Existing EV batteries may last up to 40% longer than expected due to an unrealistic test discharge profile of steady use

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"... batteries still account for almost a third of the price of a new EV ...

The researchers designed four types of EV discharge profiles, from the standard constant discharge to dynamic discharging based on real driving data. The research team tested 92 commercial lithium-ion batteries for more than two years across the discharge profiles. In the end, the more realistically the profiles reflected actual driving behavior, the higher EV life expectancy climbed. ...

For example, the study showed a correlation between sharp, short EV accelerations and slower degradation. This was contrary to long-held assumptions of battery researchers, including this study’s team, that acceleration peaks are bad for EV batteries. ..."

From the abstract:

"Laboratory ageing campaigns elucidate the complex degradation behaviour of most technologies. In lithium-ion batteries, such studies aim to capture realistic ageing mechanisms to optimize cell chemistries and designs as well as to engineer reliable battery management systems. In this study, we systematically compared dynamic discharge profiles representative of electric vehicle driving to the well-accepted constant current profiles. Surprisingly, we found that dynamic discharge enhances lifetime substantially compared with constant current discharge. Specifically, for the same average current and voltage window, varying the dynamic discharge profile led to an increase of up to 38% in equivalent full cycles at end of life. Explainable machine learning revealed the importance of both low-frequency current pulses and time-induced ageing under these realistic discharge conditions. This work quantifies the importance of evaluating new battery chemistries and designs with realistic load profiles, highlighting the opportunities to revisit our understanding of ageing mechanisms at the chemistry, material and cell levels."

Existing EV batteries may last up to 40% longer than expected | Stanford Report "Consumers’ real-world stop-and-go driving of electric vehicles benefits batteries more than the steady use simulated in almost all laboratory tests of new battery designs, Stanford-SLAC study finds."

Dynamic cycling enhances battery lifetime (open access)

Fig. 2: Dynamic discharge profiles lead to a wide range of degradation profiles.