Sensitive strain-based soc and soh monitoring of battery cells

A battery pack comprising:

• first, second, and third adjacent battery cells;
• a strain gauge positioned between the first and second battery cells;
• and
• a stress concentrator positioned between the strain gauge and one of the first and second battery cells;
• the stress concentrator having a first surface contacting the strain gauge and a second surface opposite the first surface, the first surface having a smaller area than the second surface.

A strain-based state-of-charge monitoring system, comprising:

• first and second adjacent battery cells;
• a strain gauge and a stress concentrator positioned between the first and second battery cells;
• the stress concentrator having a first surface contacting the strain gauge and a second surface opposite the first surface, the first surface having a smaller area than the second surface;
• and
• a controller in communication with the strain gauge and configured to receive strain data therefrom.