The used electric car market in the UK has grown quickly, with used EV prices falling and stock levels rising, making a used EV a realistic option for many more buyers. But an EV’s battery is by far its single most expensive component, and unlike an engine, its condition isn’t something you can judge just by listening to it run.
This guide explains what to check, what counts as normal wear, and when a battery reading should make you think twice.
Why Battery Health Matters When Buying A Used EV
A used electric car’s battery degrades gradually over its life, reducing the real-world range you’ll get compared to when the car was new. This is normal and expected, but the rate of degradation varies significantly between individual cars depending on how they were charged and used. Replacing a battery pack outside of warranty can cost thousands of pounds, in some cases a meaningful fraction of the car’s total value, which makes checking battery condition before you buy just as important as checking an engine or gearbox on a petrol car.
What Is State Of Health (SoH)?
State of Health, usually shown as SoH, is a percentage showing how much usable capacity a battery still has compared to when it was new. A battery reading 100% SoH has its full original capacity; one reading 85% SoH can only store around 85% of the energy it could when new, which directly reduces the car’s real-world range.
What SoH Percentage Is Normal?
As a rough guide for a well-maintained EV:
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Above 90%: Excellent, typical of a well-kept car around three to five years old
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85-90%: Healthy, and fine for most buyers
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Below 80%: Expect noticeably reduced range - check how much manufacturer battery warranty remains before buying
Some degradation is completely normal even on a healthy battery: roughly 4% in the first 50,000 miles is typical, with a further 2-3% drop over the next 50,000 miles. A reading significantly worse than this for the car’s age and mileage is worth investigating before you commit.
How To Check EV Battery Health Before Buying
Check The Dashboard Display
Many EVs show a battery or range screen in the dashboard settings menu, sometimes including a direct capacity percentage or health indicator. Check the settings and service menus during a viewing, not just the main range estimate.
Ask To See The Manufacturer App
If the seller has the car’s connected app set up, ask them to show you the current state of charge, estimated full-charge range, any stored diagnostic warnings, and recent charging history if available. This can reveal patterns - such as frequent rapid charging - that accelerate degradation.
Get A Professional Battery Health Check
The most accurate method is a dealer or independent EV specialist plugging into the car’s diagnostic port to generate a report showing total dischargeable energy and estimated degradation. This typically costs in the region of £100-£300, but is worth the outlay relative to the cost of an unexpected battery replacement.
Check Remaining Battery Warranty
Most manufacturers offer separate, longer warranty cover specifically for the battery pack, often seven or eight years. Confirm exactly how much of this remains on the specific car, in writing, before you buy - this can be more valuable than the general vehicle warranty.
Other Checks For A Used Electric Car
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Charging port condition and a full charging cycle if possible, since charging faults are a commonly reported issue on some models
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Tyre wear, which can be more uneven on EVs due to their higher weight and instant torque
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Software update history, since manufacturers frequently issue updates addressing known EV-specific faults
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Full service history, even though EVs have fewer service items than petrol or diesel cars
Checks To Run Before Buying Any Used Electric Car
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Battery state of health reading from the seller, a dealer, or an independent inspection
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MOT history for recurring advisories, once the car is old enough to require testing
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Mileage records for consistency with the car’s age
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Outstanding finance, which transfers risk to you as the buyer
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Write-off or stolen markers on the vehicle
Frequently Asked Questions
What SoH Should I Look For In A Used EV?
Above 90% is excellent for a car three to five years old, 85-90% is healthy and fine for most buyers, and below 80% means noticeably reduced range - at that point, check how much manufacturer battery warranty remains before deciding.
How Much Does An EV Battery Health Check Cost?
A professional diagnostic check from a dealer or EV specialist typically costs around £100-£300, which is minor compared to the cost of an unexpected battery replacement later.
Is Some Battery Degradation Normal?
Yes. Roughly 4% degradation in the first 50,000 miles is typical, with a further 2-3% over the next 50,000 miles. This is expected wear, not a fault - the concern is a reading significantly worse than this for the car’s age and mileage.
Should I Still Check A Used EV’s History Before Buying?
Yes. Battery health is specific to EVs, but mileage inconsistencies, outstanding finance and write-off or stolen markers matter just as much on an electric car as any other used vehicle, and a full vehicle history check can flag all of them.
A used electric car’s battery is its single most important - and most expensive - component to get right, and unlike an engine, its condition isn’t obvious just from a test drive. Checking the dashboard and app for a health reading, getting a professional diagnostic check where possible, and confirming remaining battery warranty in writing are the most effective ways to buy with confidence, alongside the same mileage, finance and history checks that matter for any used car.