Why can't the electric vehicle battery accurately display the remaining power?

Why does the battery of an electric vehicle not accurately display the remaining power? Back to the original question, then, why does the power lithium-ion battery (including lithium battery and lead battery) of the electric vehicle look inaccurate? This is because the power lithium-ion battery of the electric vehicle The charge level of a battery (usually called SOC, state of charge) is more difficult to measure than that of a mobile phone. From several perspectives, the above explains why the remaining power of electric vehicles is more difficult to estimate than that of mobile phones. Below, from a deeper perspective, some points are put forward: Commonly used SOC (remaining power) estimation methods: Let us start with one we know better: GPS. Now, GPS positioning based on mobile phones is accurate, accurate to the order of meters. As far as missiles are concerned, such positioning is not enough. Two things are missing: accuracy and real-time (that is, it takes a few seconds to successfully locate). So the missile has another system to compensate: a gyroscope. Compared with satellite GPS positioning, gyroscopes have completely complementary characteristics. They are accurate (at least on the millimeter scale) and real-time, but the problem is that errors are cumulative. For example, if you blindfold a person and ask him to walk in a straight line, you may not see a distance of tens of meters, but you may also be able to walk several kilometers and turn the direction 180 degrees. Is there a way to fuse information between GPS and gyroscope to complement each other to obtain the most accurate and accurate position? The answer is yes, the Kalman filter algorithm is good, that's it, nothing else. What kind of relationship does this have to estimate the SOC of the battery? There are two other common SOC measurement methods: the first is the open circuit voltage method, which measures the state of the battery according to the open circuit voltage of the battery. This is easy to understand, but the high battery voltage is fully charged, and the low battery power is the corresponding relationship between power and voltage. This approach is similar to satellite GPS positioning without accumulated error (because it is condition-based), but the accuracy is low (due to various factors, the previous response has now been explained). The second is called ampere-hour integrator, which measures the state of the battery by integrating the voltage (flow) of the battery. For example, if you charge a 100-kilowatt battery and you measure the current every time and add it to 50 degrees, the remaining power is 50 degrees. This method can be compared to a gyroscope with high accuracy (the accuracy of instantaneous measurement is less than 1%, and 0.1% of the measurement is cheap and common), but the cumulative error is very large. In addition, even if the ammeter is a god brand and completely accurate, the hourly integral method of the ammeter is inseparable from the open circuit voltage method. Why? Because the nature of the battery itself will change. Academically, maybe some advanced automobile companies combine the open circuit voltage method and the ampere-hour integration method through the Kalman filter algorithm to get the most accurate SOC estimation, but they often make mistakes because they don’t know how to deepen the continuous changes in the battery. The nature of evolution. The electric vehicles developed by domestic automobile companies generally use the open circuit voltage method and the lamv integral method: the following car has left enough time (for example, the car is only turned on in the morning), and the open circuit voltage method is used to estimate the power start, which is represented by SOC_start. After the car is started, the battery status becomes chaotic, and the open circuit voltage method is no longer valid. Then, the amv integral method based on SOC_start is used to estimate the current battery power. An important factor that makes the SOC of electric vehicles difficult is the difficulty of modeling the battery pack itself. Perhaps, in other words, the research field of SOC estimation of electric vehicles can be made more and more accurate. The essence of batteries and battery packs is the key direction. Improving instrument accuracy is not the current research direction is accurate enough, and then accuracy is not useful. of. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete it. Previous: Can the battery handling APP truly extend the battery life of the mobile phone?