Battery technical

The charging efficiency (coulombic efficiency) of lithium-ion batteries is hypothetically almost 100%. What does that mean?

Efficiency refers to the ratio between energy input and usable energy. A charging efficiency of nearly 100% means that the energy input is nearly equal to the ampere hours produced. Measured in watt-hours, the energy efficiency of a lithium-ion battery is relatively high, which is mainly a result of the charge/discharge capacity. Modern lithium-ion batteries are among the most efficient energy storage and supply systems.

In an electric vehicle, the lithium-ion battery pack returns almost all of the energy it has previously absorbed into the drive system. The efficiency factor for an electric powertrain is more than 90%. A fuel cell reaches an efficiency factor of more than 50%. The efficiency of an internal combustion engine is only 35 to 40% (tank-to-wheel). This is because most of the energy is converted to heat and lost. But combustion engines are not all that bad when compared to conventional light bulbs. The efficiency factor for an incandescent bulb is only 5%. In other words, 95% of the energy is lost and only 5% is used to actually light up the room.