‘Mileage doesn’t matter’ on EV battery health

EV battery health has made ‘remarkable’ progress in the last 10 years and mileage is of ‘minimal’ relevance to long-term degradation according to a new report.

The latest data from battery health specialists Generational shows that in the last decade, battery technology has improved significantly, with batteries now retaining 10% more of their usable capacity at the same mileage.

The latest testing compared vehicles from 2016/17 with those from 2022/23. It found that at 90,000 miles the older cars had an average battery health of 75.87%, with 2023 vehicles recording an average of 86% – demonstrating the significant improvement in new vehicles’ battery longevity.

Data from lower-mileage vehicles shows similar results, with more modern cars losing less capacity at the same mileage. At 50,000 miles, EVs from 2023 recorded on average more than 5% higher battery health than 2016/17 models. Cars from 2019/20 vehicles achieved almost 5% higher than the 2016-2017 EVs at the same mileage.

The figures suggest that technological advances in recent years mean that vehicles’ batteries are more resilient than before and their systems are better able to manage and protect them from damage.

Generational’s CEO, Oliver Phillpott, said the latest findings reinforced the need for an easy-to-use system to help buyers and sellers to understand battery health and degradation and make informed decisions when buying a used EV.

He said: “The results of our EV battery health testing highlight the remarkable progress in battery technology over recent years, and just how much more value it adds than the mileage figure when looking to acquire a used EV. Understanding this evolution helps buyers make informed decisions based on their specific needs.

“As with combustion-engine vehicles, used EV customers want to be able to determine which vehicle will be the best for their needs; for some buyers, vehicles with moderately lower battery health may offer excellent value – they just need the right information to arrive at that conclusion. That’s what battery health certification provides, and what’s needed to create a healthy, sustainable market for used EVs.”

Polestar recently announced it would issue battery health certificates with all approved secondhand Polestar 2s, and auctioneer BCA provides a similar health check with EVs passing through its system. However, there is still no single agree industry-wide reporting system in place.

Battery longevity is frequently raised as a concern around EVs but the latest research from Generational backs up reports from Geotab last year that suggested modern EVs lose just 1.8% usable capacity per year – down from 2.3% in 2019.

A recent study at Stamford University also suggested that real-world use could mean batteries last even longer than lab testing suggests.

It found that the varied nature of real-world driving, including stop-start driving, different rates of acceleration, regenerative braking, and uneven charging and discharging patterns could be better for batteries than the constant-rate charge/discharge cycles used in lab testing. It suggests batteries may last 40% longer in the real world than lab testing suggests.