7 min read · Last updated August 28, 2026
- Federal law only guarantees an electric vehicle (EV) 8 years or 80,000 miles against battery defects. The “70 percent at 100,000 miles” figure most sites cite is California’s rule, not federal, and disputed since mid-2025.
- Manufacturer capacity thresholds vary: Nissan covers below 75 percent at 96 months or 100,000 miles, Kia below 70 percent at 10 years or 100,000 miles, and General Motors (GM)/Chevrolet publishes no percentage at all.
- A 22,700-vehicle fleet study found average degradation of 2.3 percent a year, and independent Tesla Model 3 tracking found comparably modest losses, both well inside most warranty thresholds.
- On a used EV worth $17,000 at 68 percent state of health, replacing a $10,500 battery nets about $6,500, while selling as-is nets roughly $11,560, a $5,060 gap that state of health decides and dashboard range never would.
In this article
- The dashboard number and your battery’s real health are not the same measurement
- What the federal warranty actually promises, and what it doesn’t
- What real batteries actually do over 5, 8, and 10 years
- The keep-or-sell math
- What a seller doesn’t have to disclose, and what a smart one does anyway
- Frequently asked questions
Terrence’s Nissan LEAF has 71,400 miles, and its dashboard range will not sit still. A cold morning “full charge” reads 118 miles; a warm afternoon, same 100 percent charge, reads 142. He assumed the swing meant his battery was failing. It isn’t. The number that decides whether Nissan owes him a replacement, and what a buyer would pay tomorrow, is a different measurement called state of health (SOH), and it hasn’t moved anywhere near that much in months.
The dashboard number and your battery’s real health are not the same measurement
A dashboard range estimate recalculates from your last several miles: how fast you went, whether the climate control ran. Cold weather alone can knock a real chunk off that number overnight with the battery’s health unaffected. The Union of Concerned Scientists, a nonprofit science research group, defines state of health as “a measurement that indicates the level of degradation and remaining capacity of the battery… typically represented as a percentage of its initial capacity.” Range is a forecast about today’s drive. SOH is a fixed condition report, checked through the vehicle’s diagnostics or a phone app, moving slowly over months, not overnight.
What the federal warranty actually promises, and what it doesn’t
Every EV sold in the U.S. carries a federal battery warranty of at least 8 years or 80,000 miles under the Clean Air Act, enforced by the Environmental Protection Agency (EPA). That federal floor covers defects, not a specific capacity loss. The EPA’s own 2024 rule states it “is not tying the battery warranty failure criterion to the durability performance requirement,” leaving the percentage up to each manufacturer. What most people mean by “70 percent at 8 years, 100,000 miles” is California’s own rule, not a federal one, and as of mid-2025 its legal footing is disputed after Congress voted to revoke the EPA waiver behind it. Know your manufacturer’s number instead of assuming a floor that may not exist.
| Manufacturer | Warranty length | Capacity threshold |
|---|---|---|
| Nissan (LEAF) | 96 months or 100,000 miles | Below 9 of 12 capacity bars, about 75 percent |
| Kia | 10 years or 100,000 miles | Below 70 percent of original capacity |
| GM / Chevrolet | 8 years or 100,000 miles | No published percentage; handled as a defect or recall replacement |
| California’s own rule (contested) | 8 years or 100,000 miles | Below 70 percent for 2026-2030 models; legal status disputed since mid-2025 |
Nissan’s own LEAF warranty booklet, Kia’s warranty page, and General Motors’ filed service bulletin confirm the figures above.
What real batteries actually do over 5, 8, and 10 years
The numbers in warranty tables are floors, not forecasts, and real-world data suggests most EV batteries clear them comfortably. Geotab, a fleet telematics company, analyzed more than 22,700 electric vehicles and found average degradation of about 2.3 percent a year, projecting roughly 81.6 percent of original capacity after eight years, well above most replacement thresholds. Recurrent Auto’s tracking of real Tesla Model 3s found similarly modest losses: about 95 percent of original range at three years, 93 percent at five, with the fastest losses concentrated in a car’s first 50,000 miles. A battery that fails early enough to trigger a claim is the exception, not the rule.
The keep-or-sell math
This site’s own repair-it-or-sell-it break-even math for gas engines asks one question: does the fix return more value than it costs, for as long as you keep the car. The same question applies to a degraded battery, with state of health replacing engine age. Say a used EV worth $17,000 has a state of health of 68 percent, and a full pack replacement runs $10,500, near the middle of Recurrent Auto’s $5,000-to-$16,000 range for real replacements. Replacing the pack nets around $6,500 ($17,000 minus $10,500). Selling as-is at a similar discount, roughly $11,560, beats that by just over $5,000. The math only flips when the pack cost is lower, the ownership period is long, or the replacement genuinely restores more value than it costs, the same conditions that decide a gas-engine repair-or-sell call here.
What a seller doesn’t have to disclose, and what a smart one does anyway
No state or federal law requires a private seller to disclose a battery’s state of health, the same gap covered here for an open recall. But the market is moving past “not legally required” on its own. CarMax now publishes a battery range score on every EV in its inventory through a partnership with Recurrent, letting a shopper check the car’s actual measured range before making an offer. A seller who knows the health is degraded and still represents normal range carries the same misrepresentation risk already covered here for an unmentioned recall. Running the numbers first protects you either way.
Frequently asked questions
What is battery state of health, and how is it different from my dashboard’s range estimate?
State of health (SOH) measures how much of a battery’s original usable capacity remains, as a percentage. Your dashboard’s range recalculates from recent driving, weather, and climate control, so it swings daily even though SOH itself moves slowly, over months and years.
How long is an EV battery actually warrantied for?
Federal law requires at least 8 years or 80,000 miles against battery defects, enforced by the Environmental Protection Agency. That floor sets no specific capacity percentage. Manufacturers set their own thresholds, and they vary meaningfully, so check your own automaker’s warranty language.
What percentage of capacity loss actually triggers a warranty replacement?
It depends on the manufacturer. Nissan’s LEAF covers capacity loss below roughly 75 percent for 96 months or 100,000 miles. Kia covers below 70 percent for 10 years or 100,000 miles. GM and Chevrolet publish no capacity percentage at all.
How much does an EV battery actually degrade over time?
Real-world data is reassuring. A 22,700-vehicle fleet study found average degradation around 2.3 percent a year, and independent Tesla Model 3 tracking found about 95 percent of original range retained after three years. Most batteries degrade slowly, clearing their warranty threshold.
Do I have to disclose my EV’s battery health when I sell it privately?
No state or federal law requires it. Major dealer chains now publish battery range scores voluntarily anyway, and a seller who knowingly misrepresents a degraded battery as having normal range carries the same misrepresentation risk covered elsewhere here for an undisclosed open recall.
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