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How do I check the battery health of a used electric car?

There is no official test, and that is the first thing to understand. No UK law requires a battery health certificate for a used electric car, and we have found no UK rule that defines what one would have to contain. The MOT does inspect the battery — it is a mandatory item on electric and hybrid cars — but the inspection manual says a propulsion battery is to be assessed visually only, and the only defects listed are that it is insecure or leaking. State of health, capacity and degradation are not measured at any point. So a car can pass its MOT with a badly degraded battery and nothing on the certificate will say so. What you can do instead is check the remaining manufacturer battery warranty, read the car’s own state-of-health figure, pay for an independent diagnostic test, and watch how it behaves on a rapid charger.

What the MOT actually does to the battery

Both common claims about this are wrong. The MOT does not ignore the battery, and it does not test its health. Section 4.13 Battery(ies) of the inspection manual says: “You must inspect the battery(ies) on all vehicles including electric and hybrid vehicles.” Then it says how: “The propulsion batteries are unlikely to be accessible, but if they are they should be assessed visually only.”

That leaves exactly three things that can be recorded against it:

DefectCategory
A battery insecure but not likely to fall from carrierMinor
A battery insecure and likely to fall from carrier or cause a short circuitMajor
A battery leakingMajor

Capacity, range and state of health appear nowhere in that section. A car whose battery has degraded badly passes this item outright, provided the battery is secure and not leaking. Worth knowing too that a Minor defect is still a pass — what an MOT advisory means explains the grades.

Source: DVSA MOT inspection manual for private passenger and light commercial vehicles, section 4.13 Battery(ies). Read 2026-09-19. This manual governs the test in Great Britain; Northern Ireland’s vehicle test is run by the DVA under its own rules.

There is no legal requirement for a battery health certificate

No UK law requires one. We have found no government body that issues one, and no UK rule setting out what one would have to measure or how it should be expressed. Private companies sell battery health reports and some dealers supply them, which is genuinely useful information — but it is a commercial product, not a regulated document, and two reports on the same car can measure different things and present them differently.

Treat claims about what certification is worth with the same care. Figures circulating about certified electric cars selling for hundreds of pounds more, and days faster, trace back to a press release from a company that sells battery health certificates. That may well be true; it is not independent evidence, and we are not going to repeat a vendor’s own marketing as a market fact.

Four things that do tell you something

The remaining battery warranty. Most manufacturers give the battery a separate, longer warranty than the car, promising it will not fall below a stated share of its original capacity within a set number of years and miles. On a used car what matters is how much of that is left, and whether it transferred to you. The thresholds and mileage caps vary and some manufacturers state them inconsistently across their own pages, so confirm the terms for the exact car with the manufacturer — our warranty by make guide covers what transfers on a used car generally.

The car’s own state-of-health figure. Many electric cars will show one in a service or diagnostic menu, and an OBD reader with model-specific software will usually retrieve it. It is the manufacturer’s own calculation rather than a standard measurement, it moves with temperature and recent use, and it is not strictly comparable between makes — so read it as a strong indicator rather than a verdict.

An independent diagnostic test. Several specialists will test a specific car and give you a report. Ask what the test actually measures before you pay for it.

How it charges. On a rapid charger a healthy battery accepts a high rate at a low state of charge and tapers as it fills. One that never reaches a decent rate, or tapers very early, is worth asking about. And since where you charge dominates what an electric car costs to run, it is worth establishing anyway.

How much it should weigh on the decision

Less than most buyers expect, and much less than charging access. Degradation costs you range in proportion — a tenth less capacity is a tenth less range, which is nothing on a short commute and decisive on a regular long run. Work out the longest journey you genuinely do without stopping, compare it with what the car realistically does today rather than its original brochure figure, and buy the gap. Whether you can charge at home will change your running costs far more than a few percent of battery capacity — whether to buy a used electric car works through that, and the pay-per-mile charge arriving in 2028 changes the running-cost arithmetic for every electric car already on the road.

Questions people ask

Does an MOT check an electric car’s battery health?
No. The battery is a mandatory inspection item on electric and hybrid cars, so it is not ignored, but the DVSA inspection manual states that propulsion batteries "should be assessed visually only" and lists exactly three defects: insecure but unlikely to fall, insecure and likely to fall or short circuit, and leaking. Capacity, range and state of health are not measured. A car with a heavily degraded battery passes its MOT on that item as long as the battery is secure and not leaking. This is the position in Great Britain; Northern Ireland’s test is run separately by the DVA.
Is a battery health certificate required when selling a used EV in the UK?
No. There is no UK legal requirement for one. We have found no government scheme that issues one and no UK rule defining what a certificate must measure or how. Several private companies sell battery health reports and some dealers provide them voluntarily, which is useful, but a certificate is a commercial product rather than a regulated document. Read what any given report actually measured before treating it as authoritative, and note that claims about certified cars selling for more or faster generally originate with the companies selling the certificates.
What does a manufacturer’s battery warranty actually guarantee?
Typically that the battery will not fall below a stated percentage of its original capacity within a stated number of years and miles — a separate promise from the main vehicle warranty, usually longer, and one that covers degradation past a threshold rather than degradation as such. The threshold, the term and the mileage cap all vary by manufacturer, and some publish them inconsistently across their own pages. Because it is the remaining term that matters on a used car, check the terms for the specific car and its registration date with the manufacturer rather than relying on a figure quoted anywhere else, including here.
Can I see the state of health on the car itself?
Often, though not always in an obvious place. Many electric cars expose a state-of-health or battery-condition figure in a service or diagnostic menu, and some show it only to a dealer’s diagnostic equipment. An OBD reader with software written for that model can usually retrieve it. Treat a single reading with some care: state of health is a manufacturer’s own calculation rather than a standardised measurement, it varies with temperature and recent use, and two cars’ figures are not strictly comparable.
What can I check on a test drive without any equipment?
Charge the car to a known percentage and compare the predicted range against what the car achieved new, remembering that the prediction moves with temperature, driving style and heating use, so it is an indicator and not a measurement. More telling is behaviour on a rapid charger: a healthy battery accepts a high rate at a low state of charge and tapers as it fills, whereas a battery that never reaches a decent rate, or that tapers very early, is worth asking about. A battery that has spent its life on rapid chargers is also a fair question to put to the seller.
How much does battery degradation matter on a used electric car?
It matters in proportion to the range you actually need, which is usually less than buyers assume. A car that has lost a tenth of its capacity has lost a tenth of its range, which is irrelevant on a thirty-mile commute and decisive on a regular two-hundred-mile run. Work out the longest journey you do without stopping, compare it against the car’s realistic range today rather than its original brochure figure, and treat the gap as the thing you are buying. Charging access matters more than degradation for most people.

Battery warranty terms differ by manufacturer, by model and by registration date, and some are stated inconsistently in manufacturers’ own material. Confirm the position for a specific car with the manufacturer before relying on it.

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