What Your EV's Battery Warranty Actually Covers

“The battery is under warranty” is a comforting phrase that means less than most buyers assume. The actual coverage has a specific threshold, and knowing it changes how you should think about buying a used EV or planning to keep one long-term.

The federal floor

U.S. federal regulations require EV manufacturers to warrant the traction battery for a minimum of 8 years or 100,000 miles, whichever comes first. That’s the baseline every automaker selling in the US has to meet, though many offer more.

The number that actually matters: 70%

Coverage isn’t “the battery is warrantied against anything going wrong.” It’s specifically a capacity guarantee: automakers must warrant that a battery retains at least 70% of its original capacity through that 8-year/100,000-mile window. If your battery’s capacity drops below that 70% threshold inside the warranty period, the manufacturer is required to repair or replace it at no cost. Gradual degradation above that line, which is normal and expected for every lithium-ion battery, isn’t a warranty claim; it’s just how the technology works.

Some states require more

California has stricter requirements than the federal floor: vehicles certified to California’s PZEV standard get 10 years or 150,000 miles on the battery, and this extended requirement is now standard for 2026 model-year zero-emission vehicles sold in the state. If you’re in California, or buying a car that was originally sold there, check whether it carries the extended coverage before assuming only the federal minimum applies.

Why this matters more when buying used

An 8-year, 70%-capacity warranty sounds long until you translate it into what it means for a used purchase: a 5-year-old EV still has real warranty runway left, but a 7-or-8-year-old one is approaching or past the window entirely, meaning any capacity loss from that point forward is your risk, not the manufacturer’s. This is exactly why our best used EVs guide recommends the 3-to-4-year-old sweet spot: enough depreciation has already happened, but there’s still meaningful warranty coverage left.

What degrades faster than the warranty accounts for

The 70% threshold is a floor, not a prediction of what you’ll actually experience. Real-world degradation varies a lot by climate, charging habits, and specific battery chemistry, topics we cover in our guide to how EV batteries work. A battery sitting comfortably above 70% at year 6 tells you more about your specific car’s health than the warranty terms alone do.

Check this before you buy, not after

If you’re shopping used, ask for the specific battery health reading (most EVs can display this, or a dealer/independent inspector can pull it) rather than relying on age or mileage as a proxy. The warranty terms tell you the manufacturer’s worst-case commitment; they don’t tell you what condition the specific battery in front of you is actually in.

Sources

• Midtronics — What Warranty Does An EV Battery Cover
• Recharged — California EV Battery Warranty: 10-Year Rules & 2026 Changes
• Endurance Warranty — EV Battery Degradation And EV Warranties

Warranty terms vary by manufacturer and can exceed the federal minimum described here; always confirm the specific terms for the model and model year you’re considering.