Why do remote instrument equipment batteries need a lithium-ion battery management system?

Due to their special working environment and working methods, remote instruments and equipment have high requirements on batteries. It requires a longer battery life, which usually lasts a year or more. Lithium-ion batteries have the advantages of high working voltage, small size, light weight, high energy density, no memory effect, no pollution, low self-discharge, and long cycle life. They are widely used in long-term standby remote monitoring instruments. Compared with nickel-metal hydride batteries, lithium-ion batteries are 30% to 40% lighter and have a 60% higher energy ratio. However, lithium-ion batteries also have serious drawbacks. In summary, there are the following two aspects: 1. Safety Li-ion batteries have defects such as poor safety and explosion. In particular, lithium cobalt oxide, as the negative electrode material of lithium-ion batteries, cannot discharge large currents and has poor safety. In addition, almost all types of lithium-ion batteries overcharge or overdischarge will cause irreversible damage to the battery. Lithium-ion batteries are also very sensitive to temperature: if used at too high a temperature, it may cause the electrolyte to decompose, burn or even explode. Low temperature will cause deterioration of lithium-ion battery performance and affect the normal use of equipment. Due to the limitation of battery manufacturing technology, the internal resistance and capacity of each battery will be different. When multiple 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, in actual use, lithium-ion batteries require a special protection system to monitor the health of the battery, so as to manage the use of lithium-ion batteries. Figure 1 shows the lithium ion battery after the electrolyte is decomposed. 2. Maintainability At low temperatures, the capacity decay and power of lithium-ion batteries cannot be accurately predicted, resulting in poor maintainability of the equipment. Long-term online electric meters need to replace the battery regularly, but the remote monitoring equipment workstations are scattered, and the distance between each site is large, so the workload of replacing the battery is large and the cost is high. In order to reduce maintenance workload and maintenance costs, the battery management system is required to have an accurate power state estimation function, accurately grasp the battery power state, and perform battery replacement work more specifically. At the same time, the battery management system is required to have low power consumption, reduce maintenance frequency, and extend battery life. Therefore, a reasonable design of the battery management system is of great significance to the maintenance of long-term continuous power supply remote monitoring instruments. However, due to the operating characteristics of remote monitoring instruments and the inherent characteristics of lithium-ion batteries, it is very difficult to develop a battery management system that meets the needs of such applications. The following factors are important: First of all, from the working characteristics of the remote measuring instrument, in order to reduce power consumption, the remote measuring instrument generally sleeps and wakes up regularly. This is the dynamic change of the working current, and the working current of waking up is much higher than the static state. , But the working time after waking up is much shorter than that in the dormant phase; secondly, the discharge curve of lithium-ion battery is very gentle, and the main charging is concentrated above 3.6v voltage. Then, as the voltage drops further, the battery power begins to drop sharply, and the remote meter cannot issue a low battery alarm based on the battery voltage. Finally, the self-discharge rate of lithium-ion batteries varies greatly with temperature fluctuations. For instruments working in the field, the temperature conditions are extremely extreme, which further increases the difficulty of battery power prediction. The current battery management system is difficult to adapt to the requirements of these functions and performance. This topic is proposed based on the above background. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.