Optics Mag is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Read more.

How to Clean Battery Acid From a Flashlight in 3 Steps

Last Updated on

Flashlight Battery

If you’ve had a battery for a long time, you know just how annoying corroded batteries can be. Although you may be tempted to throw the entire flashlight out, there are ways that you can safely clean the battery acid from the flashlight.

In this article, you will learn how to clean battery acid from a flashlight in a safe and efficient manner. Let’s dive right in.

shutter camera divider

A Note on Safety

Before we get started, let’s take a minute to talk about safety. You always want to put your safety first when dealing with toxic materials such as battery acid. Even though the battery acid isn’t actual acid (it’s alkaline potassium hydroxide) it is still dangerous to the touch. It can cause serious chemical burns that you want to avoid.

So, get started by getting all the safety gear you need. You will want to wear chemical-resistant gloves and safety goggles. Make sure to lay down a disposable plastic tablecloth or multiple layers of newspaper over the surface you intend to be working over as well.

Make sure to stay away from any children or pets, too. As much as we love these additions to the family, they can be a distraction, and the last thing we want is to be distracted when dealing with toxic materials. 

What You’ll Need

  • Chemical-resistant gloves
  • Goggles
  • Protective clothing
  • Disposable plastic cover
  • Towels
  • Bottlebrush or toothbrush
  • Wire brush (optional)
  • White vinegar
  • Small dowel rod
  • Needle nose pliers
  • Water
  • Hard surface

shutter camera divider 2

How to Clean Battery Acid From a Flashlight in 3 Steps

Once you have your safety gear on, have removed all distractions, and gathered all your supplies, it’s time to clean the battery acid from your flashlight. Here are the steps you will need to take:

1. Remove the Battery

Firstly, remove the battery. In some cases, the old batteries will slide right out. Other times, the batteries will be swollen and fused with the inside of the flashlight. In that case, it will take extra work to remove the batteries.

If you are having trouble removing the batteries, you can use a small dowel rod or needle-nose pliers to pull the batteries out. In the case that the batteries are really stuck, pour white vinegar around the batteries, and let the vinegar sit for a few hours. Then, pull on the batteries until they fall out.

In the most extreme scenarios, even vinegar won’t help. If vinegar is not able to loosen the batteries, it’s best to just throw away the flashlight and get a new one. There will be no way to remove the batteries without damaging the flashlight.


2. Remove the Acid

Now that the batteries are removed, you can remove the acid. The acid will look like a white powder or a sort of rusty liquid residue on the inside of the flashlight. Begin by removing any excess by wiping out the inside with a rag. Try to wipe from both ends.

Once you’ve removed the excess, put in a few drops of white vinegar. The vinegar will create a fizzing sensation. That is completely normal. The fizzing occurs whenever the alkaline residue is neutralized.

After the fizzing stops, take a bottlebrush or old toothbrush to clean the inside of the flashlight. In more extreme cases, you can use a small wire brush instead.

After you’ve done all the scrubbing, simply rinse out the inside of the flashlight with some water. Let the flashlight completely dry once you have thoroughly scrubbed and disinfected the inside.


3. Dispose of the Batteries

While the flashlight is drying out, you will need to dispose of the batteries. In some locations, there will be very specific guidelines for how to dispose of batteries. Contact your local sanitation department to find out how to properly dispose of these potentially dangerous items.

shutter camera divider

Other Tips for Additional Help

If vinegar doesn’t help to remove the corroded batteries, there are some other materials that may work too. Coca-Cola and baking soda have been found to help with the removal of corroded batteries. These materials aren’t guaranteed to work, but they can help in some situations.

For future reference, you can avoid this hassle by trying to prevent batteries from leaking in the first place. One of the easiest ways to prevent this from happening is to use and store your batteries correctly. Make sure to insert the batteries as they ought to be. Whenever you are storing the flashlight for some time, remove the batteries first.

Are Ring Cameras Waterproof? Do They Get Wet?

shutter camera divider 2

Final Thoughts

Instead of tossing your flashlight in the garbage can the next time you see battery acid, you now know how to remove that acid. Using the technique above, you should be able to neutralize the material, remove the acid, and restore your flashlight to its previous state.

Keep in mind that not all flashlights are salvageable, though. If you are unable to remove the batteries with the methods mentioned above, it’s best to just toss out the flashlight and get a new one.

Read More: When Were Flashlights Invented? History of the Flashlight


Featured Image Credit: fotoblend, Pixabay

About the Author Robert Sparks

Robert’s obsession with all things optical started early in life, when his optician father would bring home prototypes for Robert to play with. Nowadays, Robert is dedicated to helping others find the right optics for their needs. His hobbies include astronomy, astrophysics, and model building. Originally from Newark, NJ, he resides in Santa Fe, New Mexico, where the nighttime skies are filled with glittering stars.

Robert Sparks Profile Picture