How to Clean Battery Terminals (The Right Way)

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Get rid of chalky corrosion safely and quickly
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Whether you’re dealing with the battery in your car or an ordinary household battery, batteries can develop corrosion. Grime, damage, and old age can cause acid to leak from your battery, which creates that chalky material on the terminals. To help, we met with automotive repair specialist Duston Maynes to get expert guidance on how to get rid of this corrosion safely and efficiently.

How to Clean Car Battery Posts

  1. With a cold car, remove the battery terminals (do the negative terminal first).
  2. Mix warm water and baking soda together to make a thick paste.
  3. Apply the paste to your battery terminals.
  4. Scrub the terminals with an old toothbrush.
  5. Wipe the terminals dry before reattaching the battery.
Section 1 of 4:

Removing Corrosion from a Car Battery Terminal

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  1. You do not need to remove the battery from the vehicle to assess it or clean it. Pop the car hood open and locate the battery. It’s typically on the front of the engine block on the driver’s side. Visually inspect the general condition of your car battery. If the battery is not cracked or leaking battery acid, you can go ahead and start cleaning. [1]
    • If your battery case has cracks, it’s swelling, or it’s actively leaking, replace the entire battery.
  2. With a totally cold car, use your fingers to pry up the red and black plastic covers that protect the terminals. Examine the battery cables and clamps for excess wear or corrosion. Corrosion appears as a white, ashy deposit around one or both battery posts. If the cables and clamps are slightly corroded or have just a little buildup, follow the instructions below on how to clean them. [2]
    • If the damage is extensive (i.e. every inch of the terminal is covered in soot), you may want to completely replace the cables and clamps to avoid future problems.
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  3. Before cleaning the battery, disconnect the battery. To do this, loosen the nuts on the clamps using a wrench. Once loose, remove the negative clamp (marked with a “-”) first. Only after the negative clamp is removed, remove the positive clamp (marked with a “+”). [3]
    • The clamps may prove difficult to remove, especially if there is a lot of corrosion. You may need to use pliers to remove them.
      • Don’t worry about damaging the clamps with a wrench. If you need to use so much force that the clamps end up damaged, you need to replace them anyway.
    • If you do need to use pliers, be careful not to touch the tool to the car frame (or anything else metal) and the battery while working. This could potentially short out the battery.
    • Use a memory saver device to save your settings. Most modern vehicles will automatically save your radio, seat, and car settings when you disconnect your battery, but some models won’t. If you want to 100% ensure you don’t lose anything, use a memory saver device .
  4. Maynes explains that baking soda and water are the ideal combo for cleaning battery corrosion. Combine 2–3 tablespoons (30–44 mL) of baking soda with 1 tablespoon (15 mL) of distilled water in a small bowl. Stir the ingredients together with a spoon to make a thick paste. Keep stirring until all of the bits of baking soda are fully dissolved in the water.
    • If you prefer, you can also use a commercial battery cleaner instead of making your own with baking soda and water. Just follow the instructions on the label to apply it to the battery terminals.
    • Put on safety glasses and rubber gloves. You’re extremely unlikely to get any battery acid on your skin, but it is a serious skin irritant, so take some precautions. Maynes says you’re best off wearing some protective eyewear and rubber gloves to protect yourself while you work.
  5. Maynes explains that you just have to dip an old toothbrush or a lightly damp rag into the baking soda paste. Rub the paste onto the corroded or dirty parts of your car’s battery. Once the baking soda is applied, you will see it bubble and foam as it reacts with the corrosion. Give the baking soda mix at least 5–10 minutes to soak in and loosen the corrosion.
    • Be careful while you’re applying the paste. Although baking soda is generally safe, you should take care not to get it on other car components.
    • Warning: Maynes says, “Don't pour water directly onto the battery.” If you do, you could risk shorting the battery.
  6. 6
    Scrape off corrosion deposits with the toothbrush. Continue scrubbing the terminals with your baking soda paste and toothbrush. Add more paste whenever the old paste wears away and keep scrubbing until the corrosion is totally gone.
    • There are special battery terminal brushes if you feel like you need something stronger and stiffer than a toothbrush. If the corrosion is that extensive though, you probably need to replace the battery.
  7. Spritz a clean cloth with distilled water and wipe away the paste. Keep refreshing your rag with new water as you feel it drying out and continue wiping until almost all of the baking soda is gone.
    • Be careful not to rinse the baking soda paste into the battery vents, as the baking soda can neutralize the battery’s acid and shorten the battery’s life.
    • The vents are located on the sides of the battery and are connected to long vent tubes that direct harmful gases away from the vehicle’s cabin.
  8. Maynes explains that it’s essential you dry the battery entirely before reconnecting it to your vehicle. Make sure that the terminals are completely dry by rubbing the dry rag over them 2-3 times. Be sure to use a rag that doesn’t have any grease or oil on it!
    • Don’t use paper towels for this step. The paper will shred, leaving you with bits of paper towel stuck to your battery terminals.
  9. Dip 2 fingers into a jar of petroleum jelly and smear a thin layer across both the positive and negative terminals. Make sure your vinyl gloves are still on while you do this. Applying petroleum jelly to the now cleaned terminals will prevent corrosion from occurring again in the future. [4]
  10. To complete the cleaning, you need to reattach the clamps that you removed earlier to secure the battery in place and restore the electrical connection. Reattach the positive clamp to the battery first by tightening it with a wrench. Once it’s firmly in place, then you can attach the negative clamp to the negative terminal on the battery. Use a wrench to tighten that clamp in place as well. [5]
    • Once the clamps are on, replace the rubber or plastic shields covering the clamp/terminal junction.
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Section 2 of 4:

Cleaning a Household Battery Terminal

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  1. Open the device’s cover to access the battery cradle. Remove the battery cover to inspect the degree of corrosion. Assess these old batteries for cracks and leakage. Mild corrosion will appear as black spots, more severe corrosion appears as a white, ashy deposit around one or both battery posts or terminals. [6]
    • If you find a battery that’s leaking acid (and not merely corroded), throw it away immediately. Any leakage is likely potassium hydroxide, a strong base. Be sure to wear skin and eye protection when cleaning out the battery cradle, as potassium hydroxide is caustic.
    • If a device is powered by more than 1 battery, it’s possible for 1 battery to be corroded and another to be in fine shape. Pull out any non-corroded batteries and set them aside. You’ll reinsert them later once you’ve cleaned off corroded batteries and the cradle.
    • The following baking soda cleaning method is just for any corrosion around the terminals, not for a leaking battery.
  2. Maynes says that baking soda and water is the ideal option for cleaning any kind of battery terminal. Make your cleaning agent by combining 2–3 tablespoons (30–44 mL) of baking soda with 1 tablespoon (15 mL) of water. Stir the components with a spoon to make a thick paste.
    • Take care not to get baking soda on other electronic components—e.g., whatever electrical device the batteries that you are cleaning were housed in.
  3. Dip a cotton swab into the baking soda mixture. Smear the baking soda paste onto the battery connections and the 2 terminals at the end of each battery using the cotton swab. Once the baking soda is applied, you may see it bubble and foam, as it reacts with the corrosion. Let it soak in for about 5 minutes. [7]
    • Warning: Wear vinyl dishwashing gloves while cleaning any battery corrosion. Take care not to touch with bare skin the white crusty buildup, as it is caustic and could burn your skin.
    • Be careful not to get any water on your electronics when cleaning.
  4. When the foaming stops and there are no major deposits left to be scraped out, you’re ready to rinse off the inside of the cradle. Dip 1 clean cotton swab into a cup of distilled water . Then dab the cotton swab back and forth along the inside of the battery cradle. This will clear out any lingering baking soda and clean the connections so they’re ready to receive electrical current. [8]
    • Be careful not to get any water on any electrical components, or you could damage the electrical equipment.
    • Wait 15–20 minutes for the battery and cradle to dry out.
  5. Put the cleaned batteries into the now clean battery cradle. If you set aside un-corroded batteries earlier, fetch them and put them inside the battery cradle as well. Then, close up the case or put the cover back on. Put some pressure on the plastic cover to make sure that it’s firmly in place. [9]
    • You’re now ready to resume using your electronics!
    • If your battery develops corrosion again, replace it.
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Section 3 of 4:

Causes of Corrosion

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  1. 1
    Gas escape There are small vents on the side of every car battery that allow excess pressure buildup and gas fumes to escape. If a lot of those fumes end up escaping, the acid can cause corrosion on the terminals. [10]
    • You shouldn’t normally have any natural gas escape. If this is happening frequently, it’s a sign that something is seriously wrong with your battery.
  2. 2
    Overcharging If you have a rechargeable battery and you overdo it or you charged your battery recently after it died and let it charge for too long, overcharging can cause corrosion. [11]
    • Charging a battery causes the acid inside the battery to activate, which can cause fumes to build up in the battery if you let it charge too long.
  3. 3
    Damage Physical damage to a battery can cause corrosion. As the acid leaks out of the damaged battery case, it causes the chalky buildup you see. [12]
    • Do not use a damaged battery. Car batteries can explode if they’re not stable, and a damaged battery is a serious risk—especially if the battery is beginning to swell.
  4. 4
    Age Batteries naturally develop corrosion when they’re nearing the natural end of their life. Car batteries aren’t meant to last forever, so the corrosion could just be a sign that it’s time to get a new battery. [13]
    • Replace your battery every 3-5 years. Even if there isn’t any evidence of a leak, it’s important to replace your battery before a problem develops.
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Section 4 of 4:

Preventing Corrosion

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  1. 1
    Inspect your battery regularly. Batteries will corrode over time as the gases they release interact with the surrounding environment. By checking your batteries periodically, you’ll spot corrosion before it really gets out of hand.
    • Remember, even a little bit of corrosion is a sign you’re nearing the point where you need to replace the batteries, so the earlier you spot problems, the more time you’ll have to deal with the issue.
  2. 2
    Keep your batteries safe and dry. Exposing your batteries to moisture, extreme temperatures, or physical damage may create a leak that produces corrosion. The safer you can keep your batteries when you’re not using them, the longer they’ll last and the less likely they’ll be to develop corrosion. [14]
    • Always keep batteries indoors! Do not store batteries of any kind in an outdoor setting.
  3. 3
    Avoid overcharging your battery. If you have a rechargeable battery, avoid leaving it on the charger unnecessarily for extended periods of time. Overcharging not only reduces the overall lifespan of the battery, but it increases the odds the fumes from the interior of the battery expand far enough to leak out of the battery, which will cause corrosion. [15]
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  • Question
    How do I check a battery for earthing?
    Community Answer
    It's not really customary for a battery. But, I'd say if the battery is buried or is upside down and its posts are in the ground, either of these would be earthed and wasting their power.
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  • Question
    Can I get shocked if I touch a battery terminal?
    ConnorFisher
    Community Answer
    It's possible, but in most cases, touching the battery terminal won't shock you. Even if it does shock you, the battery won't seriously hurt you, since it only carries 12 volts. But, it's important to wear vinyl gloves so there's no chance of injury. And remove metal rings, watchbands, etc. Earthing while wearing a metal ring can burn through to the bone.
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      Tips

      • In some cases, the entire cradle of a household AA, AAA, C, D, or 9 volt battery may be removable from an electronic device. If this is the case, soak the entire case in water or a diluted baking soda solution to remove corrosion. However, in most cases you will have to patiently rub off the corrosion with a cotton swab, while the battery cradle remains in the device.
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      • If you decide to use gloves for this project, make sure to select gloves that resist chemicals (e.g., vinyl gloves). If you don’t use gloves and your skin comes into contact with corrosive chemicals, rinse your hands under running water immediately.
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      Warnings

      • Be careful when using water around electronic components. If you feel you cannot clean the battery terminals while keeping your electronics dry, don’t attempt to clean them. Instead, bring your device in for professional repair.
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      • Batteries contain strong acids or bases, both of which can burn your eyes and skin. Never try to open a battery. Any corrosion around the battery terminals should be considered caustic, since it can burn you. Use gloves and eye protection to keep yourself from being burned by a corroded, caustic battery.
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      • Car batteries should be considered dangerous. Car batteries release hydrogen gas when charging or discharging, which means they can be explosive. Keep open flames away and avoid any sparking while working around a car battery.
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      References

      1. ↑ https://www.lesschwab.com/article/batteries/how-to-disconnect-car-battery.html
      2. ↑ https://www.lesschwab.com/article/batteries/how-to-disconnect-car-battery.html
      3. ↑ https://www.lesschwab.com/article/batteries/how-to-disconnect-car-battery.html
      4. ↑ https://www.msn.com/en-us/lifestyle/cleaning-and-organizing/can-you-use-vaseline-on-your-car-battery-terminals-and-why-you-may-want-to/ar-AA1EXqQV
      5. ↑ https://youtu.be/kSkbTmtBZUc?t=161
      6. ↑ https://www.digitaltrends.com/cool-tech/how-to-clean-up-battery-acid/
      7. ↑ https://youtu.be/AV3yQByNjsI?t=125
      8. ↑ https://www.bobvila.com/articles/how-to-clean-battery-corrosion/
      9. ↑ https://youtu.be/AV3yQByNjsI?t=208
      1. ↑ https://exchange.aaa.com/wp-content/uploads/2012/09/AAA-Car-Care-Battery.pdf
      2. ↑ https://www.midtronics.com/blog/effects-overcharging-battery/
      3. ↑ https://www.aaa.com/autorepair/articles/know-when-to-replace-the-car-battery-8-key-warning-signs
      4. ↑ https://www.aaa.com/autorepair/articles/know-when-to-replace-the-car-battery-8-key-warning-signs
      5. ↑ https://www.aaa.com/autorepair/articles/know-when-to-replace-the-car-battery-8-key-warning-signs
      6. ↑ https://www.midtronics.com/blog/effects-overcharging-battery/

      About This Article

      Article Summary X

      To clean your battery’s terminals, first pop the plastic caps off of the positive and negative terminals by hand. Unscrew the negative cable by turning the nut on top of the cable counterclockwise with a socket wrench. Then, repeat this process on the positive cable and pull both cables away from the battery. To make the cleaning solution, throw on some nitrile gloves and mix 1 tablespoon (15 g) of baking soda with 1 cup (240 mL) of water to make a paste. Dip a rag into the paste and rub it over each of the terminals. Wait 5-10 minutes to let the paste foam and loosen up the corrosion. Next, grab a toothbrush and scrub the paste into the terminals. Use firm back-and-forth strokes to brush away the corrosion. Continue scrubbing until the corrosion is entirely gone. Wipe the paste off with a clean, damp towel. Then, rub a coin-sized drop of petroleum jelly into each of the terminals to lubricate them and prevent corrosion in the future. To finish, reattach the positive cable first before reconnecting the negative cable, and place the caps back on the battery. To learn how to prevent corrosion on your car's battery terminals using petroleum jelly, scroll down!

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      Reader Success Stories

      • Stanislaw L.

        Jun 1, 2023

        "Worked great for me. There was mysterious blue stuff on the battery terminal, removed easily with baking soda ..." more
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