EV battery health, degradation & warranty by brand

Lithium-ion batteries gradually lose usable capacity with time and charge cycles; heat and frequent fast charging to 100% can add wear. The car's battery management system protects the pack, and most of the capacity loss shows up as a lower range at 100% charge.

Where to get a battery health report

• Recurrent (third party) — Independent company offering real-world EV data, including battery insights based on temperature, age and charging patterns, to help shoppers, owners and dealers buy, sell and understand EVs. source
• Manufacturer dealer battery capacity check (warranty claim) — Battery-capacity warranty claims are judged by the automaker's own service measurement. Example: Ford's 2025 BEV warranty guide says an authorized EV Certified Ford Dealer determines whether capacity is below 70% of beginning-of-life capacity, using a method at Ford's sole discretion. source
• UN GTR No. 22 / EPA battery state-of-health monitor (removed in U.S.) — EPA had adopted an on-board battery state-of-health (State of Certified Energy) monitor requirement based on UN Global Technical Regulation No. 22 (In-vehicle Battery Durability for Electrified Vehicles, adopted April 14, 2022). EPA removed that requirement (40 CFR 86.1815-27) in its February 2026 final rule, so U.S. federal law no longer mandates an in-car battery health readout. source
• California ACC II battery state-of-health requirement — California's ACC II battery warranty (13 CCR 1962.8) is defined by battery state of health as described in 13 CCR 1962.5(c)(4)(A)4.c. and d. (70% for MY2026-2030; 75% for MY2031+). Its enforceability is contested after the 2025 CRA resolutions. source

What to ask the dealer

• Can you provide a battery state-of-health report (percent of original capacity)?
• What range does the car show at a 100% charge, and in what conditions?
• What is the original in-service date, and how much battery warranty remains?
• Has the battery or any module been replaced, and are all recalls done?
• Which charging cable and adapters come with the car?

• Battery state of health — ask for a battery health (SOH) report from the dealer or the brand's service department; note the range the car shows at 100% charge.
• Battery warranty remaining — from the original in-service date and current odometer; confirm it transfers to you (by brand).
• Recalls — check the VIN at NHTSA recalls; battery and charging-system recalls must be repaired for free.
• Charging port and connector — J1772/CCS, NACS or CHAdeMO; which adapters come with the car; does it charge on both Level 2 and DC fast (test both if you can).
• Charging cable — is the portable cordset included?
• Range for your life — your longest regular trip, winter range, and where you'll charge (home, work, public).
• Home charging — 120 V outlet or a 240 V Level 2 installation; check your utility's EV rate and charger rebates (utility programs).
• Tires and brakes — EV-rated tires; brake condition (regenerative braking reduces wear, but rotors can corrode from little use).
• Software and connected services — what features and subscriptions transfer to a new owner.
• Vehicle history — CARFAX/AutoCheck when the dealer provides it (look for the CARFAX link on AutosXchange listings), accident and flood history.
• Fees — your state's EV registration fee (by state).

No federal law sets a battery capacity-retention warranty for EVs. The federal requirement is an emissions-warranty rule. In March 2024 EPA designated high-voltage batteries and associated electric powertrain components of light- and medium-duty BEVs and PHEVs as 'specified major emission control components' under Clean Air Act section 207(i)(2), with a warranty period of 8 years or 80,000 miles, whichever occurs first, for model year 2027 and later (DOE AFDC summary). The regulatory text (40 CFR 85.2103(d)(1)(v)) makes the battery coverage optional before MY2027 for light-duty vehicles at or below 6,000 lb GVWR, and for heavier vehicles until they are first certified to Tier 4 NMOG+NOx bin standards, no later than MY2031. EPA's February 2026 final rule rescinding the GHG endangerment finding (published Feb 18, 2026) kept that battery paragraph in revised form. It removed 40 CFR 86.1815-27, the battery durability and state-of-health monitor rule (80% of certified usable battery energy at 5 years/62,000 miles; 70% at 8 years/100,000 miles), and removed 85.2103(d)(3), the warranty claim tied to that monitor. California's ACC II rule (13 CCR 1962.8, MY2026+ ZEVs and PHEVs certified for California) requires automakers to warrant to the original and each subsequent purchaser that the battery's state of health won't fall below 70% for 8 years/100,000 miles (MY2026-2030), rising to 75% for MY2031+. EPA states that Congressional Review Act resolutions enacted June 10, 2025 (Pub. L. 119-15, 119-16, 119-17) left its ACC II waiver with no force and effect. California's Air Resources Board disputes this, so whether the California battery warranty can be enforced is contested.

What does an EV battery warranty cover?

The manufacturer's battery (traction battery) warranty covers defects and, for many brands, capacity loss below a stated percentage within a period such as 8 years or 100,000 miles. Terms vary by brand, model year and state; the warranty booklet is the authority.

How do I check the battery health of a used EV?

Ask the dealer for a battery state-of-health (SOH) report from the manufacturer's service department or a battery-diagnostic provider, compare the range displayed at a 100% charge with the original EPA range, and check NHTSA for battery-related recalls.

Does the EV battery warranty transfer to the next owner?

Usually the remaining manufacturer battery warranty stays with the vehicle, but confirm in the brand's warranty terms (listed in the table on this page where officially published).