Bewley, Randy L. | Search NASA

DOE OSTI2022

Electric vehicle post-crash Recovery—Stranded energy issues and mitigation strategy

In post-crash situations, passengers, bystanders, and first responders are exposed to the immediate safety risks of stranded energy in electric vehicle (EV) batteries. Stranded energy is the energy remaining inside any undamaged or damaged battery following an accident. A potentially damaged battery with an unknown state of safety might go into thermal runaway in the absence of proper monitoring, diagnostics, controls, and handling—thereby leading to potential loss of life and property damage. Therefore, it is imperative to develop standard guidelines, diagnostic methods, and tools to handle stranded energy appropriately and minimize safety risks from immediately after an EV accident to final disposal or re-entry to the road. This perspective paper identifies the challenges associated with handling stranded energy and proposes some potential solution pathways. Further, we hope to draw attention of the research and development community, original equipment manufacturers, and policymakers for motivating new insights and research needs in mitigating safety implications associated with stranded energy.

25 ENERGY STORAGE↗

DOE OSTI2021

Early Battery Performance Prediction for Mixed Use Charging Profiles Using Hierarchal Machine Learning

A key step limiting how fast batteries can be deployed is the time necessary to provide evaluation and validation of performance. Using data analysis approaches, such as machine learning, the validation process can be accelerated. However, questions on the validity of projecting models trained on limited data or simple cycling profiles, such as constant current cycling, to real-world scenarios with complex loads remains. Here, we present the ability to predict performance with less than 1.2% mean absolute percent error when trained on cells aged using complex electric vehicle discharge profiles, and either AC Level 2 charge or DC Fast charge profiles, using only the first 45 cycles, namely 5% of the total testing time. While error is low across the projections, this study also highlights that battery lifetime analysis using only cycling data may not extrapolate safely to certain real-world conditions due to the impact of calendar degradation.

25 ENERGY STORAGE↗