Analysis of the principle and method of lithium iron phosphate battery power test

Advanced lithium iron phosphate batteries generally have a battery control chip, such as the linear lithium battery chip SL1053. This is to control battery charge and discharge, battery overload protection, and decompose voltage data to estimate battery temperature. It is equivalent to a high-end fuse, basically relying on this chip to read the power, rather than straightly decomposing the voltage to convert the power. Sometimes the battery chip will fail, such as instantaneous high voltage destroying the chip, which will cause the battery to be displayed incorrectly and cannot be charged. In many cases, the battery problem is caused by the chip. Lithium iron phosphate battery power test methods: 1. Voltage detection method: That is to say, the power of lithium iron phosphate battery is obtained by simply monitoring the battery voltage. The battery power and voltage are not linearly related, so the detection method is not accurate, and the power measurement accuracy is only more than 20%. Especially when the battery power is less than 50%, the power calculation of the mobile phone will become very inaccurate. Therefore, the protection of the battery by this method is very limited. 2. Battery modeling method: This method is to build a data table based on the discharge curve of the lithium battery. The data table will indicate the power value under different voltages. This method can effectively improve the accuracy of the measurement. But it is not easy to obtain an accurate data sheet, because the relationship between voltage and power also involves factors such as battery temperature, self-discharge, and aging. Only by combining many factors to make corrections can a more satisfactory electric quantity measurement be obtained. 3. Coulomb counter: The coulomb counter is a current check resistor in the positive and negative poles of a lithium battery. When a current flows through the resistor, Vsense will appear. By testing Vsense, the current flowing through the battery can be calculated. From the above three methods, we can see that the accuracy of the coulomb meter is the highest. It can reduce the discharge cut-off voltage of the battery without damaging the lithium iron phosphate battery, so that the battery capacity can be used to the maximum, especially regarding Low-voltage systems and batteries that are used many times. In addition, it can send out a warning message of low lithium battery power with higher accuracy to warn users from losing data during use. 1. Charge the battery. I originally intended to calculate the battery's charge capacity by testing the battery voltage Vbat; 2. When the 5V adapter is connected, the main control board will output 4.2V Vbat, and the battery capacity is already 100%. The parameter that expresses the energy storage size of lithium batteries is energy density, which is approximately equivalent to the product of voltage and lithium battery capacity in value. In order to effectively increase the storage capacity of lithium batteries, people generally use the method of increasing battery capacity to achieve their goals. However, due to the nature of the raw materials used, the capacity increase is always limited, so increasing the voltage value becomes another way to improve the storage capacity of lithium batteries. As we all know, the nominal voltage of a lithium battery is 3.6V or 3.7V, and the highest voltage is 4.2V. So, why can't the voltage of the lithium battery get a greater breakthrough? After all, this is also determined by the material and structural properties of the lithium battery. The voltage of a lithium battery is determined by the electrode potential. Voltage, also known as potential difference or potential difference, is a physical quantity that weighs the energy difference of electric charges in an electrostatic field due to different potentials. The electrode potential of lithium ions is about 3V, and the voltage of lithium batteries varies with different materials. For example, a general lithium battery has a rated voltage of 3.7V and a full-charge voltage of 4.2V; while a lithium iron phosphate battery has a rated voltage of 3.2V and a full-charge voltage of 3.65V. In other words, the potential difference between the positive electrode and the negative electrode of a lithium battery in practical use cannot exceed 4.2V, which is a requirement based on material and use safety. 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.