According to the Carmel Fire Department, that simple habit is contributing to a growing number of house fires involving lithium-ion batteries and charging equipment. Read More: Airline Sets New Lithium-ion Battery Limits for PassengersWhy Lithium-Ion Batteries Can Be DangerousLithium-ion batteries power many of the tools and devices we use every day, from cordless drills and lawn equipment to e-bikes and electric scooters. Charging these batteries isn't inherently dangerous, but firefighters say the problems can occur when:Batteries are left charging long after they're full. When a lithium-ion battery fails, it can generate intense heat and ignite nearby materials very quickly. Keep charging batteries away from anything that can burn.