As demand for electric vehicle batteries continues to grow, researchers have developed a method for predicting how changes to manufacturing processes and materials will impact battery life.

U-M engineers have identified internal resistance, measured immediately after cells are made, as a key indicator of how long a battery will last. The measurements can be done in just seconds at the tail end of the manufacturing process at little to no additional cost.

Previous research has shown lifespan prediction is possible, but it requires repeated cycling — charging, discharging and recharging — in order to gather data needed to train the algorithm. Aging tests needed to determine lifespan can take weeks to months to complete. For this reason, the tests are performed to only a few cells and not all the cells produced.

But the new study, recently published in Joule, shows that accurate battery lifetimes can be predicted with the help of one resistance measurement, or a measure of how much the battery fights the flow of current inside it. That resistance can come from the materials used for internal components, or electrochemical factors that affect how well ions move between the battery electrodes. Measuring resistance at low levels of charge is key.

«The resistance measurement, at low state of charge, can, in principle, be obtained without any cycling, making the model training process much faster,» said Andrew Weng, a doctoral student in mechanical engineering and the study’s lead author.

Why is resistance such a good barometer for battery life estimates?

Story Source: Materials provided by University of Michigan. Note: Content may be edited for style and length.