Study and realization on the internal impedance of single cell on-line detector

Impedance measurement is a method by which the condition of a battery may be assessed. The realization of on-line monitoring of internal resistance of single cell is important to improve the safe operation of the battery backup system. At present there are many internal resistance measuring methods, such as the density method, the terminal voltage method, the momentary load test method, etc. After compared and analyzed their advantages and disadvantages, a new method to measure internal resistance of single cell on-line is introduced, namely AC injection method. A new detector based on the proposed method is introduced. Experimental results have proved that the project is quite operational and effective.