How much does an electric car battery actually degrade?
Considerably less than early fears suggested. Large fleet datasets now indicate average degradation of roughly 1–2% of capacity per year, slowing after the first year, with most packs retaining around 85–90% after eight to ten years.
The shape of the curve. Loss is front-loaded: a noticeable drop in the first few months as the cells settle, then a long slow decline. A car showing 5% loss in year one is not on track to lose 5% every year.
What actually drives degradation:
Calendar ageing, which happens regardless of use, and is worsened by sitting at a high state of charge in heat. A pack left at 100% in a hot climate degrades fastest — this matters more than most drivers realise.
Cycle ageing, from charging and discharging. Deep cycles from very full to very empty stress cells more than partial ones.
Heat, which is the single largest factor. Cars with liquid-cooled packs degrade markedly more slowly than the early air-cooled designs that produced the technology's poor reputation.
Frequent DC rapid charging, which has a measurable but smaller effect than once assumed, particularly in well-cooled packs.
Chemistry. LFP cells tolerate full charging and many more cycles; NMC packs are more energy-dense and prefer partial charging.
What does not cause it: ordinary driving, regenerative braking, or home AC charging overnight.
What you can do: keep the daily range roughly between 20% and 80% for nickel-based chemistries; avoid leaving the car full in heat, especially parked for weeks; use rapid charging when useful rather than routinely; and plug in during extreme cold so the pack can condition itself.
Warranties typically cover eight years or a set mileage with a guaranteed remaining capacity, commonly 70%. Claims are relatively rare.
Batteries rarely fail outright. Individual module faults are repairable, and packs below automotive standard retain real value in second-life storage before recycling — which is why residual value expectations have improved.
Check the state of health when buying used, either through the car's own menu or a diagnostic scan.