Publications

Determination of battery stability with advanced diagnostics

Lamb, Joshua H.; Torres-Castro, Loraine T.; Orendorff, Christopher O.; Dufek, Eric J.; Walker, Lee K.; Ho, Chinh H.

Lithium ion batteries for use in battery electric vehicles (BEVs) has seen considerable expansion over the last several years. It is expected that market share and the total number of BEVs will continue to increase over coming years and that there will be changes in the environmental and use conditions for BEV batteries. Specifically aging of the batteries and exposure to an increased number of crash conditions presents a distinct possibility that batteries may be in an unknown state posing danger to the operator, emergency response personnel and other support personnel. The present work expands on earlier efforts to explore the ability to rapidly monitor using impedance spectroscopy techniques and characterize the state of different battery systems during both typical operations and under abusive conditions. The work has found that it is possible to detect key changes in performance for strings of up to four cells in both series and parallel configurations for both typical and abusive response. As a method the sensitivity for detecting change is enhanced for series configurations. For parallel configurations distinct changes are more difficult to ascertain, but under abusive conditions and for key frequencies it is feasible to use current rapid impedance techniques to identify change. The work has also found it feasible to use rapid impedance as an evaluation method for underload conditions, especially for series strings of cells.