Lithium-ion batteries represent one of the best inventions of the 20th century. They have one of the highest energy-density specifications of any battery made (energy density is the quantity of energy stored in a given space or volume). Small size and high power make these batteries suitable for many portable applications. Cordless power tools, lawn equipment, and eBikes all use them. Hybrid and electric vehicles have adopted the Li-ion as their main power source, too.
All this good news is offset by the fact that most Li-ion batteries are potentially small bombs. If they’re overloaded in some way or their temperature exceeded, they can catch fire or explode. For this reason, products incorporating lithium-ion, lithium-polymer, and lithium-phosphate batteries must have some measurement capability and protection capability.