Is the battery on this used EV still good? Here's how to check.
The battery drives both the value and the range of a used electric car. On used cars listed through EVTrader, the seller-declared SoH is shown on the listing — so you know what you're buying.
In short: what is State of Health (SoH)?
State of Health shows how much of the original capacity a battery still has. Degradation is fastest in the early years, then slows down — after 5–8 years most cars still have ~85–90%. Above ~90% is good; below ~80% is worth a closer look. Manufacturer warranties typically cover 8 years or 100,000 miles down to ~70% capacity. Always have SoH verified independently before buying a used EV. Updated 2026-07-06.
What is State of Health (SoH)?
SoH is a percentage: 100% means the battery performs exactly as it did when new. It drops over time due to degradation. The good news: modern lithium-ion batteries degrade more slowly than many people assume.
The curve isn't linear. In the first year, SoH typically drops 2–4% (calibration and initial cycling). After that, the rate settles to roughly 1–2% per year. A 5-year-old electric car under normal use typically shows an SoH of 88–93%.
What accelerates degradation: very frequent rapid charging, prolonged exposure to extreme heat or cold, and leaving the battery at 100% or near 0% for long periods.
How to check battery condition
- OBD diagnostic: a diagnostic tool or OBD dongle reads SoH directly from the BMS. This is the most reliable method.
- Brand-specific readout: Tesla, Volkswagen and Hyundai show part of the SoH in the app or on-board screen. Useful, but less detailed than a full OBD reading.
- Dealer report: many dealers check the battery during servicing or part-exchange — ask for it explicitly before buying a used EV.
- EVTrader's SoH label: on used EVs listed through EVTrader, the seller-declared SoH is shown on the listing, together with its source (seller-declared today; independently verified is on our roadmap).
Battery warranty by brand
Most manufacturers guarantee at least 70% capacity after 8 years or 100,000 miles. If SoH drops below that threshold within the warranty period, you're entitled to a repair or replacement. Always check that the warranty is transferable to a second owner.
SoH and residual value
A lower SoH directly affects resale price. On the used-EV market, a car with SoH below 80% sells for roughly 6–12% less on average than a comparable car above 90%. Transparent SoH increases buyer confidence — and therefore price.
SoH also feeds into lease pricing: the healthier the battery, the lower the lessor's residual-value risk — which can mean a sharper monthly rate.
Understand residual valueGot a question about a used car's battery?
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Frequently asked questions about battery health (SoH)
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