On a used petrol car the engine is the expensive unknown. On a used electric car it's the battery, and it's harder to judge, because there's nothing to listen to and nothing to see. The good news is that battery health is a number, it can be measured, and most EVs come with a battery warranty that outlives the rest of the car's cover. The trick is knowing which number to ask for and what it means.
What is EV battery health?
Battery health, usually called state of health or SoH, is how much energy the battery can hold now compared with when it was new, as a percentage. A battery at 90% SoH stores nine-tenths of its original capacity, so the car's real-world range is roughly nine-tenths of what it was.
It's the single most important number on a used EV, because range is the thing you'll live with every day and the battery is the most expensive part of the car. It's not the same as the charge level on the dashboard: a battery can be 100% charged and still be at 85% health, which means 100% of a smaller tank.
Every lithium-ion battery loses some capacity as it ages. Nissan puts it simply: "all electric cars will lose a small amount of capacity as they age". What matters is how much, how fast, and whether the warranty still covers it if the answer turns out to be too much.
How long do EV batteries last?
Long enough that the warranty is the useful guide. Most manufacturers now cover the battery for 8 years or 100,000 miles, separately from the rest of the car, and promise it'll hold at least 70% of its original capacity in that time. That's the industry's own statement of what it expects the battery to do, and they're paying for it if it doesn't.
Here's what the manufacturers' own UK warranty pages say:
| Make | Battery warranty | Capacity it promises to keep | Passes to the next owner? |
|---|---|---|---|
| Volkswagen ID. | 8 years / 100,000 miles | 70% | Yes, "can be passed on to future owners" |
| Kia | 7 years / 100,000 miles if registered to the end of 2023; 8 years / 100,000 miles from 2024 | 70% | Yes |
| MG | 8 years / 100,000 miles (terms issued January 2025) | Below 70% counts as excessive loss | Yes |
| Hyundai | 8 years / 125,000 miles on models first made before 2020; 8 years / 100,000 miles on the Kona Electric 2020 model year on | 70% | Hyundai asks to be told of a change of owner |
| Renault Zoe (owned battery, "i" versions) | 8 years / 100,000 miles | Registered from 1 March 2020: 80% for years 1 to 3, 70% for years 4 and 5, 66% for years 6 to 8. Registered before: 66% | Yes, a change of owner doesn't alter the terms |
| BMW i | 8 years / 100,000 miles | Not stated on the page we read | Not stated |
| Nissan Leaf (24kWh, 2013 European terms) | 5 years / 100,000 km | 9 of the 12 capacity bars on the dashboard | Not stated |
Check the exact terms for the car you're looking at, because they change by model year. Tesla's UK warranty page blocked our fetcher, so it isn't in the table; read it on Tesla's own site.
The Renault row comes with a catch that matters more than the numbers: it only covers Zoes that were sold with the battery. Many weren't, and on those the battery belongs to a finance company rather than the car's owner. Do you get the battery with a used Zoe? explains how to tell and how the lease transfers.
How do you check the battery health on a used EV?
Ask for a state-of-health figure from a proper test, and check how much battery warranty is left. You've got four ways to get the figure, from free to paid:
- The car's own display. Some cars show it. The Nissan Leaf shows battery capacity as bars on the dashboard, "up to a maximum of 12 when the car was new", so fewer bars means lost capacity. It's a rough guide rather than a measurement, but on a Leaf it's the first thing to look at.
- A dealer's battery report. Approved-used schemes increasingly include one: Volkswagen says it produces a battery health certificate on its approved used EVs, and BMW gives a Battery Health Quick Report with the state of health on every approved used electric BMW. If a dealer has one, ask for it. If a dealer won't produce one, ask why.
- An inspection with a battery test. The AA's Comprehensive and Advanced inspections include a hybrid or electric battery test, plus the charge port and the charging lead; its Basic tier is petrol and diesel only. Is a car inspection worth it? compares the tiers and prices.
- A specialist battery test. Independent testers plug into the car and read the battery management system, some over a full discharge cycle. These are the most thorough, but check what the test actually measures and that it's available in the UK before paying.
What is the advert not telling you?
Paste the advert text and the registration. We read it against the car's DVSA MOT history and our known-faults database, then tell you what the seller left out.
Check an advert now (free) →What is a good battery health percentage on a used EV?
Judge it against the warranty floor and the car's age rather than a single magic number. Most warranties promise 70% over 8 years, and Renault's newer Zoe terms promise 80% for the first three years, so a battery still in the high 80s or 90s at four or five years old has aged well, and one already close to the warranty floor in its first few years has aged badly.
Three things matter more than the percentage itself:
- How much warranty is left. A car at 80% health with four years of battery warranty remaining is a safer buy than one at 88% with six months left, because if the first one keeps falling, the manufacturer pays.
- Whether the figure is measured. A test from a dealer or an independent tester is evidence. An estimate from the range on the dashboard isn't, because range depends on temperature, driving style and how the last few journeys went.
- Whether the range is enough for you. A battery at 80% of a big pack can still beat a smaller pack at 100%. Work out the range you actually need, in winter, and check the car still does it.
Battery health is the biggest of the EV-only checks, but not the only one: what to check before buying a used EV covers battery ownership, charging and the rest.
Does high mileage ruin an EV battery?
Not on its own, and mileage is a weaker guide on an EV than on a petrol car. Batteries age with time as well as use, and how a car was charged and kept matters as well as how far it went, so two cars at the same mileage can have very different batteries. That's why a measured state of health beats any rule of thumb based on the odometer.
High mileage is also normal for an EV. Battery electric cars in England did more miles a year than any other fuel type in 2025, 9,400 on average by the Department for Transport's figures, so don't be put off by a busy one. What is good mileage for a used car has the full breakdown. Where mileage does matter is the warranty: most battery warranties end at 100,000 miles even if there's time left, so a high-mileage EV can run out of cover early.
You can't see a car's charging history, so ask the seller how they charged it, and treat the measured health figure as the summary of everything you can't see.
Do buyers actually worry about this?
A lot, and the used EV market is growing fast. The SMMT reported used battery electric car sales up 67% to 110,761 in the second quarter of 2026. In a survey published by the lender Startline in August 2026, 57% of potential buyers said they wouldn't buy a used EV without an independent battery check, 77% said they were worried about battery failure, and 76% about the cost of repair or replacement.
The same survey found 31% would buy without a check if a significant part of the original battery warranty was left, which is the right instinct. The warranty is the manufacturer's money on the line.
Hybrids have a traction battery too, smaller and with no plug, and it ages the same way. Ageing hybrid battery packs are one of the documented faults on our Toyota Prius page, and the Toyota Auris page covers the Auris Hybrid.
What can't any check tell you about an EV battery?
Its future. A state-of-health test tells you where the battery is today, not how it'll age from here, and it can't see a cell that's about to fail. That's why the warranty matters as much as the number: it's the only thing that covers what a test can't predict.
Which of this can a report do for you?
The honest bit first: our report doesn't measure battery health, and no report built from records can, ours or anyone else's. State of health lives inside the car's battery management system and the only way to read it is to plug into the car. If someone offers you a battery health figure from the registration alone, ask where it came from.
What a records check can do is everything around the battery. Our free scan reads the car's full DVSA MOT history, the same official record every check uses, so you get the mileage at every test plotted and any odd year flagged, which is what you need to work out how much of an 8-year, 100,000-mile battery warranty is left. It reads the advert against that record, so claims like "battery health 95%" or "full warranty" sit next to the car's real age and mileage rather than being taken on trust. And it checks the car against the known faults for that model, which on EVs include documented faults such as the Zoe's on-board charger failing and the early 30kWh Leaf losing capacity unusually quickly.
What it can't do is replace the test. For a car you're serious about, get the state-of-health figure in writing, from a dealer report, an inspection with a battery test or a specialist tester, and check the warranty terms for that model year on the manufacturer's own page.
So what should you actually do?
Run the advert and the registration through the free scan first, to check the mileage, the history and what the seller's claiming. Then ask the seller for a measured state-of-health figure before you travel. If the car's worth pursuing, the same report upgrades on the same link with nothing re-run, adding the questions to put to the seller and a figure to negotiate from, so nothing's wasted if the free scan says walk away.
