The dangers of overnight charging power banks, particularly for those with larger capacities, can be significantly increased when they are left charging past full capacity. This instability can lead to a phenomenon known as thermal runaway, which occurs when the battery's internal temperature rises. Other issues include physical damage, prolonged heat exposure, and incompatible cables. Notable incidents have occurred in the past, including a recent incident involving a Los Angeles reporter who had her portable charger explode in her bed.