Ohm internal resistance test for power battery

Ohm internal resistance for power storage battery was measured based on the step-current testing principle and by means of the general charge-discharge instruments.The tolerance of this measuring method was ±5%.At the same time,the following rules were observed:(1) battery internal resistance was almost constant while DOD﹥30%;(2) 80% of the voltage decrease of battery was caused by ohm internal resistance when battery was discharged at large current.