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Questions to ask when buying a used EV: battery checklist

Last updated · 35 models · every point sourced

Pick the model, say whether you are buying from a dealer or a private seller and roughly how old the car is. We build a list of battery questions for that car – test certificate, the car's own reading, warranty left, charging history, recalls and the points that matter for that model – that you can print or save as a PDF and take to the viewing.

A checklist, not advice. The answers are the seller's word. Only a professional battery test of the actual car tells you its condition, and only the manufacturer can confirm warranty cover (use the VIN).

The basic checklist (any EV)

1. Battery test and health reading

  1. (Dealer) Can you give me a recent independent battery health certificate (AVILOO, Generational, Moba or similar) for this car, before I commit?
    Dealers can buy these tests cheaply – Generational sells them to dealers from £29 per test – so it is a fair request. (Generational)
  2. (Private seller) Has the battery been independently tested? If not, can I (or a mobile tester) run a test before I buy?
    Options include a Moba postal kit that you plug into the OBD socket for about 5 minutes, or a mobile tester – one in West Yorkshire using Generational kit charges £90 plus call-out. (Moba, EVBatteryHealthChecker.co.uk)
  3. Can I see the full certificate with its verification link or QR code – and does the VIN, date and mileage match this car?
    AVILOO’s QR code opens the original certificate on AVILOO’s own site; Generational certificates carry a unique assessment ID and URL. A screenshot you can’t verify is weaker evidence. (AVILOO GmbH, Generational)
  4. What battery health (SoH) does the car itself report, and how was it read – dashboard, app, OBD tool or dealer diagnostic?
    The car’s own (BMS) figure and an independent test are worked out differently; AVILOO says the BMS value can be too high or too low. See how to read a battery certificate. (AVILOO GmbH)
  5. Does the report show cell voltage balance (the difference between the highest and lowest cell)?
    In about 10,000 UK used-EV tests, roughly 1 in 85 cars showed an imbalance above 50 mV that Generational says needs investigating. A wide reading is a reason to fully charge and retest, not proof of a fault. (Generational, Northwest Vehicle Inspections)
  6. Can the car be fully charged before the viewing or the test?
    Generational’s certificate advises charging to full, waiting at least 2 hours and retesting if cells look unbalanced; MG says a full slow charge is the only way for its battery to reach its balanced state. (Northwest Vehicle Inspections, MG Motor Europe)

2. Battery warranty

  1. When was the car first registered, and can you show the warranty booklet, the service record or the maker’s app with the warranty status?
    Battery warranties run from first registration (Volvo counts from first delivery) and end at a time or mileage limit, whichever comes first. Some makers tie cover to servicing – Nissan, for example, says you must follow its maintenance advice to keep the warranty valid. (Volvo Cars UK, Nissan UK)
  2. Look up the published battery warranty for the model – years, mileage cap and claim threshold – in our battery warranty checker, and confirm with the manufacturer using the VIN.

3. History and use

  1. How was the car usually charged – mostly at home on AC, or often on rapid (DC) chargers?
    There is no sourced rule for how much rapid charging is too much, but single cars vary a lot: in Bjørn Nyland’s measured tests a 2021 Model 3 Long Range (taxi) that did a lot of DC fast charging had 84.3% at 98,000 km, while an owner reported a DEKRA result of 93.0% at 228,000 km for an ex-taxi VW ID.4 charged only on an AC wallbox (single cars, n=1). Judge the answer together with a test result. (Bjørn Nyland / TB Test Results, Bolidenforum.de)
  2. Has it ever been a taxi, private-hire or fleet car?
    Commercial use can shorten the warranty – e.g. Hyundai’s battery warranty for taxi/private-hire cars is 5 years / 100,000 miles, and MG’s general warranty is shorter for private-hire cars. (Hyundai Motor UK, MG Motor UK)
  3. Have all recalls and software updates been done? Can I see the record?
    You can check for unfixed safety recalls for free with the registration number on GOV.UK (it also shows MOT history). Some battery-related software updates matter – see the model-specific points below. (GOV.UK)
  4. If you quote a range, how was it measured – and when?
    Don’t judge the battery by the range readout: it swings with temperature and driving, and some makers release reserve capacity so the displayed range stays stable while the battery ages. (Recurrent)
  5. (Dealer) Does your own used-car warranty cover the high-voltage battery, and for how long? Can I have that in writing?
  6. (Private seller) Is there any outstanding finance, or a battery lease or subscription that would pass to me?
    Some cars were sold with a leased battery (for example Renault Zoe and Nissan Leaf Flex), which comes with separate terms. (Renault UK, Nissan UK)

Points marked (Dealer) or (Private seller) only apply to that kind of sale.

After the viewing

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Get this specific car tested

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Model averages can't tell you about the car in front of you. An independent battery test (typically a short OBD plug-in test, some remote) gives an SoH figure and often a certificate you can use when negotiating.

Prices change – check the provider's site. Provider names are used for identification only.

FAQ

What should I ask a used EV seller about the battery?

Ask for a recent independent battery health certificate you can verify online, the battery health figure the car itself reports and how it was read, the first-registration date and any warranty paperwork, how the car was usually charged, whether it was a taxi or fleet car, and whether recalls and software updates are done. Then add the points specific to the model.

Can I ask a private seller for a battery test?

Yes. A private seller cannot usually produce a dealer certificate, but you can ask to test the car yourself before buying – for example with a postal OBD kit such as Moba’s (about 5 minutes plugged in) or a mobile tester. If the seller refuses any test, treat that as a reason for caution.

What if the seller has no battery certificate?

Ask what battery health the car reports and how it was read, look at the warranty that is left, and compare any figure with data for the same model and mileage. A reading from the car alone is the car’s own estimate; an independent test of that car is the only way to know its condition.

Is anything I enter stored?

No. The generator runs in your browser; the model, seller type, age and mileage you choose are not sent to us or stored, and no cookies are set.