Why are they dangerous goods?
In a word? Fire.
Increasingly powerful, lithium batteries are designed to keep devices running for hours or days at a time. To achieve this, they contain high levels of electric energy. If packed incorrectly or damaged in transit, lithium batteries can short-circuit, causing them to overheat and catch fire.
Poor quality and counterfeit batteries are most at risk because they haven’t been through the
rigorous testing required.