Probing lithium-ion batteries' state-of-charge using ultrasonic transmission - Concept and laboratory testing

Principle of the state-of-charge estimation by ultrasonic pulsed excitations: A RCN-pulse transmitted through the cell gives rise to two wave packets (wave I and II), where the slower (wave II) ones' amplitude shows a linear relationship on the state-of-charge. For optimized signal strength of-the-shelf piezo transducers are attached centered on opposite sides of commercial pouch-type cells.169