Expired batteries may not function properly, leading to device malfunctions. Additionally, there is a risk of leakage which can damage your devices or cause harm. It’s advisable to dispose of expired batteries safely and replace them with new ones for optimal performance.

While some expired batteries may still work, the reliability is unpredictable. Using them can also lead to safety hazards, such as overheating or swelling. To ensure your devices and personal safety, it's best to err on the side of caution and replace expired batteries.