How Do I Keep My Battery From Corroding in My AA Flashlight: Guide + Tips

Battery corrosion is everyone’s problem. So, how do I keep my battery from corroding in my flashlight, you may ask? This article has the answer and more info.

Everyone must have encountered the problem of battery corrosion. Whether the battery is used in your flashlight or has been stored for years, most of them still corrode. So, how do I keep my battery from corroding in my best AA flashlight, you may ask?

While almost all batteries will corrode through time, there are a few batteries that promise not to leak. However, it’s good to understand why certain batteries corrode. Is it preventable? What are the ways to keep the batteries from corroding? Or, if the batteries corrode in the flashlight, is there a way to salvage the flashlight and will it still work? All these and more are discussed in this article.

Why Do Batteries Corrode?

Even though you don’t use the batteries, they will still corrode. Why is that?

Consumer alkaline batteries and even other types of batteries are made using almost the same technology and components. Batteries have two terminals — anode (negative) and cathode (positive). To be able to light your flashlights, there must be a complete connection from the anode to the cathode. Electrons flow from the anode to the cathode.

Commonly, there are two reasons why batteries corrode — self-discharged and parasitic drain. Batteries discharge even when not used after seven years. This is because negative charges from the anode will be attracted to the cathode. And, when the connection is complete whether by air or through a conducting material, it’ll slowly drain. When the battery becomes dead, it’ll out-gas and eventually corrode.

Parasitic drain, on the other hand, could be because of faulty relay or switch and so on. So, even though you don’t use the flashlight, it will keep the batteries to slowly discharge. When the battery becomes dead, it will leak and may cause corrosion.

Whether the battery ages or used up, there are still chemical processes inside it. And, one byproduct of this is hydrogen gas. The excessive amount of this gas inside will cause pressure build-up. The reason why corrosion starts near the terminal is that the cap of the anode and cathode may always have leaks.

As the pressure inside builds up, it may rupture the seal and leaks out in the form of potassium hydroxide. It’ll react with carbon dioxide in the air to form potassium carbonate — the white powder you’ll see surrounding your battery or in the battery chamber of your flashlight. If you are still confused about how the corrosion happens, this YouTube video will be very helpful to you.

Tips on How to Prevent Corrosion

You’ve read above that there are reasons why batteries corrode and this is inevitable. Especially if you’re using alkaline batteries on your devices, chances are if you’ll leave dead batteries inside them, it’ll corrode through time. Yet, you don’t need to worry as there are manufacturers that offer leak-free batteries. Energizer, for example, has batteries that they advertised and guaranteed 100% no leak.

For those who don’t want to buy such batteries, there are a few steps that you can do to prevent the corrosion of the batteries in your flashlight.

Don’t Store Your Flashlights in High-Temperature Places

Drastic changes in the temperature can affect the chemical reaction inside the cell, which could shorten the shelf life of the batteries. Store the flashlights with alkaline batteries in a place with a temperature between 50 and 77°F.

Remove Batteries

As mentioned, most batteries do corrode, unless you’ll get “no leak” batteries. The corrosion may damage your flashlight, as well. So, if you don’t use your flashlight often, better remove the batteries and you may put them in a battery caddy.

Use One Brand at a Time

It’s advisable not to use different brands on your devices. If you’ll use batteries from different brands, they may have different discharge states. Reverse charging could happen, which will weaken the batteries — making them prone to leaking.

Don’t Use Dented Batteries

If you will purchase batteries, find those without any dent, some may already have rust. Damaged batteries or those with dents may have been exposed to pressure, which makes them prone to leaking. If you feel that the batteries are not new, don’t buy them, they may give in and, in the worst case, may damage your flashlight.

Get a Lithium-powered Flashlight

Lithium batteries have lesser chances of leaking and they have better cold-weather performance. If you can still make a choice, get a flashlight that can be powered by lithium batteries, as well.

What You’ll Do If the Batteries Have Already Corroded?

Once you have noticed the corrosion, you can still do something to prevent damage to your flashlight. However, you should know that potassium hydroxide can cause skin, eye and respiratory irritation, so only work on your flashlight with gloves.

You need cotton and distilled white vinegar (acidic vinegar) or lemon juice. Wet the cotton with vinegar or lemon juice and dab it on the white fluff. The reaction will take place automatically and liquid will start to disappear when it comes in contact with potassium carbonate. The white powder will soften, so, you can just brush it out or wipe it with a piece of clean cloth.

Once you have taken off the batteries and all the white fluff in your flashlight, carefully wipe it to ensure that there will be zero corrosion left. If your flashlight still works, the next time you’ll use it, have lithium batteries, instead.


While alkaline batteries are cheaper and more common, they are prone to leaking after some time. When these batteries are left inside your flashlight, they may corrode and could damage your tool. So, if you’ve ever asked yourself, “How do I keep my battery from corroding in my flashlight?” this article just gave you a few answers.

These are not only answers, but they are the best practices to keep your flashlight corrosion-free. Always remember, alkaline batteries will discharge and degrade. But, if you are just mindful of your things, you can remove the batteries when not in use. You can also use lithium batteries, but they are quite expensive. Finally, you can use ‘no leak’ batteries that guarantee a 100% corrosion-free battery and flashlight.

Leave a Reply

Your email address will not be published. Required fields are marked *