Mazda electric vehicle driving on a coastal road

EV Battery Check · £9.99

EV Battery Health Check

Check a used electric car's battery health before you buy — estimated range retention, real-world range now vs when new, and how much battery warranty is left. Battery data powered by ClearWatt.

Estimated battery health & range retention vs when new
Battery health grade where a manufacturer test record exists
Expected real-world range now vs the official WLTP figure
Remaining battery warranty in miles & months
Usable & total battery capacity (kWh)
Full refund if we can't generate your report

EV Battery Check

What an EV battery health check tells you

On a petrol car, you check the mileage and the service history. On an electric car, the number that really decides value is one you can’t see: the health of the battery. It’s the most expensive part to replace, and there’s no legal requirement for a seller to show you its condition.

Our battery check estimates that condition before you commit — how much range the car should still hold, how that compares with when it was new, and how much battery warranty is left. It needs only a reg and the current mileage, so you can run it straight from a listing.

Battery-health grade (where a test record exists)
Estimated range retention vs when new
Expected real-world range now
Official WLTP range, side by side with real
Remaining battery warranty (miles & months)
Usable & total battery capacity (kWh)

Sample readingPowered by ClearWatt

Estimated battery health

A+

Estimated range now: 203–220 mi
Range when new (WLTP): 292 mi
Battery warranty left: 65,000 mi · 59 mo

See a full sample report

What the battery check shows

The battery and range reading is the paid core of every report. The same £9.99 check also includes charging, running cost, efficiency and spec where we hold that data — see the full Used EV Check.

Your battery readingIncluded

Battery health & range

Battery-health grade

Where a record exists

A letter grade such as A+, shown where a manufacturer battery test record exists for the car.

Estimated range retention

How much of the car’s original range it’s likely to still hold, as a percentage, from aggregated real-world test data.

Expected range now vs when new

The miles this specific car should realistically do today, and how far below its when-new range that is.

Range performance (WLTP vs real)

The official WLTP figure the car was sold on, set against the estimated real-world range now.

Remaining battery warranty

How many miles and months of manufacturer battery cover are left, with an Active / Expired badge.

Battery capacity

Usable and total capacity in kWh, and the WLTP range the car was rated for when new.

The mileage that informs it

Provided by the DVSA

MOT mileage history

A mileage timeline from official MOT readings — both an independent cross-check and a direct input into the range estimate above.

Powered by ClearWatt. Estimated range is based upon aggregated test data and actual vehicle performance may vary. For more information please consult ClearWatt’s Terms and Conditions. MOT and mileage history is provided by the DVSA.

Understand the numbers before you buy

What is battery State of Health, and how do we estimate it?

State of Health (SoH) describes how much of a battery’s original capacity remains. A brand-new pack is at 100%; as it ages and is used, that figure slowly falls. A true SoH reading needs a physical test with the car plugged in — which you can’t do from a listing, before you view.

So we do the next best thing. Using aggregated real-world data from thousands of electric cars, plus the age and mileage of the exact car you’re checking, we estimate how much range it’s likely to still hold versus when it was new. Where a manufacturer battery test record exists, we also show a health grade. It’s an estimate and a grade, framed honestly — not a measured SoH percentage — and it’s the reading no advert, V5C or MOT will give you.

What counts as normal degradation?

Some range loss is completely normal. Most EVs lose roughly 1–2% of capacity a year, though it varies with chemistry, climate and how the car has been charged — a lot of DC rapid charging and regularly sitting at 100% both accelerate wear.

That’s why mileage alone is a poor guide. A well-treated 80,000-mile car can have a healthier battery than a hard-charged 30,000-mile one. Seeing the estimated retention against the car’s age tells you whether its wear is normal for the type, or a red flag worth walking away from.

Real-world range vs WLTP — the honest gap

WLTP is the official lab figure a car is sold on, and almost nobody achieves it in daily driving. Your check shows the estimated real-world range for this car today next to that WLTP number, so you can judge the true, everyday distance before you buy — not after.

Every range figure is an estimate from aggregated test data, and your own results will still shift with driving style, weather and terrain. We never quote a guaranteed range.

EV battery warranties explained — and how to check what’s left

Manufacturers usually warranty the battery separately from the rest of the car, commonly for around 8 years or 100,000 miles, and often against capacity falling below a set threshold (frequently 70%). It’s the safety net on the single most expensive component.

The check shows how much of that battery cover remains, in both miles and months, with a clear Active or Expired badge — so you know whether the priciest part of the car is still protected, and can price the difference into any deal.

Why age and mileage drive battery health

A battery ages in two ways at once: calendar ageing over time, and cycle ageing from use. That’s why the check asks for the car’s current mileage — it turns a generic “this model when new” figure into an estimate for this specific car, at its real age and use, today.

We pre-fill the mileage from the latest MOT reading so you only have to confirm it, and the same MOT timeline doubles as an independent check that the odometer hasn’t been tampered with.

An estimate you can trust, framed honestly

We’d rather be straight with you than over-promise. The battery reading is an estimate built from aggregated real-world data and the car’s own age and mileage, with a health grade shown only where a manufacturer test record exists. It is not a measured State of Health.

“Estimated range is based upon aggregated test data and actual vehicle performance may vary. For more information please consult ClearWatt’s Terms and Conditions.”

MOT and mileage history is provided by the DVSA. And if we can’t produce your battery and range report, you’re refunded in full, automatically.

EV battery health questions

Can you really tell a used EV’s battery health from the reg?

We can give you a well-founded estimate. From the registration and the current mileage, we estimate how much of the car’s original range it’s likely to still hold, and show a battery-health grade where a manufacturer test record exists. It isn’t a physical, plugged-in test — but it’s the read you can get before you view the car.

Is this a measured State of Health (SoH)?

No. We show an estimated range-retention figure and a health grade where a test record exists, not an OBD-measured SoH percentage. A measured SoH requires diagnostic access to the car itself.

What’s a normal amount of battery degradation?

Roughly 1–2% of capacity a year is typical, though it depends on the car’s chemistry, climate and charging history. The report shows the estimated retention against the car’s age so you can judge whether its wear is normal.

What if there’s no battery test record for the car?

You still get the estimated range-retention figure, expected range now versus when new, and remaining warranty. The letter grade is only shown where a manufacturer test record exists for that specific car.

How is this different from the Used EV Check?

It’s the same £9.99 report — this page just leads with the battery-health story. The full Used EV Check page covers the whole report, including charging, running cost, efficiency and spec, where we hold that data.

What if you can’t produce my report?

If the battery and range data isn’t available for your car, we don’t produce a report and you’re refunded in full, automatically.