What are the performance indexes of lead-acid batteries?

The performance index of the lead-acid battery: open circuit voltage and working voltage 1.1 open circuit voltage The terminal voltage of the battery in the open circuit state is called the open circuit voltage. The open circuit voltage of the battery is equal to the difference between the positive electrode potential and the negative electrode potential of the battery. 1.2 Working voltage Working voltage refers to the voltage displayed during the discharging process after the battery is connected to the load, also known as the discharging voltage. The operating voltage at the beginning of the battery discharge is called the initial voltage. After the battery is connected to the load, the operating voltage of the battery is lower than the open circuit voltage due to the existence of ohmic resistance and polarization overpotential. 2 The amount of electricity that a capacity battery can give under certain discharge conditions is called the capacity of the battery, which is represented by the symbol C. The commonly used unit is ampere hour, abbreviated as ampere hour (Ah) or milliampere hour (mAh). The battery capacity can be divided into theoretical capacity, rated capacity, and actual capacity. The theoretical capacity is the highest theoretical value obtained by calculating the mass of the active material according to Faraday's law. In order to compare different series of batteries, the concept of specific capacity is commonly used, that is, the theoretical power that a unit volume or unit mass battery can give. The unit is Ah/1 or Ah/kg. The actual capacity refers to the amount of power that the battery can output under certain conditions. It is equal to the product of the discharge current and the discharge time, the unit is Ah, and its value is less than the theoretical capacity. The rated capacity is also called the guaranteed capacity, which is the minimum capacity that the battery should discharge under certain discharge conditions according to the standards promulgated by the state or relevant departments. 3 Energy The energy of a battery refers to the electrical energy that the battery can give under a certain discharge system, usually expressed in watt-hours (Wh). The energy of the battery is divided into theoretical energy and actual energy. The theoretical energy W theory can be expressed by the product of the theoretical capacity and the electromotive force (E), that is, the actual energy of the battery is the product of the actual capacity C real and the average working voltage U flat under certain discharge conditions, that is, W real u003d C real U usually compares different battery systems by specific energy. Specific energy refers to the electric energy that a battery can output per unit mass or unit volume, and the unit is Wh/kg or Wh/l, respectively. Specific energy is divided into theoretical specific energy and actual specific energy. The former refers to the energy that can theoretically be output when the reaction material of the lkg battery is completely discharged. The actual specific energy is the actual energy output by the reacting substance of the lkg battery. Due to the influence of various factors, the actual specific energy of the battery is much smaller than the theoretical specific energy. The relationship between actual specific energy and theoretical specific energy can be expressed as follows: W real: W rational KVKRKm where Kv-voltage efficiency; KR-reaction efficiency; Km mass efficiency. Voltage efficiency refers to the ratio of the operating voltage of the battery to the electromotive force. When the battery is discharged, due to electrochemical polarization, concentration polarization and ohmic voltage drop, the operating voltage is less than the electromotive force. The reaction traffic usability indicates the utilization rate of the active material. The specific energy of the battery is a comprehensive index, which reflects the quality level of the battery, and also indicates the technology and management level of the manufacturer. 4 Power and specific power The power of a battery refers to the amount of energy given by the battery in a unit of time under a certain discharge system, and the unit is W (watt) or kW (kilowatt). The power that a unit mass storage battery can give is called specific power, and the unit is W/kg or kW/kg. Specific power is also one of the important performance indicators of batteries. A battery is larger than the power, which means that it can withstand high current discharge. The specific energy and specific power performance of the battery are important parameters when selecting the battery. Because the battery needs to be matched with the electrical equipment, meters, electrical machines, etc., in order to meet the requirements, the battery type must first be selected according to the required power of the electrical equipment. Of course, the final determination of the type of battery should also consider factors such as quality, volume, specific energy, temperature range and price. 5 Internal resistance The internal resistance of a battery includes ohmic internal resistance and polarization internal resistance, and polarization internal resistance includes electrochemical polarization and concentration polarization. The existence of internal resistance makes the terminal voltage of the battery lower than the electromotive force and open circuit voltage of the battery when discharging, and the terminal voltage is higher than the electromotive force and open circuit voltage when charging. The internal resistance of the storage battery is not constant, and it changes continuously over time during the charging and discharging process, because the composition of the active material and the concentration of the electrolyte are constantly changing. The ohmic resistance obeys Ohm's law; the polarization resistance increases with the increase of the current density, but it is not a linear relationship, and it often changes continuously with the current density and temperature. 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 charge the Ni-MH battery pack for the first time?