Why Do Alkaline Batteries Leak?

Alkaline batteries leak primarily because of the continuous discharge process that occurs even when they are not in use, leading to a build-up of gases internally. This internal pressure forces the corrosive electrolyte, potassium hydroxide, out through the battery's vents.

The Core Reason Behind Alkaline Battery Leaks

Even when not actively powering a device, alkaline batteries undergo a slow, continuous chemical reaction known as self-discharge. This process consumes the chemical components inside the battery. As the battery discharges, whether through self-discharge or powering a device beyond its useful life, several factors contribute to leakage:

• Gas Build-up: During the discharge process, hydrogen gas can form inside the sealed battery casing. As referenced, "the build-up of gases inside the battery can seep out through the battery's vents and cause them to leak potassium hydroxide, more commonly known as battery acid."
• Pressure Exertion: This accumulated gas creates significant internal pressure. To prevent the battery from rupturing, manufacturers design batteries with a small vent or seal that acts as a pressure relief mechanism.
• Electrolyte Expulsion: When the internal pressure exceeds the vent's tolerance, the gas, along with the corrosive alkaline electrolyte (potassium hydroxide), is forced out through these vents or compromised seals, resulting in the visible leak.

What is Leaking? Potassium Hydroxide

The substance that leaks from alkaline batteries is potassium hydroxide (KOH), which is commonly referred to as battery acid, though it is technically an alkaline substance (a base), not an acid. This electrolyte is highly corrosive and can cause damage to electronic devices, skin irritation, and other materials it comes into contact with.

Common Causes of Alkaline Battery Leaks

While self-discharge is the fundamental mechanism, several scenarios accelerate or trigger the leakage process:

1. Over-Discharge: Leaving batteries in devices that are turned off for extended periods, or allowing a device to drain the battery completely, can cause over-discharge. This state increases the likelihood of gas generation.
2. Mixing Old and New Batteries: Different ages or brands of batteries have varying internal resistance and discharge rates. When mixed, the stronger batteries will attempt to charge the weaker ones, leading to over-discharge of the weaker cells and eventual leakage.
3. Extreme Temperatures: Storing batteries in very hot or very cold environments can accelerate the chemical reactions inside, leading to faster gas build-up and pressure, increasing the risk of leaks.
4. Long-Term Storage: Even new, unused batteries can leak if stored for excessively long periods, as self-discharge is an ongoing process.
5. Damage or Defects: Physical damage to the battery casing or manufacturing defects can compromise the seal, making it easier for the electrolyte to escape.

Preventing Battery Leaks

Taking simple preventative measures can significantly extend the life of your devices and prevent corrosive damage:

• Remove Batteries from Unused Devices: If a device will not be used for an extended period, remove its batteries.
• Store in a Cool, Dry Place: Keep batteries at room temperature, away from direct sunlight, heat sources, and humidity. Avoid storing them in refrigerators or freezers.
• Replace All Batteries at Once: When changing batteries in a device that uses multiple cells, replace all of them simultaneously with new batteries of the same brand and type.
• Avoid Mixing Batteries: Never mix old and new batteries, or different brands and types of batteries in the same device.
• Check Batteries Periodically: For devices that are stored with batteries, check them every few months for any signs of leakage or corrosion.
• Purchase Reputable Brands: Stick to well-known, high-quality battery brands that adhere to strict manufacturing standards.

What to Do if an Alkaline Battery Leaks

If you encounter a leaking battery, follow these safety steps carefully:

• Wear Protective Gear: Put on gloves (nitrile or rubber) and eye protection before handling a leaking battery or affected device.
• Ventilate the Area: Work in a well-ventilated space to avoid inhaling fumes.
• Clean Up the Leak:
  • Carefully remove the leaking battery.
  • Use a cotton swab or an old toothbrush dipped in a small amount of vinegar or lemon juice (mild acids that neutralize the alkaline potassium hydroxide) to clean the affected contacts and battery compartment.
  • Wipe the area thoroughly with a damp cloth, then dry completely.
• Dispose Properly: Leaking batteries should be disposed of according to local hazardous waste regulations. Do not throw them in regular household trash.

Common Causes and Prevention Summary