How To Remove Corroded Batteries From A Flashlight, Methods And Reasons

Jun 10, 2021   Pageview:40

Being reliable, the main purpose of a flashlight is to provide light in the darkness. By giving you portable illumination, outdoor LED flashlights become more and more useful in our life. Flashlights are also preferred by house owners for preventing emergency situations. They are now manufactured in distinctive designs and operations and there are many new features found in modern flashlights, like zoomable, mini, rechargeable and waterproof etc.

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The torch flashlights contain many components including case, contacts, switch, reflector, lamp, lens and the most important part, batteries. When the switch of a flashlight is pushed into the ON position, it immediately makes contact between two contact strips that begins a flow of electricity which is powered from the battery.

The batteries are connected in such a way that electricity (flow of electrons) runs right between the positive and negative electrode plates of the battery. The batteries rest atop a small spring which is further connected to a thin contact strip.

The contact strip goes down the length of the battery case and makes contact with one side of the switch. There is another flat contact strip on the other side of the switch? which runs to the lamp (light bulb) by providing an electrical connection. There is another part that is connected to the bulb that makes contact with the positive electrode of the battery which is at the top.

It completes the circuit to the lamp and the generation of electricity. When the flashlight switch is pushed into the OFF position, the two contact strips are moved apart and the path for the electrical current breaks, thus stopping the production of light and turning your flashlight off. 

The batteries of flashlights are usually alkaline and can also corrode. This corrosion reduces the efficiency of the battery and affects the performance of your Flashlight greatly. As alkaline batteries become old, the chemistry of the battery changes simultaneously. A byproduct of this chemical change is hydrogen gas. The excess of this gas can cause a pressure inside the battery which can eventually break the battery seal and potassium hydroxide will leak out. The leakage of potassium hydroxide can cause damage to other internal parts of the flashlight and as a result it will not function properly.

Corroded batteries can be a big problem. Limited access to the battery of a flashlight makes the task of removing a corroded battery more difficult. Not only corrosion from the batteries make a mess inside the flashlight, but the batteries may swell that causes them to become stuck. But by using vinegar or lemon juice and baking soda, you may neutralize the corrosion and safely remove the batteries.

One of the most common reasons for a battery terminal issue is corrosion. Corrosion can drain a lot of power out of a battery and reduces its lifespan. You can prevent your battery from corrosion by applying petroleum jelly on negative and positive posts of the cables. If the battery is corroded then the flashlight may have trouble starting. The corroded batteries can cause many serious problems? like melting, getting stuck and swelling etc so it is very important to remove these corroded batteries from your flashlight.

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How do you get a corroded battery out of a flashlight?

The symptoms for a corroded flashlight battery are: A slow starting ability, the components inside your battery will wear out and become less effective or useless, dim lights and electrical issues, a bad smell,corroded connectors, a misshapen battery case and an old battery. If you want to remove the corroded batteries from a flashlight then it can be easily done with the help of a mixture of vinegar and baking soda. This mixture will neutralize the corrosion and help the corroded battery to bring out easily. After that, cover the open end of the battery holder with a thin tin foil. Check if the batteries have come out. If not, then tap slightly on the body of the flashlight to make the batteries come out but use gloves while doing this to make sure that you do not get in touch with the battery acid otherwise it will harm your skin.

How do you get swollen batteries out of a flashlight?

When the battery of a flashlight corrodes, it swells and becomes stuck in the flashlight. To remove safely and easily swollen batteries from your flashlight you should wear gloves and eye protection. If it is a normal type battery, drill a small pilot hole in the battery and then use an old corkscrew or coarse lag screw threaded into the battery approximately 1/2 way or a little more. If it is badly stuck and corroded you may have to heat the flashlight casing up with a hair dryer or a heat gun to assist in removal of batteries. Grasp the cork screw or a simple screw and pull the battery out. Repeat the whole process for the second battery if needed. This is a very convenient method regarding the removal of swollen batteries. If your flashlight has a removable bottom then just take it off. You should then be able to simply get a screwdriver in and help push the batteries out.

What dissolves battery corrosion?

All batteries corrode over time. Especially if you are dealing with alkaline batteries that are mainly used in flashlights, the leakage normally manifests close to the contacts as a white and flaky substance. To dissolve battery corrosion, you should first make yourself and your workplace safe in order to avoid any inconvenience. This process is done by using water and baking soda solution. The baking soda has neutralizing power that dissolves the battery corrosion. Battery corrosion is normally dissolved to hinder the chances of corrosion on the battery of your flashlight in future.


Battery corrosion has become a very common problem regarding batteries nowadays. It can melt the battery of your flashlight and can cause many problems for you. For cleaning and removing corrosion from your alkaline batteries of flashlights you should not use any kind of toxic chemicals otherwise explosive reactions can occur so It is wise to clean a battery leak (occurred by corrosion on the battery system) with a mild household acid? like vinegar or lemon juice. Both the liquids work to neutralize the alkaline discharge rapidly. Batteries are highly sensitive to heat so you should keep your flashlights at or below the room temperature.


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