Introduce battery failure warning

Analyzing the mutual ratio of battery failure alarm internal resistance increments is the core concept of battery failure early warning engineering. The best method for battery failure early warning is to select battery internal resistance with damage sign significance as the early warning parameter. This requires the change of internal resistance, that is, through self-comparison. Calculate the internal resistance increment quantitatively. However, this method has the following practical difficulties: 1) There are many factors that affect the accurate value of the internal resistance of the battery, especially the online operation of the internal resistance under irregular natural fluctuations, which makes it impossible to determine the internal resistance of the battery. Damage, and lead to the lack of reference value to calculate the internal resistance of the incremental self-comparison. 2) As mentioned above, the initial internal resistance of the battery cannot be accurately calibrated when it leaves the factory, making subsequent measurements and calculations lose the original basis; the only way to solve these difficulties is to replace the self-compared internal resistance increment with a battery pack The internal resistance increment compared with each other. The following prerequisites are required to implement this replacement. (1) Battery damage caused by battery differences, including damage caused by a vicious cycle, is often concentrated on a small number of batteries. In this way, the change of the internal resistance of most batteries will follow the aging law of the undamaged battery. The basic value of the internal resistance of the undamaged battery, the current that can be extracted refers to the internal resistance of the damaged battery, and then the difference between the current actual internal resistance value of each battery and the current reference internal resistance value can be defined as the mutual increase of internal resistance. Compare. As long as the installation and operation of the battery pack meet the above-mentioned conditions (generally the actual battery pack can meet), the replacement is reasonable enough. The important realistic goal of the replacement is to develop a practical instrument with technical feasibility. (2) The battery pack should work under the same working conditions, including the same current and the same temperature, and the online natural fluctuations of its internal resistance should have the same historical process, that is, the internal resistance value should also have a smaller operating distribution error . (3) The battery pack adopts the same manufacturer, the same specification, and is assembled according to certain specifications, including the consistency test before assembly and the balance charging procedure after assembly, and the initial distribution error of the internal resistance value is small. Evidence of damage Damage sign is an important new concept in battery damage theory, and it is an important problem in solving engineering applications. Among the changes in various physical quantities caused by battery damage, visible damage marks can be measured repeatedly, while those that cannot be directly and repeatedly measured are invisible damage marks. Obviously, the characteristics of obvious injury scars are exactly the same as the three characteristics of the best early warning parameters described in the introduction of this article. Therefore, looking for obvious injury scars is equivalent to looking for the best early warning parameters. 2.1 Technical problemResistance is a specific physical quantity, and there are many ready-made measurement methods. In knowledge, 4-wire communication method can effectively overcome the negative influence of wire resistance and contact resistance is the most ideal physical method to measure small resistance, but 4-wire The communication method developed into a practical early warning technology for battery failures is also facing many technical challenges. Since technical details are not the focus of this article, here is only a brief review. 2.1.1 Anti-online interference internal resistance online measurement is the basic requirement of battery failure alarm technology, that is, the internal resistance measurement when the battery and power supply equipment work together and on duty. The internal resistance of the large-capacity battery is very small. Basically, the lower limit of AC is measured by the 4-wire method. The resistance increase is nearly an order of magnitude less than the measured resistance. The operating power pulsation frequency of power equipment, switching noise, especially the strong crosstalk, will cause a lot of Measured value, defeating any anti-interference measures can reduce the negative impact of interference, and can't make it disappear. When the uncertainty of the interference jumps greater than the increase of the internal resistance, the measurement data will be lost. Statement: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete the previous article: Why lithium iron phosphate Can the battery achieve long life and low cost?