Warranty law
The rule you
think exists
No federal law guarantees eight years or 100,000 miles on the battery of a used electric car. That figure is the manufacturer's own contract, offered voluntarily.
At a glance
- The statute says 80,000 miles, not 100,000, and it named only three components, none of which was the battery
- The battery was added for model year 2027, so every used electric car on sale today predates it
- The 70 percent figure comes from a certification regulation, not from a warranty booklet
- California does not require ten years on every electric car battery, and the reason is stranger than it sounds
What the statute actually says
Eighty thousand miles, not one hundred thousand. The statute names only three specified major emission control components, and they are a catalytic converter, an electronic emissions control unit and an onboard emissions diagnostic device. The traction battery was not one of them.
The period is eight years or 80,000 miles. It runs to the ultimate purchaser and each subsequent purchaser, so where it applies it does transfer with the car.
When the battery was added
EPA designated the high voltage battery and associated electric powertrain components as specified major emission control components, which pulls them into the eight year and 80,000 mile warranty.
Every used electric car being sold right now predates this. It does not apply to them.
Where the 70 percent figure comes from
Minimum state of certified energy of 80 percent at five years or 100,000 km, and 70 percent at eight years or 160,000 km.
This is a certification requirement placed on the manufacturer, not a promise made to the buyer. The widely quoted 70 percent threshold traces back here and to the California regulation below, which is why some of the percentages attributed to individual carmakers may be regulatory numbers retrofitted onto warranty booklets that never stated a figure.
California, and the used market
For model years 2018 to 2025, which is essentially the whole used market, the regulation sets 15 years or 150,000 miles for the emissions warranty generally, except 10 years for a zero emission energy storage device used for traction power. It contains no capacity retention floor at all.
The traction battery provision sits in the plug in hybrid subsection and reaches BEVx vehicles separately. On that reading a pure battery electric car sold new in California gets no state mandated traction battery warranty at all, only the manufacturer's own.
California from 2026, if it survives
The newer regulation requires eight years or 100,000 miles, whichever first occurs, with a floor of 70 percent state of health for 2026 to 2030 and 75 percent from 2031. It covers battery electric cars fully, and it transfers to each subsequent purchaser.
What each carmaker actually wrote
The law is one thing. What a manufacturer put in its own warranty booklet is another, and several wrote no capacity percentage at all. The five that could be checked, and the seven that could not.
Questions people actually ask
Does the battery warranty transfer to me as the second owner
Is 70 percent the level at which they replace the battery
Buying a Used EV or Hybrid?
Get the battery measured before you pay for it. A PPI Auto inspector tests the pack on the car you are looking at and sends you the numbers. Starting at $225.