If you’ve put away a device and forgotten to take out the batteries, the terminals are probably covered in battery acid by now. The good news is, you can clean them pretty easily, depending on the severity of the leak.
Alkaline batteries—the kind you use to power clocks, TV remotes, flashlights, children’s toys, and so on—are made of a cathode (manganese dioxide) and an anode (zinc). These react to one another and produce the electrons, which, with the help of an electrolyte (potassium hydroxide), power your gadgets.
When alkaline batteries completely discharge (which happens long after they stop providing adequate juice to your devices), the potassium hydroxide breaks down. This process produces hydrogen gas and builds up pressure inside the battery. Eventually, this ruptures the steel casing, and potassium hydroxide leaks out in the battery compartment and, sometimes, over the circuitry inside the device.
It can take years for this to happen or just a few months, depending on the quality of the battery and how much parasitic draw (the power a device uses while it’s turned off) the item has. This is why it’s always important to remove the batteries before you stow away gadgets.
Update, 1/26/22: Verified all content and links still good.
If you’ve come across an old, beloved gadget that’s now covered in this beautiful battery vomit, it doesn’t take much to clean it up. You probably already have everything you need around the house.
Before you begin, though, you might want to temper your expectations. Once battery acid starts to leak inside a device, it oxidizes and starts to corrode any components with which it comes in contact. If the leak isn’t too bad, the device might be salvageable. If the acid has leaked onto critical components and been there long enough, though, it might have caused permanent damage.
Warning: Keep in mind that potassium hydroxide is caustic, which means it can burn your skin and irritate your eyes and lungs. Luckily, it transforms into potassium carbonate once it absorbs carbon dioxide from the air. Unlike potassium hydroxide, it’s mostly harmless. Still, it’s a good idea to take precautions—wear gloves and safety glasses whenever you’re cleaning up a battery leak.
Aside from your safety equipment, you’ll need the following items to help you out:
- DeoxIt, vinegar, or lemon juice: If you don’t have a contact cleaner (like DeoxIt), vinegar or lemon juice both work just as well.
- Isopropyl alcohol: This isn’t absolutely required, but it’s handy to clean off the vinegar or lemon juice and leave the circuitry squeaky clean. At the pharmacy, you can get 91 percent, which is ideal, but 70 percent will work, too.
- Q-tips: These are small enough to fit into most battery compartments so you can clean the battery contacts and circuitry.
- A toothbrush: You won’t need this every time, but it comes in handy for larger acid spills that make their way to circuit boards or other areas of a device. A new toothbrush is best, but you can use an old one as long as you clean it first.
- Paper towels or rags: You want something on-hand to clean up any messes or to protect other areas of the device from cleaning agents.
- Tools: You might have to take the device apart to gain full access to the battery leak. The Pro Tech Toolkit has everything you need to disassemble 99 percent of the world’s gadgets.
For this article, we’re going to work on a fairly modern HP keyboard with leaky batteries that no longer works. Let’s see if we can get it cleaned up and working again!
All I need to take apart this battery-acid-soaked keyboard is a screwdriver. It takes a bit of prying to remove the rubber feet. Your device might be more complicated to take apart than a keyboard, though. Before you dive in, take some time to investigate the entry points.
The keyboard is held together with some plastic clips, which are easy to separate. We’re in!
This spill won’t take too much elbow grease to clean up, but your device might be in worse shape than mine.
Dip a Q-tip in your cleaning agent, vinegar, or lemon juice, and then soak the affected area with it. The battery “acid” in alkaline batteries (the electrolyte or potassium hydroxide) isn’t actually an acid—it’s just a base. Because vinegar and lemon juice are mild acids, they help neutralize the base and cut through a battery spill fairly easily.
On most gadgets with simple circuitry, the negative battery connector is usually held down by a screw or clip. You should be able to remove this easily and clean it separately. Place a towel underneath to catch any overspill.
After you soak and scrub the area a bit, use your towel to clean up the mess inside the device. You can also use your screwdriver to press the towel into crevices and soak up the cleaning agent and potassium carbonate.
Repeat this process until all evidence of the battery leak is gone. Then, use the same method with the isopropyl alcohol to scrub the area, leaving a fresh, shiny battery compartment.
Let everything dry thoroughly, and then reassemble your device. Make sure you properly dispose of the leaky batteries, and then insert some brand-new ones and fire up your gadget!