Measuring Individual Battery Dimensional Changes for State-of-Charge Estimation using Strain Gauge Sensors

This investigation has studied the correlation of Lithium-Ion battery dimensional changes (e.g., strain measurement) to the real-time State-of-Charge (SOC) by mounting strain gauges on the cases of battery cells. Strain gauges are used to determine whether the measured strain profiles during constant-current-constant-voltage (CCCV) cycles contain useful information that can be correlated with the SOC. Attention has been focused on investigating the battery dimensional change polarization following a current event to determine whether it holds promise for increasing the battery pack's total energy throughput by avoiding the rest time required when using the open-circuit voltage for SOC estimation. The experimental results confirm that the strain gauges generate output voltages that track the SOC profile during dynamic charge/discharge events. The results also demonstrate that tracking battery dimensional changes holds potential for significantly reducing the rest time that is currently required for estimating SOC in many applications.