If a battery leaked inside your favorite electrical or electronic gadget, don’t fret. You don’t have to throw it out. And you can fix it for a couple of dollars, at most. Here’s how to clean off battery acid.
Why batteries leak
Alkaline batteries and Ni-Cad batteries are prone to leak after they die. Some of the chemicals in the battery get consumed as you use it, but not all of them do. What leaks tends to be the left-over chemicals after you’ve used all of the chemical energy stored in the battery. Batteries rarely leak while they still have a charge.
But if you put a gadget or child’s toy away and forget about it, eventually the battery dies and leaks. So-called battery acid spills are usually potassium hydroxide, which is actually a base, not an acid. But it’s corrosive, and when it’s covering up the battery terminals it’s an insulator. These two things will keep the device from working again. Until you remove the leaky batteries and clean off the leakage and corrosion, that is.
How to clean off battery acid, er, corrosion
The prognosis for fixing damage from leaky batteries is actually pretty good, especially if the leak is confined to the battery compartment.
To clean off the leakage, you need an old toothbrush, cotton swabs, white vinegar or lemon juice, baking soda and water, isopropyl alcohol, and ideally, protective gloves and eye protection.
First, put on the gloves and eye protection. Remove the batteries and discard them. Next, scrub away any dried leakage with the toothbrush. The more you scrub away, the less you have to neutralize. You can use the toothbrush dipped in vinegar, or just use it dry. I’ve seen people use either way successfully. My general rule is that if the leakage appears wet, to use the vinegar. If it looks like it’s dry, start with a dry toothbrush.
Dip a cotton swab in the white vinegar or lemon juice and swab any remaining discoloration you see. You’ll hear it hiss and see it bubble. I prefer vinegar but lemon juice will work if it’s what you have. When you get all of the discoloration, switch to baking soda and water to neutralize any of the vinegar or lemon juice left behind. Be sure to check all sides of the battery terminals.
Clean up everything that remains with alcohol and a cotton swab. Let it dry thoroughly. About 30 minutes should be enough. Dry it off with a paper towel if you want to accelerate the process. Then replace the batteries and your device should work again.
And that’s how to clean off battery acid and other gunk from your battery compartment.
Cleaning up circuit boards
It’s not a bad idea to take the device apart and make sure none of the battery leakage got onto the circuit board. Corrosion on the circuit board can eventually damage it to the point where it will stop working. If you find any battery-related residue on the circuit board, clean it up with cotton swabs with white vinegar, then follow up with isopropyl alcohol, and clean it the way you’d normally clean a circuit board.
Battery damage is fairly common on old computers, and if you don’t stop the corrosion, eventually it can break an electrical connection and cause it to malfunction. This generally takes years, however. If the batteries leaked in your television’s remote control, chances are the remote control isn’t old enough to have sustained mortal circuit board damage.
If you’re cleaning up an old computer and you find damage that’s beyond what you know how to fix, it’s probably best to neutralize the corrosion, then have another hobbyist with more experience repair the board for you. A good technician can replace any damaged chips or sockets, and even repair damaged pads or traces. If you end up damaging the board trying to desolder components, they can fix that, but it’s cheaper to let them replace the part if you’ve never desoldered and replaced components before. It’s best to learn board work on something you don’t care about before you tackle board work on a prized vintage computer.
David Farquhar is a computer security professional, entrepreneur, and author. He started his career as a part-time computer technician in 1994, worked his way up to system administrator by 1997, and has specialized in vulnerability management since 2013. He invests in real estate on the side and his hobbies include O gauge trains, baseball cards, and retro computers and video games. A University of Missouri graduate, he holds CISSP and Security+ certifications. He lives in St. Louis with his family.