What are the common methods for measuring the internal resistance of a battery?

At present, the common methods for measuring the internal resistance of batteries are: (1) Density method Density method is mainly used to estimate the internal resistance of the battery by measuring the density of the UPS battery electrolyte. It is often used for the internal resistance measurement of open lead-acid batteries and is not suitable for sealing lead-acid. The internal resistance of the battery is measured. The applicable range of this method is narrow. (2) Open-circuit voltage method The open-circuit voltage method estimates the internal resistance of the battery by measuring the terminal electrical version of the battery, and the accuracy is very poor. It even draws wrong conclusions. Because even a battery whose capacity has become very small, its terminal voltage may still behave normally in the floating charge state. (3) Direct current discharge method The direct current discharge method is to discharge the battery with instantaneous high current, measure the instantaneous voltage drop on the battery, and calculate the internal resistance of the battery by Ohm's law. Although this method has been widely used in practice, it also has some shortcomings. If this method is used to detect the internal resistance of the battery, it must be done in a static or offline state, and online measurement cannot be achieved. Moreover, high-current discharge will cause greater damage to the battery, thereby affecting the maximum capacity and life of the battery. The UPS battery internal resistance test can prolong the service life of the battery pack. Battery voltage, current, and temperature are important operating parameters of the UPS battery, but they cannot reflect the internal state of the battery. Internal resistance, as the most effective and most convenient performance parameter for batteries currently internationally recognized, can reflect performance indicators such as the degradation degree and capacity status of the battery, and these indicators cannot be reflected by operating parameters such as voltage, current, 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: What are the differences between power lithium batteries and capacity lithium batteries?