Why do you need BMS lithium-ion battery management system?

Lithium-ion batteries are widely used in long-term standby remote monitoring instruments due to their high operating voltage, small size, light weight, high energy density, no memory effect, no pollution, small self-discharge, and long cycle life. Compared with nickel-metal hydride batteries, lithium-ion batteries are 30-40% lighter and have a 60% higher energy ratio. However, lithium-ion batteries also have serious shortcomings, which can be summarized in the following two aspects:

(1)Safety

Lithium-ion batteries have poor safety and have defects such as explosion. In particular, lithium-ion batteries using lithium cobalt oxide as the cathode material cannot be discharged under high current and have poor safety. In addition, overcharging or over-discharging almost all lithium-ion batteries will cause irreversible damage to the battery.

Lithium-ion batteries are also very sensitive to temperature: if the temperature is too high, it may cause the electrolyte to decompose, burn or even explode; if the temperature is too low, the performance of the lithium-ion battery will significantly deteriorate, affecting the normal use of the equipment.

Due to the limitations of the lithium-ion battery manufacturing process, the internal resistance and capacity of each battery will be different. When multiple lithium-ion batteries are used in series, the charge and discharge rate of each battery is inconsistent, resulting in low battery capacity utilization. In view of this, a special protection system is required to monitor the health of the battery during the actual use of lithium-ion batteries, so as to manage the use of lithium-ion batteries.

(2) Maintainability

At low temperatures, capacity fading and power cannot be accurately predicted, which makes the equipment less maintainable. Instruments that are online for a long time need to be replaced regularly, and remote monitoring equipment works in dispersed locations, and the distance between each location is long, so replacing batteries requires a lot of work and costs.

In order to reduce the maintenance workload and maintenance costs, the lithium-ion battery management system must have an accurate state-of-charge estimation function, accurately grasp the state of charge of the lithium-ion battery, and perform battery replacement in a more targeted manner. At the same time, the lithium-ion battery management system must have lower power consumption to reduce maintenance frequency and extend battery life. Therefore, the reasonable design of lithium-ion battery management system is of great significance for the maintenance of remote monitoring instruments that continuously supply power for a long time.