What are the testing methods for UPS battery internal resistance?

How to test the internal resistance of UPS battery? Whether the battery is about to fail, the capacity is insufficient, or the battery is improperly charged and discharged, it can be reflected in the changes in its internal resistance. Therefore, the UPS battery internal resistance test can be used to evaluate its working status. At present, the common methods for measuring the internal resistance of batteries are: (1) Density method Density method mainly estimates 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 when it is re-floating. (3) DC discharge method The DC discharge method is to discharge the battery with an 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. (4) AC injection method The AC method determines the internal resistance R of the battery by injecting a constant AC current signal Is into the battery, measuring the voltage response signal vo at both ends of the battery, and the phase difference between the two. The method does not need to discharge the battery, and can realize the safe online detection of the internal resistance of the battery. Therefore, it will not affect the performance of the battery. This method needs to measure the most alternating current signal Is, the voltage response signal Vo. and the phase difference between voltage and current. Disclaimer: Some pictures and contents of articles published on this site are from the Internet. If there is any infringement, please contact to delete.