Why should electric vehicles have a BMS system?

BMS system is mainly used in secondary batteries, especially for the current mainstream use of lithium-ion battery electric new energy vehicles is particularly important. No matter what kind of lithium-ion battery is used by the vehicle, the power battery is composed of a small battery cell through a series, parallel way to form a battery pack, and then the battery pack finally forms the power battery unit of the vehicle.

What really plays the role of energy storage in the battery pack is each small battery cell in the battery pack, such as the 18650 lithium-ion battery used, the number represents the specification of each battery cell: the diameter is 18mm, the length is 65mm. An 85kW · h version of the Tesla Model S carries a power battery unit consisting of nearly 7,000 18650s.

Each small cell is made individually. And because of the electrochemical characteristics of the battery, the energy storage consistency of the secondary lithium-ion battery after leaving the factory is different. When charging, all batteries are charged from a charging port, how to ensure that each battery is fully charged, and will not cause damage to the battery because of overcharging? This is the BMS system to solve the problem.