Buying a used EV
Most of an electric car is simpler than the thing it replaced: no oil, no exhaust, no timing components, brakes that barely wear. Nearly all of the risk has consolidated into one component — so nearly all of the useful buying work is getting an honest, dated, comparable description of that component.
We are not going to print degradation percentages or range figures on this page. Any number we gave you would be an average of things that are not alike — different chemistries, thermal designs, climates and owners — and you would carry it into a negotiation about a specific car, where it would be worse than useless. What follows is the mechanism, and the method for getting the real numbers for the actual car.
What degradation actually is
Two things happen to a lithium-ion pack as it ages, and they are separate. Capacity fade means the pack holds less energy than when new, which is what people mean by "degradation" and what shows up as lost range. Resistance rise means the pack has become less willing to move energy quickly, which shows up as slower charging and sometimes reduced power — and it doesn't always track capacity fade.
What drives both: calendar time, which passes whether the car is driven or parked; heat, the most consistently damaging variable; time spent sitting at a very high state of charge; deep discharges; and high-rate DC fast charging, particularly on an already warm pack. The design of the car's thermal management matters too — a pack with active liquid cooling has a different exposure to a hot summer than one relying on air, which is a fair question to ask before you look at any individual example.
One more thing: degradation is usually faster early on and then flattens out. A young car with visible loss is not necessarily on a steeper trajectory than an older one that has settled — and nobody can extrapolate a straight line from two data points.
Three numbers people confuse
The EPA label range is a test-cycle figure produced for a new vehicle under defined conditions. It is a comparison tool between models, never a promise about your commute, and it has nothing to say about a six-year-old example of the same car.
The range estimate on the dashboard — the "guess-o-meter" — is a rolling prediction built from recent energy consumption. Drive gently for a week and it rises; tow something up a hill and it collapses. It forecasts your driving, not your battery, and reading battery health from it is the most common mistake buyers make.
The state of health is the number you want: the vehicle's own estimate of present usable capacity against its original capacity. Still an estimate, computed by software — but the only one of the three trying to describe the pack.
Reading a state-of-health readout
On some cars it's in a service or battery menu on the car's own screen; on others it takes an OBD-II adapter and an app that understands that model. A franchise service department can usually run a proper check and print it.
A calculated estimate, not a direct measurement. The battery management system infers capacity from charge and discharge behavior over time and refines it when the car sees wide swings in state of charge. A pack cycled only in a narrow band may carry a stale figure.
Different tools compute health differently, so two readouts on the same car can disagree without either being wrong. Compare like with like: same tool, same method, always with a date. A screenshot with no date and no source is not evidence.
Do not rely on one figure. Check it against the car's reported usable energy, against what an actual drive consumed for the distance covered, and against how the charging rate behaves. A health figure that looks fine alongside a charge rate that tapers unusually early is telling you something.
A prediction. Nothing measurable today establishes how much life remains, because the trajectory depends on how the next owner charges, parks and drives. Nor is it a warranty determination — coverage is decided by the manufacturer under its own criteria.
What to ask for
These are the requests, roughly in order of how much they settle. What you are trying to avoid is a conversation conducted entirely in reassurances.
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A dated battery health report, run while you watch
Not a screenshot from last spring. Ask that it be produced during the viewing, from the car's own menu or by a dealer, with the date and source on it.
Can we pull the battery health readout together today, and can I have it in writing with the date on it?
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The charging pattern
Daily charging habits do more to a pack over years than mileage does. Some vehicles and apps record fast-charging sessions; where that data exists, ask to see it rather than hear about it.
What did you set the daily charge limit to? Did you leave it plugged in at full? How often did you use fast chargers, and does the car show a count?
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Where it lived
Garaged or on the street, and in what climate. A car that spent its life in sustained heat has had a harder time than the odometer suggests, and plenty of used cars here arrived from somewhere hotter.
Was it garaged? Has it always been in this region?
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High-voltage service history
Any module or pack replacement, any work on the cooling loop, any high-voltage fault codes. A replaced pack may be the best thing about the car — but it changes the age of what you're buying.
Has the pack or any module ever been serviced or replaced? Can I see the repair order?
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Remaining coverage, verified by VIN
High-voltage components are typically covered separately from the rest of the vehicle, on terms that differ by manufacturer and model year. Do not accept anyone's summary — including ours. Call a franchise service department with the VIN and ask what remains and whether it transfers.
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Software, accounts and hardware
Confirm the car is on current software and can still receive updates, that the previous owner's account and phone keys have been removed, that connected services transfer, and that the charging equipment — mobile connector, adapters — is actually present. Adapters are frequently missing and not cheap to replace.
The parts that have nothing to do with the battery
Tires. Electric cars are heavy and deliver torque instantly, and both consume tires faster than an equivalent gasoline car. Check the load rating on what's fitted, and read the wear — the tread tells you how it was driven.
Brakes. Regenerative braking does most of the slowing, so pads last unusually well. The flip side is that rarely used discs corrode, especially through a salted New Jersey winter, so a used EV sometimes needs brake work for rust rather than wear. Look at the rotor faces and edges.
The 12-volt battery. Electric cars still have one, it runs the computers and the contactors, and when it dies the car strands itself in ways that look far more alarming than the cause. Ask when it was last replaced and have it tested.
The charge port. Inspect the pins and latch for damage and corrosion, and test that the car takes a charge — on AC and, if you can arrange it, on DC. Watch the rate it accepts and whether it holds it, after a drive when the pack is warm: cold packs charge slowly by design, and you don't want to read normal behavior as a fault.
And the New Jersey part
Cold weather reduces usable range — batteries deliver less when cold and cabin heating draws real energy — by an amount that depends on the car's heating design and on your commute. It is temporary. But if your winter drive already sits near the edge of what a used pack will do, plan around the car that exists in February, not the one you're test-driving in September.
How we handle it here. Any electric car on our lot is listed with a dated state-of-health readout, the tool named, and the 12-volt battery load-tested — inside the published 168-point inspection. Where the car can't produce a health figure we say so rather than substitute an estimate, and we tell you what charging equipment is in the trunk.
General information for used car buyers, not a diagnostic procedure and not a substitute for inspection by a qualified technician. High voltage systems are dangerous and should only be serviced by trained personnel. This page states no range, capacity, degradation figure or warranty term; those vary and must be confirmed for the specific VIN.
Related reading
- Hybrid battery health Assessing a traction pack without specialist tools, and the limits of every observation.
- Reading a tire The sidewall decoded, and what a wear pattern says about the car rather than the tire.
- What the history report misses The things that never make it into a report, and why the paperwork trail has holes in it.