Degradation is normal, not a defect
Like the battery in a phone or laptop, an EV or hybrid battery gradually loses some of its original capacity to hold a charge over time and use. This is expected, gradual chemical aging — not a sign that anything has gone wrong — though a battery that degrades unusually fast could indicate an actual issue worth having checked.
In practice, this shows up as a slow decline in the vehicle's real-world range compared to when it was new.
What generally influences the rate
- Charging habits — for many battery types, frequently charging to 100% or letting the battery sit very low for extended periods is generally understood to accelerate wear more than keeping the charge in a more moderate range day-to-day. Some chemistries (such as LFP) are designed to be charged to 100% regularly, though — so follow your manufacturer's own charging recommendation rather than a general rule.
- Fast charging frequency — relying heavily on DC fast charging rather than slower Level 1 or Level 2 charging is generally associated with somewhat faster degradation, though modern battery management systems are designed to mitigate this.
- Heat exposure — consistently high temperatures, including from frequent fast charging or hot climates, tend to accelerate battery aging.
- Total mileage and age — more charge cycles and more time in service both contribute, simply from cumulative use.
Why exact numbers aren't provided here
Real-world degradation rates vary significantly by battery chemistry, thermal management design, climate, and how a specific vehicle is used and charged — there's no single reliable percentage-per-year figure that applies across vehicles, which is why this guide doesn't cite one. Manufacturer battery warranties (see our guide to how those work) are the concrete backstop: many guarantee the battery won't fall below a specified capacity within a set time and mileage window.
If you're buying a used EV or hybrid
A battery health check — either from the dealer, an independent EV specialist, or diagnostic tools some manufacturers support — is worth treating as part of the pre-purchase inspection, the same way you'd check any other major component before buying.
Free. See its recalls, factory coverage and a Protection Check — no phone number needed.