While most batteries get used and disposed of before ever presenting a problem, very old or damaged batteries are prone to leaking. Heat and age can cause leaks as can internal pressures that build inside the battery as it drains. The chemicals inside batteries release hydrogen gas as they are used, which results in pressure on the battery seals. In some cases, the batteries may simply be defective.
No matter why they leak, batteries release potassium chloride when they do. Potassium hydroxide can cause chemical burns and other health problems if exposed to the skin, mouth, or eyes. Toxicity is also a concern if potassium hydroxide is ingested. It can also cause damage to any electronic device the battery was in when it leaked, which is why you should always remove the battery before storing any battery-operated devices.
Potassium hydroxide can cause mild to severe chemical burns if it contacts bare skin. Trace amounts of potassium hydroxide from battery leakage usually only result in minor itching and irritation. If you do come into contact with a leaking battery, flush your skin thoroughly with water. Eye exposure requires thorough irrigation and a visit to a physician. Respiratory problems may also occur in some people after exposure to this chemical. Promptly visit your doctor or an emergency room for airway support in the event of respiratory issues.
Potassium hydroxide from a leaking battery may cause poisoning if ingested or inhaled. Poisoning symptoms include severe abdominal pain, breathing difficulties, diarrhea, and a rapid drop in blood pressure, to name a few. If battery chemicals are ingested, call a physician or poison control center immediately and follow the given instructions. Do not induce vomiting unless instructed to do so by the physician. Instead, have the affected person drink milk or water.
A leaking battery is a damaged battery that should be promptly removed from electronic devices and properly disposed of. Batteries can be recycled through local programs or thrown away with your regular trash in every state except California, where they must be recycled. After disposing of leaking batteries, you may need to clean the device they were in. Although people often refer to battery "acid," potassium hydroxide is actually a base substance, not an acid. To remove the leaking fluid from a device's battery contacts, use an acid like lemon juice or vinegar and a cotton swab.
Proper handling and care is the best way to avoid the potential consequences of a battery leak. Reduce the risk of leaks by storing batteries at room temperature and never attempting to recharge batteries that are not clearly labeled as rechargeable. Never mix old and new batteries or two different battery brands. You should also never put your batteries in the refrigerator. According to Duracell, doing so does not actually extend the shelf life of the battery as some people believe.