that is circulating around us is not specifically too good, it’s suggested that you do stay away from that, course it’s your own trip, so be my guest, but please be advised that there is a warning on that, okay?”

Once upon a time, in the early 70’s, the Marquee thing for Century II, in downtown Wichita, got its letters switched around to read, “SMOKE POT AND EAT RAINBOW ACID.”

It’s generally copper sulfate and is caused by copper in contact with sulfuric acid in the presence of electric current and water.

Galvanic corrosion

One metal is literally falling apart and depositing on the other.

It’s an electrical phenomenon. It can happen with two dissimilar metals in simply in contact, but having an electrical power source involved accelerates it.

Wikipedia, which seems to cover every imaginable subject, answers the question under lead-acid battery:

Corrosion on the positive terminal is caused by electrolysis, due to a mismatch of metal alloys used in the manufacture of the battery terminal and cable connector. White corrosion is usually lead or zinc sulfate crystals. Aluminum connectors corrode to aluminum sulfate. Copper connectors produce blue and white corrosion crystals. Corrosion of a battery’s terminals can be reduced by coating the terminals with petroleum jelly or a commercially available product made for the purpose.[38]
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But here’s a completely different description from StackExchange:

Corrosion on the terminals is due to hydrogen gas being released from the acid in the battery. It mixes with other things in the atmosphere under the hood and produces the corrosion you see on the terminals. Generally, if the corrosion is occurring on the negative terminal, your system is probably undercharging. If on the positive side, it is probably overcharging. Most often it will be seen on the negative side because the battery is usually in an undercharged situation. This is just the nature of the beast, I’m afraid.
...
Your main objective is to keep the lead, escaped hydrogen gas, and oxygen from mixing which forms the corrosion you see after a period of time. Over time the grease will break down and corrosion may start…
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I found a site called Benign Blog that offers this:

In case of sealed lead acid battery (also known as SLA battery or dry battery), corrosion happens when electrolyte makes its way out to battery terminals through any leaks or joints. In case of flooded lead acid batteries (wet batteries), electrolyte can jump out while carelessly pouring water into cells. Also, fumes of sulphuric acid which is a part of electrolyte and actually responsible for corrosion keeps arising out of vents of flooded lead acid batteries when battery is charging or hot. Overcharging heats up the battery and heat increases the volume of electrolyte filled inside it. This electrolyte can leak out of vents of overcharged flooded lead acid battery…
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Why more at one battery terminal than the other? Seems it depends on which type of electrochemical reaction is happening.

Why only some cars? I’m not sure it doesn’t occur to some extent on all vehicles, but naturally newer cars have newer batteries. Maybe some manufacturers also provide better battery corrosion protections than others (terminal enclosures etc.) which is probably not an option for lower cost cars.

In my own experience once battery corrosion reaches the point of being obvious, it can quickly get worse in a runaway effect until the vehicle will no longer start. My guess is that decreasing metal contact area at the terminal results in increasing electrical resistance, which in turn leads to increasing heat, which speeds the breakdown of metal.

Great answers above. But does anybody know why a couple of pieces of felt-type material noticeably help?

It doesn’t make any sense to me why they would work but apparently they do. And they were certainly inexpensive enough and a much easier solution than scraping the corrosion off with a stiff wire brush (like the type used to clean BBQ grills) which I’ve used in years prior.

Obviously it doesn’t have anything to do with the colors :)

But what does it have anything to do with?

Well….it acts like a condom.

@Dutchess_III Really? I thought it more like a cock ring.

What the hell are we talking about?!