Inventor Daniel Steingart, Assistant Professor of Mechanical and Aerospace Engineering and the Andlinger Center for Energy and the Environment
What it does
The method detects a battery’s “acoustic fingerprint” to assess its level of charge and state-of-health. Unlike other methods, the technique does not deplete the battery’s charge and works while the battery is in operation. The technique potentially can be used for all battery types, from simple household batteries to ones capable of powering electric vehicles.
The inspiration for the technology came when a friend asked Steingart to check out a popular YouTube video showing that a depleted battery bounces higher than a fully charged one. Steingart and graduate student Shoham Bhadra found that there is indeed a relationship, albeit indirect, between bounciness and charge, suggesting a way to use the phenomenon to interrogate the charge-level and performance characteristics.
Bouncing a battery is similar to hitting it with a hammer — both actions cause sound waves to flow through the interior. The researchers measured how sound waves travel in different types of batteries, and found that each battery type has a distinct acoustic fingerprint. They also discovered that the acoustic fingerprint changes with the battery’s state-of-charge, so that a drained battery has a different sound profile than a charged one.
“We came up with a model describing this relationship between sound and battery health, and so far it has worked on every battery we’ve tried, regardless of shape or chemistry,” Steingart said.
The finding that sound travels differently through charged versus drained batteries is not surprising given how batteries work. Most batteries experience a change in internal structure as chemically stored energy transforms into electricity. For example, a common household battery contains zinc that converts into zinc oxide as the battery generates electricity. The zinc oxide particles link to each other via tiny bridges that act like a network of springs, giving the battery more bounce.
The researchers envision that the technology could be used by battery manufacturers for quality control, by electric-vehicle mechanics at auto-repair shops, and to help guide the research and development of better batteries for applications such as grid-scale electricity storage.
Collaborators Graduate student of electrical engineering Shoham Bhadra; Professor of Mechanical and Aerospace Engineering Clarence Rowley and Associate Professor of Electrical Engineering Jason Fleischer; postdoctoral research associate Andrew Hsieh in mechanical and aerospace engineering; former postdoctoral research associates Benjamin Hertzberg in mechanical and aerospace engineering and Alexandre Goy in electrical engineering; and 2015 graduate Peter Gjeltema.
Development status Patent protection is pending. Princeton is seeking industrial interest for further development of this opportunity.
Funding sources National Science Foundation, the U.S. Department of Energy’s Advanced Research Projects Agency, the Andlinger Center for Energy and the Environment, and Princeton E-ffiliates Partnership.