Online detection of terminal voltage in Li-ion batteries via battery impulse response

Lithium-ion batteries exhibit high levels of energy and power density among electrochemical batteries. This attribute makes them suitable for being selected as the energy storage system in electric, hybrid electric vehicle, and plug-in vehicles (EV/HEV/PHEV). One of the important issues in automotive batteries is to monitor their online state-of-charge (SOC) and state-of-health (SOH). Open circuit voltage, as one parameter used for predicting the SOC in the battery, is not readily available during charge and discharge cycles. In this paper a new method for prediction of the terminal voltage in Li-ion batteries based on using the impulse response has been proposed. By obtaining the impulse response of the Li-ion battery, one can use the terminal current measurement to predict the output voltage of the battery. Online comparison of the predicted and measured terminal voltage provides a tool for online monitoring of the SOH and SOC.