Factors affecting internal resistance of storage battery

2023-04-24

      Factors affecting internal resistance of storage battery      


1. The internal resistance of the battery consists of ohmic polarization (conductor resistance), electrochemical polarization and concentration polarization resistance. During the charging and discharging process, the resistance changes, and the internal resistance changes from large to small, on the contrary, the internal resistance increases.


2. The temperature also has a great influence on the internal resistance of the battery. If the temperature is below 0 ℃, the internal resistance will increase by about 15% every time the temperature drops by 10 ℃. One of the important reasons is that the specific resistance is increased because the viscosity of sulfuric acid solution becomes larger. At higher temperature, such as above 10 ℃, when the diffusion rate of sulfate ion increases, the concentration polarization effect will be significantly reduced, and the polarization resistance will decrease, but the conductor resistance will increase with the increase of temperature, but the rate of increase is small.


3. The internal resistance of the battery is related to the size of the discharge current. For the instantaneous large current discharge, the sulfuric acid solution in the electrode plate gap is rapidly diluted, and the sulfuric acid molecules in more than 90% of the solution outside the electrode plate hole have no time to diffuse into the electrode plate gap. In this way, the specific resistance of the solution in the plate hole increases and the terminal voltage decreases significantly. However, after the discharge is stopped, the specific resistance of the solution in the plate hole decreases and the terminal voltage rises as the sulfuric acid molecules with high concentration diffuse into the plate gap.


4. In addition, the internal resistance of thin plate battery is obviously smaller than that of thick plate battery, because the number of thin plates of the same capacity battery is more than that of thick plate battery, so when the same current is discharged, the current density of thin plate battery is small, and the polarization of each pole is much smaller.



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