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Used EV battery health: what a report shows
State of health (SoH) is a battery's current usable capacity expressed as a percentage of its capacity when new. Generational's report, for example, compares the battery's usable capacity with its capacity when new and estimates real-world range (EV Powered, 20 Jan 2026). Manufacturer warranties typically define a capacity floor (e.g. 70%) below which the battery is repaired or replaced within the warranty period (Tesla, Kia, VW, Renault, Peugeot UK terms). Aviloo notes the SoH reported by a car's own battery management system can be inaccurate, which is why independent tests exist. Industry testing of over 8,000 EVs found average SoH above 95%, with many cars over 100,000 miles retaining more than 90% (AM Online, reporting Electrifying/New AutoMotive/BatteryIQ campaign).
Where to get a battery health check
| Provider | What the report shows | Cost |
|---|---|---|
| Aviloo (via Kwik Fit and dealers) | Kwik Fit's check uses the AVILOO Flash Test: digital battery health certificate showing SoH, detailed battery analysis, comparison with comparable EVs and a plain-language summary. Aviloo's own site: independent SoH, check for anomalies down to cell level, QR-code verifiable certificate; its Premium Test (full discharge cycle, for private buyers via a rental box) is listed but UK availability/price not confirmed. | £39.99 at selected Kwik Fit centres (Kwik Fit page, Oct 2026). Aviloo direct UK consumer price: not confirmed. |
| ClearWatt | App-based checks; ClearWatt site describes independent evidence on battery health, history and real-world driving data, with range insights and benchmarking against same-model cars (details partly from customer reviews on its site). | EV Health Test £39.99 one-off; EV Check Plus (for used buyers) from £7.99 per report (clearwatt.co.uk/pricing, Oct 2026). What each includes in detail: not confirmed. |
| Generational | OBD-port device test taking minutes; compares usable capacity with as-new capacity, estimates real-world range and can flag potential pack faults (EV Powered, 20 Jan 2026). Its Battery Health Report/Logbook shows certificate, SoH %, original capacity and remaining battery warranty (Renewable Energy Magazine, 14 Sep 2026). Used by Motorpoint (21 sites) and offered via Maverick Diagnostics to about 6,000 independent workshops. | Not confirmed (mainly sold to dealers/workshops). |
| Altelium | Digital platform modelling data from several sources; certificate shows SoH/remaining capacity compared with expected degradation for that vehicle type; linked extended battery warranty offered via dealers (GardX EVerity) (Fleet World, undated, c. 2023). | Not confirmed. |
| AA vehicle inspection | Pre-purchase inspection of petrol/diesel, electric and hybrid cars. The Advanced inspection lists a 'Digital Battery Test' and diagnostic overview; the AA page does not state that this measures EV traction-battery SoH. A dedicated AA EV battery SoH certificate: not confirmed. | Comprehensive from £199; Advanced from £279 (Basic £110 is petrol/diesel only); 10% off for AA members (theaa.com, prices based on Jul-Aug 2026 bookings). |
| RAC vehicle inspection | General pre-purchase inspections (Basic, Comprehensive, Advanced with diagnostic check). No RAC EV battery state-of-health test found on rac.co.uk - not confirmed. | Basic from £132; Comprehensive from £225; Advanced from £290 (rac.co.uk, Oct 2026). |
| DIY / model-specific | Nissan Leaf: 12-bar capacity gauge on the dashboard (warranty threshold 9 bars). Renault Zoe: OBD dongle plus the CanZE app, or mobile diagnostics (Go Green Autos). General: OBD2 adapter plus apps; some cars show SoH in menus or manufacturer apps. | OBD2 adapters/apps under £50 (Electric Car Scheme, 22 Sep 2025); main-dealer Zoe diagnostic about £120-£180 (Go Green Autos, Oct 2024). |
Questions to ask the seller
- Ask for an independent battery state-of-health report (e.g. Aviloo via Kwik Fit, ClearWatt, Generational) and compare SoH with the manufacturer's warranty threshold (commonly 70%).
- Check how much battery warranty is left: most cover runs from first registration for a set number of years or miles (e.g. 8 years/100,000 miles), whichever comes first.
- Confirm whether the warranty transfers (Kia, Hyundai, MG, Tesla and Renault terms say it does; Tesla requires the transfer to be completed through Tesla).
- Check the service history - Kia, Hyundai and MG make warranty claims depend on servicing.
- For a Renault Zoe (or Nissan Leaf 'Flex'), confirm whether the battery is owned or leased: check for 'i' in the V5C model name and run a finance/HPI check; get the lease terms or buyout quote from Mobilize Financial Services before buying.
- Check outstanding safety recalls by registration on GOV.UK (e.g. Hyundai Kona battery recall; Jaguar I-Pace battery recall and capacity limit).
- Check MOT history on GOV.UK for mileage and advisories.
- Check which rapid-charging connector the car has (CHAdeMO on Nissan Leaf; CCS on most others) and whether rapid charging was fitted at all (some Zoe ZE40, early BMW i3 and Citigo e iV SE lack it).
- Check the charging cables (Type 2 and any 3-pin 'granny' cable) are included - replacements are costly.
- On a Leaf, count the capacity bars (12 when new; warranty threshold below 9).
- Check for ex-taxi, fleet, driving-school or rental use, which may mean heavier wear and more rapid charging.
- Check connected-app services are unlinked from the previous owner.
Buyer's checklist
- Get an independent battery health (state of health) report, or ask the seller for a recent one
- Check how much battery warranty is left (years and miles from first registration) and whether it transfers to you
- For a Renault Zoe or early Nissan Leaf, check whether the battery is owned or hired
- Check recalls on GOV.UK and that any battery recall work has been done
- Check the MOT history and mileage on GOV.UK
- Check the rapid-charging plug (CCS or CHAdeMO) and that rapid charging is fitted at all
- Make sure both charging cables are with the car
- Ask for the service history: some warranties need servicing on time
- Test drive from a full charge and watch the range estimate and any warnings
- Remember the Electric Car Grant is for new cars only
Prices checked 2026-10-16 from the providers' websites. Be EV Wise has no commercial relationship with these providers.
Frequently asked questions
What is a good battery state of health for a used EV?
There is no single cut-off, but warranties often guarantee at least 70% of the original capacity within the warranty period. Industry testing of over 8,000 EVs reported average state of health above 95%, with many high-mileage cars above 90%.
How much does a battery health check cost?
At the time of checking, the Kwik Fit Aviloo Flash Test cost £39.99 and ClearWatt reports started at £7.99; some dealers include a report with the car.
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