Battery management system, abbreviation BMS, it’s a system to manage the battery, usually has the function of measuring the battery voltage, to prevent or avoid the battery over discharge, over charge, over temperature... And other abnormal conditions. With the development of technology, many functions have been gradually added.
Common applications of BMS：Mobile phone, MP3 player, recording pen, notebook computer, electric bicycle , electric scooter, electric two-wheeler, electric locomotive, old people's scooter, pure electric car, electric car, electric boat, etc.
Power lithium battery management system can effectively monitor, protect, energy balance and fault warning for lithium battery pack, thus improving the working efficiency and service life of the whole power battery pack. Due to its high working voltage, small size, light weight, high energy density, no memory effect, no pollution, small self-discharge, long cycle life and many other advantages, it is widely used in various precision equipment. However, lithium batteries have serious defects, which can be summarized in the following two aspects:
1. Lithium batteries have poor safety, explosion and other defects. Especially the battery is of lithium cobalt oxide as a cathode electrode, it can’t discharge large current and has poor safety. In addition, almost all types of lithium batteries can cause irreversible damage to the cell by overcharging or over-discharging. Lithium batteries are also extremely sensitive to temperature: if used at too high a temperature, it may cause electrolyte decomposition, combustion and even explosion; Too low temperature will lead to lithium battery performance significantly deteriorated, affecting the normal use of equipment. Due to the limitations of battery manufacturing technology, the internal resistance and capacity of each cell will be different. When multiple battery units are used in series, the charging and discharging rates of each cell are inconsistent, which leads to the low utilization rate of battery capacity. In view of this, in the actual use of lithium battery, special protection system is usually needed to monitor the health status of the battery, so as to manage the use of lithium battery.
2. At low temperature, the capacity decay and power of lithium battery cannot be accurately predicted, so the maintainability of the equipment is poor. Long-term online meters need to change the battery regularly, while remote monitoring equipment work sites are scattered and the distance between sites is long, so the battery replacement work is huge and expensive. In order to reduce the maintenance workload and cost, lithium battery management system is required to have accurate charge state estimation function to accurately grasp the charge state of the battery and carry out battery replacement work more purposefully. At the same time, the battery management system is required to have low power consumption, so as to reduce the maintenance frequency and extend the service life of the battery.