How to Monitor for Rapid Temperature Increases in Battery Cells

The optimal function of Li-ion batteries is confined to restrictive temperature and voltage windows. Internal faults can initiate heating, triggering a positive feedback loop that results in thermal runaway. The worst case scenario resulting from this is an explosive hazard and potential harm to lives.

Current monitoring techniques are generally limited to battery management systems that utilize a few discrete single-point sensors. Scaling up of sensor count with higher capacity packs is typically prohibitive, and research into the detection of the onset of failure focuses largely on internal modifications to the cells themselves.

A safer, more powerful and cost effective solution to detect and provide warning of battery faults well in advance of failure is necessary. Luna engineers performed research where dielectrically insulated fiber optic sensors were integrated into battery packs and assemblies to monitor for rapid increases in temperature at the level of individual cells. Additionally, their test setup was also used to monitor for increases in strain consistent with pack swelling.

This research will be presented during the "Li-Ion Battery Monitoring And Early Failure Detection Using Distributed Fiber Optic Sensing" session June 20 as part of the Battery Electric Vehicle Architectures (BEVA) Congress.