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Here we report a novel and simple method for triggering internal short circuit (ISC) in Li-ion cells on demand and measuring critical ISC parameters in situ. The method works by inserting a pair of metal pads into a Li-ion cell and connecting the pads outside the cell through a switch and a current sensor. Different types of ISC that are common in field failures can be simulated by this method. ISC current and ISC resistance can be measured. The measurement further enables determination of local ISC heat generation rate. By attaching a micro temperature sensor between the metal pads, the ISC temperature can be also measured. The method was applied to both lab-made single-layer cells and commercially available multiple-layer cells in this work. The results generally verified previous modeling predictions about the effects of ISC types and ISC resistance on behaviors of Li-ion cells. It suggested that the proposed method can be used to validate models and enhance understanding of highly localized and transient behaviors of ISC. It was also demonstrated that the method has minimal effects on Li-ion cell performance and has good repeatability in triggering ISC.