Battery degradation remains one of the biggest questions for fleets considering electric vehicles. To better understand how EV batteries are holding up in real-world fleet operations, Geotab analyzed data from more than 22,000 electric vehicles operating across multiple industries and applications. In a recent interview, Charlotte Argue, senior manager of sustainable mobility at Geotab, said the study looked at 21 vehicle models, primarily light-duty vehicles, SUVs, vans, and a small number of heavy-duty trucks. The study found average battery degradation rates of about 2.3% per year. “So after eight years you’re still getting about 82% of your total capacity, which is pretty good,” Argue explained. Charging Habits Produced One of the Biggest Surprises One of the more surprising findings involved charging behavior. Conventional wisdom around EVs has long suggested fleets should avoid charging batteries to 100% whenever possible. But Geotab’s data showed little difference between vehicles regularly charged to full and those capped at 80%, provided the vehicles were being used consistently. “For vehicles that charged to 100%, but the vehicles were used every day or most days, there really wasn’t an observable difference between that and those who stopped it at 80%,” Argue said. The issue appeared when vehicles remained parked for long periods at high states of charge. “So our recommendation to fleet operators is use your vehicle, charge it to 100%, maybe don’t let that vehicle sit for a week on end at 100% state of charge,” she said. Fast Charging Showed a Clear Impact While daily charging habits produced fewer concerns than expected, Geotab did identify one factor that noticeably accelerated degradation: frequent use of high-power DC fast charging. Argue said vehicles using high-frequency, high-power fast charging showed average degradation rates of about 3.0% annually, compared to roughly 1.5% for vehicles relying primarily on slower charging