What is the primary danger associated with malfunctioning lead-acid batteries?

The primary danger associated with malfunctioning lead-acid batteries is the risk of explosion. This can occur due to the buildup of hydrogen gas, which is produced during the charging process. If a lead-acid battery is overcharged or damaged, it may generate excessive amounts of hydrogen gas, particularly when there is a poor ventilation situation or a spark occurs nearby. The combination of hydrogen gas and air can create an explosive environment, leading to a violent reaction if ignited.

Understanding this risk is vital, as it underscores the importance of proper battery maintenance and monitoring during use and charging. While other issues like overheating, acid leakage, and battery corrosion are certainly concerning and can pose risks, the potential for an explosion represents an immediate and significant safety hazard that warrants special attention when working with lead-acid batteries.