Why do car batteries corrode?

I noticed some greenish build-up around my car battery’s terminal recently, which I’m assuming is corrosion. I thought I took pretty good care of my car, so I don’t understand why it’s there. Why do car batteries corrode?

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Answer provided by
Kathryn Mae Kurlychek
Answered on Jul 14, 2022
Battery corrosion is easy to identify with its white, blue, or greenish hue, but it’s a little harder to understand. Batteries corrode when liquids or gases escape from your battery over time, reacting within the ambient atmosphere under your hood.
Sulfuric acid and hydrogen gas are both common culprits of battery corrosion and typically react to (and damage) the metal components of your battery, including your battery terminals.
If you’re not charging your car’s battery enough, you will likely see corrosion, particularly on the negative terminal. On the other hand, if you’re overcharging your battery, you’ll probably run into corrosion on the positive terminal.
Unfortunately, corrosion is likely to occur over time no matter what you do, but you can apply anti-corrosion products to your car’s battery to help curb the process.
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