How to Fix Corroded Battery Terminals

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Introduction: How to Fix Corroded Battery Terminals

About: I've always liked pulling things apart - it's the putting back together again that I have some issues with!

Many a time I’ve managed to get my hands on some electronic gizmo only to find that the battery compartment totally corroded. It’s usually one of the main reasons I think that people throw toys and whatever else takes batteries away.

The corrosion is caused by potassium hydroxide which can leak out of alkaline batteries (these are the usual types of batteries you put inside toys etc). All batteries discharge, either through use or just slowly through the production of hydrogen gas which forms pressure in the battery. Eventually that pressure will find a way out through a seal or as the battery ages, through corrosion or rust in the outer shell.

As soon as the first signs of a leak forms, then the best thing to do is to get rid of the battery. if you don’t get to it in time however, then the corrosion can grow and spread out of the battery which causes oxidisation and corrosion of the terminals making your device caput.

This Instructable will go through a couple of ways that you can fix your device to bring it back to life again. The first is the most extreme corrosion where the terminals have to be replaced, the second is a small amount of oxidisation which only needed the potassium hydroxide to be neutralised and the terminals to be cleaned.

You can take precautions though to stop this happening such as not mixing different battery types in the same device, replacing all of the batteries at the same time, storing in a dry place and at room temperature, and removing batteries for storage of devices. I’m inherently optimistic (and also lazy) so I’ve never taken any of these precautions but it’s definitely good practice, especially with expensive electronic goods.

Step 1: Parts and Tools

Your parts are going to be any electronic goods that need terminal cleaning and/or relacing. The following though will come in handy when you are going this type of work

Tools

1. Battery Holders. I have a bunch of these lying around which are good for projects. You can also use the terminals from them to repair other electronic goods.

2. You can also just buy these terminals from eBay

2. Small files

3. Vinegar

4. Small paint brush

5. Needle nose pliers

6. Ear cleaners

7. Wire cutters

8. Soldering iron

9. Rubber gloves – to protect your skin from the potassium hydroxide. I have touched it before and it does mildly irritate the skin so it’s best to use gloves when handling.

10. Eye protection – self explanatory

11. Protective mouth and nose mask. Potassium hydroxide can be quite dangerous and breathing it in can be toxic. Better to be safe then sorry.

Step 2: Removing Leaking Batteries

Don’t use your fingers to try and remove the batteries. The potassium hydroxide inside the battery can irritate your skin (I know as I’ve touched it before!). Potassium hydroxide is a caustic agent and is the chemical that corrodes the terminals and destroys the batteries. You may have also seen a feathery crystalline structure forming around the battery and terminal as well. This is potassium carbonate and forms when the potassium hydroxide reacts with carbon dioxide in the air.

For those who want to understand more about the chemical components inside an alkaline battery, please check out the following

Steps:

1. Place a set of rubber gloves on and some safety glasses

2. Use a small screwdriver to pull the batteries out. The glasses here are very important as it is easy to flick small pieces of the corrosion whist pulling out the batteries.

3. Sometimes that batteries can be so corroded that they virtually weld themselves to the terminals. In this case you will need to use a large screwdriver and maybe some pliers to remove them. You’ll probably rip out the terminals as well so be careful you don’t pull any wires out at the same time

4. Dispose of the batteries in a plastic bag.

Step 3: Removing the Corroded Terminals

Next thing to do is to remove all of the corroded terminals. It can be tricky sometimes to do this if they are severely corroded as bits can break off and the grooves in the battery holder can get clogged-up.

Steps:

1. Use a small, thin screwdriver and push this between the top of the terminal and the battery holder. This should bend out the terminal

2. With a pair of needle nosed pliers, grab hold of the terminal and pull it out.

3. If the terminal has solder points, make sure you de-solder or cut the wires and cut them away to be able to remove them easily

4. Dispose of the corroded terminals once removed

Step 4: Cleaning the Battery Cover

The battery holder that I fixed came away from the torch so make it easy to wash and clean. However, this might not always be the case as it will depend on what type of electronics you are cleaning.

Steps:

1. You can neutralise any leftover potassium hydroxide (a caustic agent which acts a little like acid) with some vinegar. Many comments have been made on this in the comments section and initially I also included baking soda as a way to neutralise the alkaline. I've removed this as there is a fair bit of contention if this would actually work or not.

2. Next if possible, wash out the bottom of the battery holder and clean any of the old potassium hydroxide away from the case. If you can’t remove the battery holder, then you are going to have to be a lot more careful when cleaning the area. Use a damp cloth instead of running water and remove any leftover potassium hydroxide residue

3. Next, you may need to remove any pieces of terminal or corrosion that is in-between the grooves that the terminals sit in. Use something thin and sharp to remove anything lodged inside the grooves.

4. Lastly, give the area a clean with some Isopropyl Cleaning Alcohol to remove any last traces of oils, stains etc.

Step 5: Sourcing Some Battery Terminals

In some cases, the corrosion is so bad that you need to replace the terminals inside the battery compartment. One of the easiest places to get these is from old battery holders. You could also grab the terminals out of any old electronic parts.

You can also buy the terminals from eBay and I have put a link in the parts section

Steps:

1 If your battery terminals have tabs on the back, make sure you lift these up first. You might also need to de-solder any wires on them if you got the terminals out of a toy etc.

2 Next, use a small screwdriver to push them out of the battery holder. Just place the tip of the screwdriver into the bottom of the terminal and lift it out of the battery holder. They are held in place by a couple of grooves in the side of the battery holder so should come out relatively easily.

Step 6: Modifying the Battery Terminals

Chances are you will need to modify the battery terminals so they will fit into the batter holder. You can do this pretty easily with some wire cutters and a dremel if you have one.

Steps:

1 First, try and fit one of the terminals into the battery holder grooves. If it does fit, then you can probably ignore this step and move onto the next. If not, then you will need to modify it.

2 Trim the sides of the terminal with some wire cutters and try to push into the grooves again in the battery holder

3 I also had to add a small slit into the terminal in order for them to fit which I did with a dremel.

4 Once you have modified, it’s then time to add them to the battery holder

Step 7: Putting the Battery Terminals in Place

Steps:

1. The first thing to do is to determine the orientation of the terminals. You need to make sure that the spring section on the terminal will be touching the negative part of the battery and the flat section is touching the positive.

2. Usually you can just look on the bottom of the battery holder and there will be images or the orientation. If not, then work out where the positive wire is going to be connected to the terminal and use this as a guide on the orientation of the terminals.

3. Place the terminals into the battery holder grooves and push into place. If they are a little loose then usually the batteries will hold them into place. However, you can slightly bend the terminal and push it back into the grooves which will make the fit a little tighter.

4. Once you have all of the terminals in place, solder the positive and negative wires to the solder points on the terminals

Step 8: Add Some Fresh Batteries and Test

Steps:

1. Before you screw everything back into place, add some batteries and make sure everything works as it should.

2. If everything works ok – replace the screws and covers and whatever else needs replacing to finish off your part

3. Lastly, give it another test and make sure it works

4. Now if you don’t want to have to do this all over again, go back to the intro and follow the precautions

This is really the most extreme case of having to fix battery terminals. The next sample, I think is more common and is more oxidisation of the terminals due to some leakage of the batteries. It’s easier too to fix!

Step 9: Fixing Oxidised and Minor Corroded Terminals

I found this cool, vintage mike at the dump and wanted to try and get it going again. Initially I tested it not knowing that it needed an AA battery and thought it was probably something to do with the wiring. After un-screwing the case however, I discovered that it needed a AA battery to run. The battery had been in place for some time and the terminals were oxidised and had some minor corrosion damage. I could have replaced the terminals but decided it would be easier just cleaning them

Steps:

1. Remove the old battery with a screwdriver and dispose of. Even though there was not as much damage and leakage as the first sample, I still made sure that I wore gloves and eye protection. They are considered safe to dispose of in the bin (imagine how many batteries get thrown away each day!) but there might be some local laws that require you to dispose of them in other ways

2. You can see in the images that there is a little corrosion and potassium hydroxide on the end of the terminal but that the terminal itself looks relatively unaffected structurally.

3. The brown streaks you can see running through the middle of the battery holder is actually glue that has discoloured over time, not corrosion

4. The next step is to neutralise the alkaline from the potassium hydroxide.

Step 10: Neutralise the Acid

Next thing to do is to neutralise any residual potassium hydroxide left of the terminals. There have been many comments left on how best to neutralise the corrosives from the potassium hydroxide. As potassium hydroxide is a strong base, then an acid like vinegar or lemon juice is probably the best thing to use when neutralising an alkaline like potassium hydroxide.

Here's a little more information on acids and bases for those who are interested and how to neutralising.

Steps:

1. First thing to do is to add the vinegar to a small container like a bottle cap lid.

2. Next, add a little to each terminal with a small paint brush or something similar.

3. Wipe off any excess from the terminals and leave to dry

4. Now that the potassium hydroxide has been neutralised, it’s time to clean-up the terminals

Step 11: Cleaning Up the Terminals

You need to remove any oxidisation and corrosion from the terminals. I find that the best thing to use is a small file but you could use sandpaper or an emery board or nail file as well.

Steps:

1. Use a small, fine file on the terminal until the oxidisation and any corrosion is removed. You may not be able to get it all off but sure you get as much as possible.

2. Once you have removed the oxidisation, give the terminals a clean with some isopropyl alcohol. You can also add some non-oxidising grease to help stop any further oxidisation.

3. You can sometimes remove the terminals from the grooves without having to undo any screws or removing any wires. It can make it easier to file if you can do this – just be careful that you don’t break any wires etc.

Step 12: Add a Fresh Battery and Test

Steps:

1. Once the terminals are clean and back into place, you can add a battery/s and test.

2. As before, it’s best to test before you screw everything back into place

That’s it! Hopefully you have managed to bring something back to life again with only a little bit of work.

Do you have any other tips? Let me know in the comments

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139 Discussions

0
lonesoulsurfer
lonesoulsurfer

2 years ago

Hi All,

Thanks for the comments. I have updated the section in the Instructable on what to use to neutralise the Potassium Hydroxide that can be produced in Alkaline batteries.

0
jude02075
jude02075

5 months ago on Introduction

Thank you so much for explaining how to remove and replace corroded battery terminals. I've looked all over the Internet, finally came across your instructions. Wonderful!! Thanks, now I just have to find something that will fit. Keep up the great work.

0
lonesoulsurfer
lonesoulsurfer

Reply 5 months ago

Awesome. Glad it was helpful

0
Advising Elf
Advising Elf

11 months ago

Baking soda is helpful, too. Not for neutralizing the potassium hydroxide (both are alkalines, or "bases"), but for dissolving the traces of corrosion products left after you scrub.
I use it when cleaning the corrosion products from car battery cable ends. Try it sometime. If you dip the cable end in vinegar, it just sits there. If you dip it in a baking soda solution, it fizzes like crazy. It's actually best to scrub the corrosion products off, soak it in baking soda solution until it stops fizzing, then soak it in vinegar because it will clean the metal surfaces of the secondary reaction products, then neutralize the vinegar with a dip in fresh baking soda solution. It's not good to leave any acid hanging around.
Good Instructable!

0
lonesoulsurfer
lonesoulsurfer

Reply 10 months ago

Another great tip. Thanks for your comment

1
allan.sheldon8
allan.sheldon8

11 months ago

You're a hero mate. Who knows how many people you've influenced to repair electrical items rather than throwing them away? ....well I'm one of them for a start!
An excellent instructable.

0
lonesoulsurfer
lonesoulsurfer

Reply 10 months ago

Thanks bud. Dunno if I’m a hero but I’m glad the ‘ible have come in handy.

0
pguncheon
pguncheon

11 months ago

I'm not sure if this has been mentioned here, but battery manufacturers generally warrant their batteries against leakage and will pay for or replace items damaged by leakage. I had leaking batteries destroy the sensor unit on my $300+ welding helmet. I contacted the company, and after filling out a few online forms, received a check for the full amount of the helmet. The environment here seems to cause all batteries to leak once they are discharge. I no longer store batteries in seldom used devices, but even so every once in a while I will find some tool I have not used in years with leaking batteries in place.

I now use Panasonic Eneloop rechargeable batteries. Great storage and recharge capacities... except for the black ones.

I found that the black Eneloops (900mah - high capacity) are terrible. Not sure why, but even though they are more expensive, every single one I have purchased has failed to recharge after less than 20 cycles. They're supposed to last for hundreds if not thousands of recharges.

0
lonesoulsurfer
lonesoulsurfer

Reply 10 months ago

I never knew that but it makes sense about battery manufacturers warranting their product. I’ll have to remember that next time I have batteries leak on me and I can’t fix the problem.

0
vincepav
vincepav

11 months ago on Step 12

Step zero: make a drawing of the battery box and the batteries to know how to get the terminals and springs in the right place.

0
lonesoulsurfer
lonesoulsurfer

Reply 10 months ago

Def a good idea. Or take a few photos of the terminals

0
laparsons
laparsons

11 months ago

if you don't have any vinegar on hand, in a rush use Vinegar base window cleaner for a quick battery or car battery cleanup, just don't take a breath when you spray the connector.

0
lonesoulsurfer
lonesoulsurfer

Reply 10 months ago

Awesome - thanks for the tip

0
yrralguthrie
yrralguthrie

11 months ago

Potassium hydroxide KOH is potash, it is used to make soap. A skin irritant, but not dangerous. The best way to clean those terminals is with a wire brush and water or water and baking soda. Baking soda is of course used in cooking and can also be used to brush and whiten teeth. Water will neutralize whatever KOH is left after brushing. Anything more caustic is uncalled for.

0
Wellingtonsaam
Wellingtonsaam

1 year ago

This is very helpful. I could have avoided wasting a lot of equipments... Not now. I'll never trash gadgets again. Thankx a lot

0
ve6cmm
ve6cmm

1 year ago

I can't remember who manufactured the TITANIUM E batteries, and where I can still get them. They were fantastic, providing much more power than regular AAs. I could get hundreds of photos with my camera with the Es and maybe 20 with regular alkaline batteries.

The company I worked for at the time had these in Satellite transponders that lasted 3 years before we would replace them. They still had a fair bit of capacity in them.

I think the company pulled them because they were so good. They weren't inexpensive, costing about $5 Canadian each, but they were well worth the price as they lasted much longer than conventional AAs.

0
RicksterInstructables
RicksterInstructables

Reply 1 year ago

Energizer “Ultimate Lithium” might be what you’re thinking of.
They come in AA and AAA sizes.
They are slightly higher voltage than alkaline cells, but not enough to be a problem in probably 99% of devices.
They are not rechargeable, but they have at least 50% (according to my testing) morecapacity than the best alkalines. They are also significantly lighter in weight.
They also work much better at low temperatures (below 0C) than alkalines.
And finally, they have better performance in high current devices - such as camera flashes, toys etc.

I have never seen one leak.

They are all around better, except they cost significantly more.

0
ve6cmm
ve6cmm

Reply 1 year ago

I have tried these but thay aren't as good as the Titainium E's. From what I understand, they are no longer available;

I do have to say that this instructable and it's comments have been very interesting. Lots of ideas and methods to consider. Thanks to all.

1
RicksterInstructables
RicksterInstructables

Tip 1 year ago

The absolute best thing you can do is to buy a small jar of Caig De-Oxit D100.
(https://www.amazon.com/CAIG-Laboratories-D100L-2DB-Electric-Cleaner/dp/B0002BBVN2). Buy the small bottle that comes with an applicator brush in the cap. It’s like a nail polish bottle.
It may seem expensive, but a little goes a long way and it will last you for many years. I discovered it many years ago. I only just recently had to purchase a new bottle.

It prevents corrosion of the terminals. It helps clean corroded ones.
You will never have to “shake” a flashlight again to get it to work.
If your batteries do leak, it’s much easier to clean up the mess.

Any/every time I install or replace batteries I always put some on the terminals and the ends of the batteries.

Oh, and don’t buy batteries at the dollar store. They are not worth the money you save.
Buy a name brand.

Finally, I’ve found that buying batteries online is sketchy at best. Sometimes they are at or past expiration. Some come loose packed (not in original card packages) - I think those may be rejects, or possibly used. I now only buy batteries from retail stores (Home Depot, COSTCO etc),

You can thank me later!

(Note on my comment regarding used batteries. Many companies replace batteries in their devices on a schedule, rather than waiting for them to die. This results in a box of used, but not quite dead yet batteries, which I suspect find themselves somehow on Amazon, EBay etc.).

0
Rich6006
Rich6006

2 years ago on Step 2

That's what happens when you use Duracell batteries. Great way to clean up the mess that they leave though.

Thanks for the helpful tip.