Strange fungus-looking stuff on car battery


Old 05-09-14, 04:14 PM
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Join Date: Jun 2013
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Strange fungus-looking stuff on car battery


I own a 2001 Honda Accord. Today it wouldn't start; seemed like it wasn't getting any juice from the battery. Popped the hood and saw this weird brown fungus-like crap all over the battery (around the + node), along with some other light blue stuff. Not sure what it is, why it's there, or if I need to be concerned about anything. Mainly I'm just wondering if this is a symptom of a larger problem.

I've attached a couple pictures.

Car battery - Imgur

Thanks for your help.
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Old 05-09-14, 05:39 PM
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Thats typical terminal corrosion...theres a name for it...some sort of oxide?

Wash it off with a cola (Coke, Pepsi, RC...whatever) and a brush. I think vinegar works as well? Rinse with water.

Remove the battery cables and clean the post, clamp, and hardware with a small wire brush or battery terminal cleaning tool (cheap at any auto parts store). Reattach and smear with vasoline or spray with an anti-corrosion product like chain lube. They make specific products for it as well as little impregnated felt washers that you put under the clamps to prevent this. It also helps to keep the battery top clean.

How long have you been driving? You've never seen this before?
Old 05-09-14, 06:07 PM
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Mainly I'm just wondering if this is a symptom of a larger problem.
That is a symptom of a much larger problem, Lack of Maintenance!
Old 05-09-14, 06:17 PM
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I really think we need a mandatory high school class in day-to-day living. How to replace a light switch, how to do routine maintenance on your car, how to make a simple stew, how to wash your clothes and that sort of thing.

Gunguy, you wash the smut off with a solution of baking soda and water, making sure to NOT get any of the solution in the battery cells. Since it was formed from acid vapors (from the vents from the filler caps) you need to use an alkali substance for cleaning. It will foam up and bubble when you do it. You should wear long sleeves, rubber gloves and safety glasses at the least and if you want to use a wire brush I would strongly suggest a full face shield to prevent getting any of the smut on your face. I have never used cola for this so I don't know if it will work but I doubt it as cola contains a minute amount of phosphoric acid and you need an alkali. When you get done rinse off everything with flowing water.
Old 05-09-14, 06:24 PM
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Blue "fungus" is CuSO4. Copper sulfate. Red fungus is Fe2O3, iron oxide. Amazing how folks expect car to start with such chemical display on battery.
Old 05-09-14, 07:12 PM
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Furd...Cola works great. Try it some time. Don't forget it has carbonic acid as well as phosphoric. I'm sure the baking soda does as well, but unless you are home...might be hard to come by. You can get a cola from a vending machine in front of a closed grocery store.

Btw..the white stuff is lead oxide (which reacts with both acids and bases)...and the red is just rust (iron oxide as mentioned) caused by the bolts and nuts bleeding over into the lead oxide. Quality cables where the copper wire isn't very exposed won't show the blue stuff that much, it's just enhanced verdigris basically, due to the presence of the acid fumes. I think it's actually more like a copper carbonate (which would react with an acid), but I'm no chemist. (Where is our chemist Pro anyway..haven't seen him in a while.) You see a lot of it with the replacement clamps where you have to strip the insulation back and the strands are exposed.

We used to soak brass and copper items that were all blue green from verdigris in a bucket full of concentrated "bug juice" (generic koolaid) in the Navy. Very high in citric acid. Soak over night and all the stuff is gone.
Old 05-11-14, 11:03 AM
Thread Starter
Join Date: Jun 2013
Posts: 5
Thank you all for the helpful and informative replies.

After cleaning, it seems I'm going to need some repairs. Is this the kind of repair I can do myself, or do I need to have the car towed into the shop? If the former, what is the name of the part that I need to go buy? Any other tips?

More pics: imgur: the simple image sharer

Old 05-11-14, 11:26 AM
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Why would you need repairs?

Ohhhhh...just looked at the new pics. You just need a replacement clamp.

Clean everything up (leave the battery caps on) then rinse with water. Pull the caps off the battery fill holes (the things that say danger/poison), look at the water level inside. It should be at the bottom of the little "tube" that extends from the top of the battery. Most have a slot on the side so you can tell the level. If you can see the rows of plates inside...thats bad. It means the battery may have been run dry or was being overcharged and the fluid was boiled off. The fluid inside is a mix of acid and water. If it is slightly can top it off with distilled water. DO NOT use tap or bottled water. Don't overfill...just to the bottom of the slot.

You'll need to go to a auto parts store and buy a new clamp...just a few bucks. The parts guys can explain how to attach it. Get a battery terminal brush while you are there. Strip an inch or so of insulation off the cable then attach the new clamp. If the cables are held/crimped together somehow...just clean them up as good as possible and put in the new clamp. You may not be able to use the red rubber boot on the new clamp.

After all this, the car may start, or it may need to be jumped. Ideally, you should take the battery out and have it tested (free) at the parts store. That will eliminate another trip if it turns out to be bad.

Last edited by Gunguy45; 05-12-14 at 09:39 AM.
Old 05-12-14, 09:26 AM
Join Date: Apr 2014
Posts: 115
Also keep in mind that the average battery won't last much more than about five years. Most batteries will have a date code and/or purchase date sticker placed somewhere on them. So, if it's more than 4-5 years old, you may want to consider replacing it regardless of whether it "tests" good. Old batteries will often fail to hold a charge for more than a few days as opposed to a newer battery which will often hold a charge for more than a few weeks or so when not in use.

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