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What Causes Battery Sulfation and Corrosion?

Power - by Joe Weber - updated on 7/22/2024

car battery with corrosion

Battery sulfation and corrosion are major threats to your car battery's longevity and performance. While sulfation affects the battery plates, corrosion attacks the terminals, and both can lead to complete battery failure if not addressed. Let's explore what causes these issues and how you can prevent them.

What is Plate Sulfation?

As a lead-acid battery discharges, small sulfate crystals of lead and sulfur form on your battery's plates. This phenomenon is called sulfation. This happens to all lead batteries and is a normal part of the discharge process, reversed when the battery is recharged. If you leave a battery discharged for too long, however, this soft lead sulfate deposits on the negative plates, where it becomes hard, stable crystals that impede the battery's flow of electrical current and can be difficult to remove.

Can Battery Sulfation Be Reversed?

Sulfation can be reversed in a flooded lead acid battery if detected early enough. This is done by applying an overcharge to a fully charged battery using a regulated current of around 200mA (milliAmps) for roughly 24 hours. This allows the battery's terminal voltage to rise between 2.50 and 2.66 volts per cell, helping to dissolve the crystals.

Unfortunately, aside from tearing the battery down, it's very difficult to tell if your battery's performance is being affected by sulfation or some other cause as the sulfation occurs inside the battery. That's why it's much better to prevent sulfation from happening in the first place. What is the easiest way to prevent sulfation? Keep your battery charged.

That means driving your vehicle at least once a week at highway speeds for around 30 minutes or so. If you keep your car or truck in storage for part of the year, maintain its charge using a battery charger. Battery maintainers are a great way to do this since you can connect them to your battery indefinitely without fear of overcharging it. For other tips, read our article "How Do You Keep a Car Battery from Dying When Not in Use?"

Can Sulfation Happen with AGM Batteries?

All lead-acid batteries can suffer from sulfation during prolonged usage which is a normal part of an aging battery. That being said, certain types of lead-acid batteries are better than others.

AGM batteries are the most resilient of the bunch. Absorbed Glass Mat batteries will resist sulfation buildup for much longer than other lead-acid batteries and are a great choice for vehicles that tend to sit for long periods.

What is Battery Corrosion?

Corrosion is a buildup of colorful material, usually white, green, or blue, that appears on your battery's terminals or cables. This buildup can impede the flow of electricity and cause your battery to deteriorate over time. There are a few different reasons why corrosion happens. Sometimes, lead acid batteries release sulfuric acid vapor and hydrogen gas, which can react with the heat under your hood and the metal on the battery's terminals, leading to corrosion. Overcharging your battery can also cause corrosion, and as your battery ages, the terminals become more prone to it.

What Problems Can Corroded Battery Terminals Cause?

Corrosion limits the power that can travel from the battery to your vehicle's electrical and starting system and from the charging system back into the battery. This hurts your battery's performance, making it more difficult to start your engine.

It also impedes the battery's ability to charge properly and, if allowed to go on for too long, will kill your battery entirely. Corrosion can also damage other parts of your vehicle, such as the battery cables and other electrical system components.

How Do You Prevent Battery Corrosion?

Check your battery terminals for signs of corrosion regularly. If you notice a buildup of corrosion, you can clean it off using a battery terminal brush and a solution of baking soda and water.

You can help prevent future corrosion by spraying your terminals with an anti-corrosion spray. Batteries Plus also offers a set of terminal protectors coated in a compound that helps stop corrosion caused by battery acid fumes.

Finally, if you use a charger on your battery, be sure that the voltage of your charger matches that of your battery and that it's compatible with the chemistry of your battery (i.e. flooded lead acid or AGM). If your charger isn't equipped with a float stage, monitor the charging process to ensure you don't overcharge your battery.

Shop Batteries Plus for Your Auto Battery Needs

Are you experiencing issues with the battery in your car or truck? Bring it to your nearest Batteries Plus location and we'll test it for you, free of charge. If you need a replacement, we have top-quality auto batteries from trusted brands like Duracell Ultra, X2Power and more.

Plus, we offer installation on most makes and models at most locations. You'll find other essential gear like windshield wiper blades, jumper cables and flashlights in our Auto Center.

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