What are the technical parameters of the battery?

The electromotive force is the difference between the balanced electrode potentials of the two electrodes. Taking a lead-acid battery as an example, Eu003dФ+0-Ф-0+RT/F*In(αH2SO4/αH2O). Among them: E electromotive force Ф+0 positive electrode standard electrode potential, its value is 1.690Ф-0 negative electrode standard electrode potential, its value is -0.356R general gas constant, its value is 8.314T temperature, which is related to the temperature of the battery. F Faraday constant , Its value is 96500αH2SO4 the activity of sulfuric acid, which is related to the concentration of sulfuric acid. The activity of αH2O water is related to the concentration of sulfuric acid. It can be seen from the above formula that the standard electromotive force of a lead-acid battery is 1.690-(-0.0.356)u003d2.046V , So the nominal voltage of the battery is 2V. The electromotive force of lead-acid batteries is related to temperature and sulfuric acid concentration. 2. The rated capacity is the minimum capacity that the battery should be able to discharge under the conditions specified in the design (such as temperature, discharge rate, termination voltage, etc.). The unit is ampere hour and is represented by the symbol C. The capacity is greatly affected by the discharge rate, so the discharge rate is often indicated by Arabic numerals in the lower right corner of the letter C, such as C20u003d50, indicating that the capacity at 20 o'clock is 50 ampere hours. The theoretical capacity of the battery can be accurately calculated according to the amount of electrode active material in the battery reaction formula and the electrochemical equivalent of the active material calculated according to Faraday's law. Due to possible side reactions in the battery and special requirements during design, the actual capacity of the battery is often lower than the theoretical capacity. 3. The typical working voltage of a rated voltage battery at room temperature, also known as the nominal voltage. It is a reference when choosing different types of batteries. The actual working voltage of the battery varies with different usage conditions. The open circuit voltage of the battery is equal to the difference between the balanced electrode potentials of the positive and negative electrodes. It is only related to the type of electrode active material, and has nothing to do with the amount of active material. The battery voltage is essentially a DC voltage, but under certain special conditions, the phase change of metal crystals or certain phase-forming films caused by the electrode reaction will cause small voltage fluctuations. This phenomenon is called noise. The amplitude of the fluctuation is very small but the frequency range is very wide, so it can be different from the self-excited noise in the circuit. 4. Open circuit voltage The terminal voltage of a battery in an open circuit state is called open circuit voltage. The open circuit voltage of a battery is equal to the difference between the positive electrode potential and the negative electrode potential of the battery when the battery is open (that is, when no current flows through the two poles). The open circuit voltage of the battery is represented by Vopen, that is, Vopenu003dФ+-Ф-, where Ф+ and Ф- are the positive and negative electrode potentials of the battery, respectively. The open circuit voltage of a battery is generally less than its electromotive force. This is because the electrode potential established by the two poles of the battery in the electrolyte solution is usually not equal to the electrode potential, but to stabilize the electrode potential. Generally, it can be approximated that the open circuit voltage of the battery is the electromotive force of the battery. 5. Internal resistance The internal resistance of a battery refers to the resistance encountered when current passes through the interior of the battery. It includes ohmic internal resistance and polarization internal resistance, which also includes electrochemical polarization internal resistance and concentration polarization internal resistance. Due to the existence of internal resistance, the working voltage of the battery is always less than the electromotive force or open circuit voltage of the battery. The internal resistance of the battery is not constant. It changes constantly (increasing gradually) over time during the charging and discharging process. This is because the composition of the active material, the concentration of the electrolyte and the temperature are constantly changing. The ohmic internal resistance obeys Ohm's law, and the polarization internal resistance increases with the increase of the current density, but it is not a linear relationship. It is often added as the current density increases. Internal resistance is an important indicator that determines battery performance. It directly affects the battery's working voltage, working current, output energy and power. For batteries, the smaller the internal resistance, the better. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: How to use and maintain solar batteries?