How far does capacity have to fall before the warranty does anything?

It depends on the booklet, not on any single industry standard. Hyundai's 2026 owner's handbook works to 70 percent of original battery capacity over 10 years or 100,000 miles. Chevrolet's 2025 electric vehicle warranty manual replaces or repairs the pack if capacity falls below 75 percent of its original value within 8 years or 100,000 miles. Nissan's 2025 LEAF booklet does not use a percentage at all, covering capacity loss below nine segments on the car's twelve-segment gauge for 96 months or 100,000 miles. Read your own model-year document; a threshold quoted from a forum is a threshold for somebody else's car.

Does the battery warranty transfer to me if I buy the car used?

Usually yes, but check the transfer clause rather than assuming. Chevrolet's EV manual states the warranty is provided to the original owner and any subsequent owners. Nissan's booklet transfers automatically with no action required, with a narrow exception in the first six months tied to registration outside the United States. Hyundai's handbook names which coverages transfer, and its powertrain warranty is explicitly original-owner-only. Either way the clock starts at the car's original in-service date, not at your purchase date.

Can charging habits void an EV battery warranty?

Ordinary fast charging is not misuse, but federal regulation does open a door. Under 40 CFR 85.2104(f) a manufacturer's written instructions may identify behaviours expected to unreasonably or artificially shorten battery durability, with exceeding towing capacity given as the example, and evidence of proper use under that paragraph is generally limited to onboard data logging plus, if the manufacturer asks, a statement from the owner. The same paragraph says a manufacturer should not treat a behavior as improper use if the vehicle can be designed to prevent it.

Do I get a brand-new pack if the claim succeeds?

Rarely. Nissan's booklet says a capacity repair may not return the battery to an as-new condition with all twelve segments, only to nine or more. Hyundai's says a repair or replacement will maintain at least equal capacity to the battery before the failure, but no less than 70 percent of original. Chevrolet's says the pack will be replaced with a battery appropriate for the age and mileage of the vehicle. A successful claim buys the threshold back, not a new car.

EV Battery Warranty: Reading the 70 Percent Threshold

"Eight years, 100,000 miles, 70 percent" gets repeated as if it were one rule covering every electric car sold in the United States. Put three current booklets side by side — Hyundai's 2026 handbook, Chevrolet's 2025 EV warranty manual, Nissan's 2025 LEAF booklet — and no two of them say the same thing.

One works to 70 percent. One works to 75. One never mentions a percentage at all and counts bars on a gauge instead. And the federal regulation usually named as the source of the eight-year rule says eight years and 80,000 miles, with no capacity figure anywhere in it.

If you are here because an app showed you a number you did not like, the app is not the document that decides anything. Your booklet is.

Three booklets, three thresholds

Hyundai, 2026 owner's handbook. The high-voltage battery and a listed set of direct-energy components — battery management system, power relay assembly, traction motor, on-board charger and the rest — are covered for 10 years from original retail delivery or date of first use, or 100,000 miles. On capacity the booklet says loss over time is "covered not to degrade more than 70% of the original battery capacity," and the repair clause promises a fix that maintains at least the capacity the pack had before the failure "but no less than 70% of the original battery capacity" (2026 Owner's Handbook and Warranty Information, PDF, read 22 August 2026).

Chevrolet, 2025 electric vehicle warranty manual. Propulsion battery pack and internal components for 8 years or 100,000 miles, and the capacity clause is the plainest of the three: the battery "will be replaced/repaired if the capacity falls below 75% of its original value during the warranty period, as determined by a certified dealer, with a battery appropriate for the age and mileage of the vehicle" (Chevrolet Electric Vehicle Limited Warranty and Owner Assistance Information, PDF, read 22 August 2026). Five points stricter than the figure the internet treats as universal.

Nissan, 2025 LEAF warranty booklet. Defect coverage on the lithium-ion battery for 96 months or 100,000 miles, then a separate capacity coverage for the same term — "against capacity loss below nine segments as shown on the vehicle's battery capacity level gauge" (2025 LEAF warranty booklet, PDF, read 22 August 2026). The obvious arithmetic — nine of twelve, so 75 percent, the same as Chevrolet — is not something the document supports. Nowhere does it say what share of capacity one segment stands for; how the gauge behaves is a matter for the owner's manual of that model year, not the warranty. On a LEAF the gauge is the instrument of record and your phone app is not.

Tesla's, Ford's and Rivian's current booklets could not be retrieved for direct quotation while this page was written, so no figure for those three appears here. An owner portal or a dealer will hand you one. Better a gap than a number taken second-hand.

The federal floor is real, and it is not what you were told

Here is the sentence that circulates everywhere: federal law requires an eight-year, 100,000-mile battery warranty. The regulation says something narrower.

The emission defect warranty at 40 CFR 85.2103 runs two years or 24,000 miles for light-duty vehicles generally, with a list of "specified major emission control components" carrying eight years or 80,000 miles. Paragraph (d)(1)(v) puts traction batteries on that list: "Batteries serving as a Renewable Energy Storage System for electric vehicles and plug-in hybrid electric vehicles, along with all components needed to charge the system, store energy, and transmit power to move the vehicle." Read 22 August 2026; the section carries amendments through 91 FR 7759, 18 February 2026.

Two things about it are easy to miss. That subparagraph is optional before model year 2027 for light-duty vehicles and light-duty trucks at or below 6,000 pounds GVWR, and optional for vehicles above 6,000 pounds until they are first certified to Tier 4 NMOG+NOX bin standards under 40 CFR 86.1811-27(b), no later than model year 2031. And what the section warrants is emissions — performance against the standards in paragraph (c), defects in paragraph (d). Search the whole of it for a capacity percentage and there is none. Federal law is not the reason your booklet promises 70 percent.

Where 8 years, 100,000 miles and 70 percent actually come from

California. Title 13 of the California Code of Regulations, section 1962.8, adopted out of the Advanced Clean Cars II rulemaking, sets warranty requirements for 2026 and later model year zero-emission vehicles certified for sale in the state. Subsection (c)(3) is the operative one, and its structure matters more than its number: the manufacturer must warrant that the battery is "free from defects in materials and workmanship which cause the battery state of health ... to deteriorate to less than 70% for a warranty period of eight years or 100,000 miles, whichever first occurs, for 2026 through 2030 model years, and 75% ... for 2031 and subsequent model years" (final regulation order, section 1962.8, PDF, read 22 August 2026).

Notice what carries the weight. It is not a bare guarantee that your pack will hold 70 percent. It is a promise that defects in materials and workmanship will not drive it below 70 percent, which is a different sentence and a harder one to win on. The state of health being measured is the parameter defined back in section 1962.5 — the same one your 2026-or-later dashboard is supposed to display. That link between the screen and the claim is the genuinely new thing here, and what the display rule requires, along with the federal waiver fight hanging over it, is its own story.

The same section covers the hardware around the pack on much shorter terms: propulsion-related parts for 3 years or 50,000 miles, and 7 years or 70,000 miles for parts the manufacturer designates as "high-priced." An inverter is not the battery, and does not get the battery's clock.

Whether it survives the sale

Two clocks, and only one of them is yours.

The warranty period under 1962.8 begins on the date the vehicle was delivered to its ultimate purchaser, or for a demonstrator, when it was first placed in service. The federal rule at 85.2103(b) says the same. A three-year-old used EV therefore comes with five years of an eight-year term, not eight, and that in-service date is the figure to get in writing before you sign anything.

On transfer, the regulation is blunter than some booklets: 1962.8(c)(1) and (c)(3) require the manufacturer to warrant "to the ultimate purchaser and each subsequent purchaser." The manufacturers mostly follow. Chevrolet's manual says the warranty "is provided to the original owner and any subsequent owners of the vehicle during the warranty period." Nissan's transfers "without any action on your part," with one narrow trap: it is void rather than transferable if, within the first six months after delivery to the original owner, ownership changes and the car is registered outside the United States.

Hyundai's handbook is where a used buyer should slow down. Its transferability paragraph names six coverages that pass to subsequent owners — new vehicle limited, anti-perforation, federal emission performance, federal emission design and defect, California emission control systems, replacement parts and accessories — and the hybrid, plug-in hybrid and electric vehicle section is not among the names. The summary chart on page 16 shows that coverage at 10 years/100,000 miles carrying none of the original-owner footnote that sits on the powertrain row, where the drop to 5 years/60,000 miles for subsequent owners is spelled out. Those two readings do not obviously agree. If you are buying a used Hyundai or Kia EV on the strength of remaining battery coverage, get the answer against your VIN, in writing, from the manufacturer, and not from this page.

What actually voids it, and what cannot

The folklore here is worse than usual, so take it from the text.

Under 40 CFR 85.2104 a manufacturer may write instructions identifying behaviors "expected to unreasonably or artificially shorten battery durability," and gives exceeding towing capacity as its example — one more reason to know what a trailer does to your margins before the trip. The same paragraph adds a limit that rarely gets quoted: a manufacturer "should not consider actions to be improper use if the vehicle can be designed to prevent the targeted behaviors or operating modes." Evidence of proper use under that paragraph is "generally limited to onboard data logging," though a manufacturer may also ask the owner for a statement about specific behaviors. Your car is the witness, and it testifies for both sides.

Paragraph (h) then lists what can never be the basis for a denial, including the use of an uncertified part that is irrelevant to the failure, and any cause attributable to the manufacturer. Section 85.2105 makes a manufacturer denying a performance warranty claim over an uncertified part put the causal connection in writing, list the evidence it relied on, and hand that evidence over on request.

California runs the same direction. Coverage drops out only if the manufacturer demonstrates that the vehicle was abused, neglected or improperly maintained and that this was the direct cause of the failure — 1962.8(c)(7). Subsection (c)(4)(J) says the owner may use any replacement part in maintenance or repairs without reducing the manufacturer's obligations, and (c)(4)(K) says a CARB-exempted add-on part cannot, by its presence alone, be grounds to disallow a claim.

Booklet exclusions are narrower than rumor too. Hyundai's list is collision or accident, intentional abuse including ignoring active vehicle warnings, servicing or opening the battery by unauthorized personnel, physical or programming attempts to extend or reduce battery life, direct flame, and flooding. Chevrolet goes the other way and grants permission in writing: normal use of the pack for backup power during outages, for reasonably selling energy back to the grid, and for reasonable use as a mobile power source is covered. Two answers to the same vehicle-to-home question, in two booklets.

What appears on nobody's exclusion list: cold weather. A range figure that collapses in January and recovers in April is climate load rather than capacity loss, and a claim built on it will not survive the first diagnostic.

What a successful claim actually gets you

Less than most people picture, and it is written down.

Nissan: a capacity repair "may not return your lithium-ion battery to an 'as new' condition with all 12 battery capacity segments, but it will provide the vehicle with a capacity level of nine segments or more." Hyundai: at least equal capacity to before the failure, no less than 70 percent of original. Chevrolet: a battery "appropriate for the age and mileage of the vehicle." Remanufactured and refurbished packs are permitted by all three booklets, and 1962.8(c)(4)(I) permits them in the regulation, with "performance appropriate for the age and mileage."

Three procedural details are worth knowing before you book, all from 1962.8(c)(4). You cannot be charged for diagnostic labor that leads to a finding that the part is defective, provided the work is done at a warranty station. Repairs are due at no charge across the manufacturer's authorized service network, not only at the dealer who sold the car. And a repair left incomplete beyond 30 days from when you first presented the vehicle triggers an exception that opens the door to having the work done elsewhere.

I am not a lawyer or a service manager, and none of this is advice about your claim. It is what the documents say, each linked so you can hold the wording against your own copy.

Twenty minutes with your own booklet

Find the document for your exact model year: glovebox, owner portal, or a search for the model year plus "warranty booklet pdf" restricted to the manufacturer's own domain. Then search the PDF for four strings — capacity, transfer, excluded, state of health.

Write down five things while it is open. The capacity threshold and how it is expressed. The term in years and miles. The in-service date it runs from. Whether your state follows the California rules. And the one exclusion that would be hardest for you to disprove.

Then keep the file somewhere you will find it in six years, next to your state-of-health log. The claim that matters will be argued from those two documents. Not from a screenshot of a percentage.