Stupid Automotive Question: What causes this?

[N80]

I know what this is and how to clean it up but I don't know why it happens. I've had this car for 5 years and this has never been an issue. I think the battery is a cheap AutoZone or Advanced Auto Parts. I've found them to be short lived and low quality.

Anyone know how to prevent this?

I know they make those little foam washers for this but back in the day those never worked.

 

[Mendonsy]

That looks like a combination of a battery that leaks around the post and a poor cable connection. About the only thing that works to prevent that corrosion is a heavy coat of grease over the terminals after making the connection. A mixture of baking soda and water will help to clean up the mess that you have.

 

[LittleBill21]

I know what this is and how to clean it up but I don't know why it happens. I've had this car for 5 years and this has never been an issue. I think the battery is a cheap AutoZone or Advanced Auto Parts. I've found them to be short lived and low quality.

Anyone know how to prevent this?

I know they make those little foam washers for this but back in the day those never worked.

View attachment 516095

those washers with the oil have worked well for me, they are now on every car i own.

 

[drssg]

IME, it's due to a poor quality battery. For the original battery in my tractor, I never got around to greasing the battery terminals, but I didn't have a problem with corrosion.

The next battery was a cheap one from TSC. It gave me chronic issues with corrosion, even though I periodically cleaned and greased them. By the time I replaced that battery, I also had to replace a cable, due to corrosion.

After that experience, I paid extra for an Optima battery. It's been going strong for quite a while, with no corrosion issues.

 

[RNeumann]

That looks like a combination of a battery that leaks around the post and a poor cable connection. About the only thing that works to prevent that corrosion is a heavy coat of grease over the terminals after making the connection. A mixture of baking soda and water will help to clean up the mess that you have.

Second- batteries off gas a little acid which can "react" with objects around it. The baking soda helps neutralize the acid. Grease (I actually prefer Vaseline since they used it in aerospace) puts a layer or barrier between the acid from the battery and the metal the acid is attacking.

This is my chance to "plug" sealed batteries. They cost a bit more up front but between longer life, decreased maintenance and the decreased damage it may be cheaper for some in the long run.

 

[N80]

I did the baking soda and water routine and it worked well, as usual.

For a while, maybe 20-25 years ago, all my new cars came with sealed batteries. After that, I probably haven't seen a sealed battery since. I didn't even know you could still get them.

How about dielectric grease? I've got a big tube of that.

 

[Mendonsy]

Dielectric grease is probably OK, but it won't help with the cable connection because it is non-conductive. What you are trying to do with the grease is to keep the acid and fumes away from the metal parts.

 

[Oaktree]

Guess I've been lucky. Haven't had that happen in ages. The again, I try to avoid el cheapo batteries.

 

[dstig1]

Clean it up with baking soda/water paste first (or even just a wet paper towel), then get a can of battery terminal spray. Hose down the terminals and any exposed bare metal in the area (tray, hold downs, etc). Respray periodically like when you change the oil. No further problems.

It is corrosion from battery acid.