Remote instrumentation equipment has very high requirements on batteries due to its special working environment and working methods. It requires the battery to have a long continuous power supply capability, and the battery life often needs to reach 1 year or more. Lithium batteries are widely used in long-term standby remote monitoring instruments due to their many advantages such as 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, but their energy ratio is 60% higher. However, lithium batteries also have serious defects. In summary, Shenzhen lithium batteries have the following two aspects: (1) Safety Lithium batteries have defects such as poor safety and occasional explosions. In particular, lithium batteries with lithium cobalt oxide as the cathode material cannot be discharged at high currents and have poor safety. In addition, overcharging or overdischarging almost all types of lithium batteries can cause irreversible damage to the cells. Lithium batteries are also extremely sensitive to temperature: if used at too high a temperature, it may cause the electrolyte to decompose, burn or even explode; if the temperature is too low, the performance of the lithium battery will significantly deteriorate, affecting the normal use of the equipment. Due to the limitations of the battery manufacturing process, the internal resistance and capacity of each battery unit will vary. When multiple battery units are used in series, the charge and discharge rates of each battery cell will be inconsistent, which leads to low utilization of battery capacity. In view of this, lithium batteries usually require a specialized protection system to monitor the health status of the battery during actual use to manage the use process of lithium batteries. (2) Maintainability The capacity fading of lithium batteries at low temperatures and the inability to accurately predict the power level make the maintainability of the equipment poor. Instruments that are online for a long time require regular battery replacement, and the working sites of remote monitoring equipment are scattered and the distances between sites are long, so battery replacement is a huge workload and costly. In order to reduce the maintenance workload and reduce maintenance costs, the battery management system needs to have an accurate charge state estimation function to accurately grasp the battery's charge state and perform battery replacement more purposefully; at the same time, the battery management system also needs to have a lower charge state. own power consumption to reduce maintenance frequency and extend battery life. Therefore, for remote monitoring instruments that are continuously powered for a long time, a reasonable design of the battery management system is of great significance to the maintenance of the equipment. However, the working characteristics of remote monitoring instruments and the inherent characteristics of lithium batteries make it quite difficult to develop a battery management system that meets the requirements of such applications. Lithium battery manufacturers have the following factors: First of all, from the working characteristics of remote measuring instruments, in order to reduce power consumption, remote measuring instruments generally sleep and wake up periodically. Its working current changes dynamically, and the wake-up phase The operating current is much higher than the sleep state, but the working time in the wake-up phase is much shorter than the sleep phase; secondly, the discharge curve of the lithium battery is very gentle, and the main power is concentrated above the 3.6V voltage, and then, as the voltage further decreases , the battery power begins to drop sharply, and the remote instrument equipment cannot issue a low battery alarm based on the battery voltage; finally, the self-discharge rate of lithium batteries changes greatly with temperature fluctuations. For instrument equipment working in the field, the temperature conditions are very extreme. This further increases the difficulty of battery power prediction. Existing battery management systems are difficult to adapt to these functional and performance requirements. This topic is proposed based on the above background.

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