When it comes to lithium batteries, it is often associated with terms like lithium battery protection board, battery management system (BMS), and more. As we all know, BMS is mainly used in lithium batteries, whereas lead-acid batteries generally do not have this management system. Compared with lead-acid batteries, lithium batteries need an additional BMS to protect the core. So, what is lithium battery BMS?
The BMS battery management system is the link between the battery and the user, mainly aimed at secondary batteries. Its function is to enhance the use efficiency of the battery, prevent overcharging and discharging, and increase the battery's service life by monitoring the battery's status. In simple terms, it is like an operating system designed for managing, operating, and using a lithium battery group. The BMS industry is in the midstream of the power lithium battery industry chain, which includes four parts: upstream raw materials, BMS module, BMS finished product, and downstream application.
BMS is known as the "brain" of the power battery operating system, which functions like the battery's brain, receiving and sending the battery and external ports' information, deeply analyzing and processing the information, and then transmitting the executing work command. Given its critical impact on new energy vehicles, the BMS industry continuously attracts a large number of lithium battery manufacturers.
Now that we know what the lithium battery BMS is, why is it needed? Lithium batteries have a high working voltage, small size, lightweight, high energy density, no memory effects, no pollution, small self-discharge, and long cycle life. Consequently, they have been widely used in long-time standby remote monitoring instruments. Compared with nickel-metal hydride batteries, lithium-ion batteries are 30%-40% lighter and have a 60% higher energy ratio. However, lithium batteries also have significant defects that can be summarized in two aspects:
Lithium-ion batteries lack safety and have defects such as explosions. In addition, lithium-ion batteries using lithium cobalt oxide as the positive electrode material cannot discharge with large currents and have poor safety. Also, almost all overcharged or over-discharged lithium-ion batteries cause irreversible damage to the battery.
Lithium-ion batteries are sensitive to temperature: if used at high temperatures, the electrolyte may decompose, burn, or even explode; if the temperature is too low, the lithium-ion battery's performance will significantly degrade, affecting normal device use.
Due to the limitations of lithium battery manufacturing processes, each battery's internal resistance and capacity may vary. When multiple lithium batteries are used in series, each battery's charging and discharging rate differs, resulting in a low battery capacity utilization rate. Therefore, a special protection system is needed in the practical application of lithium batteries to monitor the battery's health and manage the use of lithium-ion batteries.
In a low-temperature environment, capacity attenuation and power cannot be accurately predicted, reducing the equipment's maintainability. Instruments that are online for an extended period require regular replacement, and remote monitoring equipment works in dispersed locations with long distances between each site, resulting in a large workload and high costs for battery replacement.
For reducing maintenance workload and costs, the lithium battery management system should have an accurate estimation of the electricity state and accurately grasp the lithium battery's electricity state and carry out battery replacement work accordingly. Moreover, the lithium battery management system should have low power consumption to reduce maintenance frequency and extend battery life. Therefore, it is of significant importance to rationally design a lithium battery management system for maintaining remote monitoring devices that require prolonged and continuous power supply.