Buying a used EV: how to check the battery

Buying a used EV: what to look for in the battery

The market for used electric cars is growing rapidly, and so is the most important question before buying: how healthy is the battery? With a combustion-engine car, the mileage and service history reveal a lot about its condition. With an EV, the battery determines range, charging behaviour and resale value. It is one of the most expensive components in the vehicle, but it ages quietly and its condition cannot be seen or heard from the outside. Modern traction batteries last much longer than their reputation suggests. If you want to buy a used electric car, what you need most is reliable information about the battery's condition.

This guide shows you which metric really matters, how to have the battery's condition checked, what a battery certificate can tell you, and what to look for in the warranty and charging history. If you are unsure, however, we always recommend consulting a specialist before making a decision!

Why the battery determines value and range

The high-voltage battery is the heart of every electric car and, according to the ADAC, one of its most expensive components. It determines how far you can drive, how quickly you can charge and what the vehicle will still be worth in a few years. Unlike an internal combustion engine, a weakening battery does not announce itself with noises or oil leaks. It simply loses capacity gradually, and that is precisely what buyers cannot see from the outside.

Nevertheless, there is no need to be excessively wary of a used EV. An analysis by TÜV Nord and Carly involving around 50,000 measurements shows that most batteries are more robust than expected: the average score was around 96 points, and just under 10% of vehicles had a remaining value below 85. The important thing is to interpret wear correctly. It does not progress evenly: it is slow for roughly the first 90,000 kilometres and accelerates noticeably thereafter.

State of Health: the most important indicator of battery condition

The key measure is called State of Health, or SoH. Expressed as a percentage, it indicates how much of the original capacity is still available. An SoH of 100% corresponds to a new battery; a lower value means less usable range.

As a rough guide, the following classification has become established in the industry:

• 95 to 100%: battery in virtually factory-new condition, typical of very recent vehicles
• 88 to 95%: very good condition, typical after three to five years
• 80 to 88%: sound condition, often after six to eight years or high mileage
• 75 to 80%: borderline range; loss of range is noticeable in winter
• Below 75%: concerning; it is worth taking a closer look

A single state-of-health (SoH) figure says little on its own. It becomes meaningful only in relation to the vehicle's age, mileage and comparable models. For context, according to a TÜV Nord analysis from spring 2026, many relatively new group models such as the VW ID.3, VW ID.4, Škoda Enyaq and CUPRA Born still retain around 92 to 96% of their capacity after three to four years. So if you are buying a used electric car and choose a relatively recent model, you will often find a very sound battery.

Checking battery condition: battery certificates and measurement methods

A battery certificate provides written evidence of the battery's state of health. If you are buying a used electric car, it makes the SoH value transparent and comparable, gives you peace of mind and creates room for negotiation if the value is lower than expected. Particularly when buying from a private seller, where the contract usually excludes statutory warranty claims, an independent certificate is often the only reliable basis for assessing the battery.

Several independent organisations in Germany offer inspections, including ADAC in partnership with AVILOO, as well as TÜV Nord, TÜV Süd, DEKRA and GTÜ. Broadly speaking, there are three methods:

• Energy analysis (for example AVILOO, ADAC): The battery is thoroughly measured during everyday use. This takes longer but is considered particularly accurate.
• Measuring internal resistance (for example, TÜV Süd, DEKRA, GTÜ): a faster procedure that can often be carried out on site with mobile equipment.
• Reading out the battery management system (for example, with Mahle E-Health or Volytica): This retrieves the internally calculated value and takes just a few minutes.

Depending on the provider and method, costs range from an inexpensive DIY measurement using an adapter to around €150 for a detailed written certificate. One point to bear in mind: there is still no standardised SoH testing method. Different providers use different measurements and reference values, so results cannot always be compared directly. An independent test not commissioned by the seller provides the greatest clarity.

Manufacturer’s battery warranty: what matters when buying used

Anyone looking to buy a used electric car should check the manufacturer's battery warranty as well as the battery's current condition. For most brands, the market standard is 8 years or 160,000 kilometers, whichever comes first. Within this period, manufacturers generally guarantee that the remaining capacity will not fall below 70%. If it does, they repair or replace the battery.

Some brands go further. Mercedes offers 10 years or 250,000 kilometres on certain models such as the EQS and EQE; Tesla sets mileage limits of between 160,000 and 240,000 kilometres depending on the model; and Toyota and Lexus offer up to 10 years or very high mileage limits on some models. Always check the terms for the specific model.

Three factors are crucial when buying a used car:

• The warranty usually stays with the vehicle and passes to you as its new owner.
• Many manufacturers require a complete record of maintenance at an authorised workshop for this. Without one, your warranty claim may lapse.
• Normal ageing is not covered by the warranty. The warranty applies only if capacity drops below the guaranteed threshold or there is a genuine defect.

This matters because replacing a battery outside the warranty can cost several thousand euros, depending on the model. For a recently registered used car, however, this risk is low because much of the warranty period is often still remaining.

Greater transparency from 2026: Euro 7 and the digital battery passport

The market is gradually becoming more transparent. Under the Euro 7 emissions standard, newly type-approved models are expected to display their battery's state of health directly in the vehicle and make it readable via the diagnostic interface. The planned start date is 29 November 2026 for new type approvals and, probably, 29 November 2027 for all new registrations. In parallel, the EU Battery Regulation introduces the digital battery passport. From 18 February 2027, it is due to apply to new traction batteries above 2 kWh, making data such as condition, origin and materials available via QR code.

These dates are set by regulation, although the details may still change. What matters most to you as a buyer is the direction of travel: battery condition will finally become comparable. Until these standards apply across the board, an independent SoH test remains the safest way to document its condition.

Checklist: buying a used EV and assessing the battery

• Ask for an up-to-date battery certificate showing the SoH value
• Assess the SoH value in relation to the car's age, mileage and model
• If possible, choose an independent test not commissioned by the seller
• Check the remaining term and conditions of the battery warranty
• Have the complete maintenance history confirmed by an authorised workshop
• When buying privately, bear in mind that warranty liability is often excluded
• Do not treat the range shown on the display as proof of battery cell health

Smart charging keeps the battery healthy

How you charge affects battery ageing. The ADAC and many experts recommend keeping the charge level between 20% and 80% whenever possible in daily use, charging fully to 100% only when needed, and not leaving the vehicle parked in direct sunlight for extended periods during extreme heat. Frequent DC fast charging puts slightly more strain on the cells than slower AC charging.

The right balance matters. Charging mainly at home or at work and using fast chargers strategically while travelling helps preserve the battery. Modern battery management systems actively regulate temperature and charging power, so occasional fast charging is not a problem for battery life.

Discover JOLT: as a charge point operator, we bring ultra-fast charging to where you need it in everyday life: right into the city. Our charging stations deliver up to 360 kW of charging power, adding around 200 km of range in approximately 10 minutes. An integrated battery storage system makes this possible, enabling ultra-fast charging without costly grid upgrades. And because our locations are available around the clock, you can top up whenever it fits your day.

Conclusion: buy a used EV with confidence and the right knowledge

Buying a used electric car is a sensible decision today, provided you keep an eye on the battery. The SoH figure indicates its condition, a battery certificate provides reliable evidence, and the battery warranty offers extra protection. Check the battery's condition with an independent test, ask experts if you are unsure, and pay attention to the warranty and service history. This turns a perceived risk into a confident choice. And to help everything last a little longer, charge with JOLT from now on!

Find a JOLT charging station near you now and charge ultra-fast!

Sources

1. ADAC: Electric car batteries, service life and warranty. https://www.adac.de/rund-ums-fahrzeug/elektromobilitaet/laden/elektroauto-batterie/
2. ADAC: Used electric cars, what to look out for when buying. https://www.adac.de/der-adac/regionalclubs/hessen-thueringen/sicherheit-mobilitaet/gebrauchte-elektroautos/
3. ADAC: Euro 7 emissions standard, deadlines and requirements. https://www.adac.de/rund-ums-fahrzeug/autokatalog/abgasnormen/euro-7/
4. AUTO BILD: Used electric cars: how to check the battery before buying. https://www.autobild.de/artikel/gebrauchte-elektroautos-so-checkt-man-den-akku-vor-dem-kauf-21495483.html
5. AUTO BILD: Overview of manufacturers' battery warranties. https://www.autobild.de/artikel/grosse-haltbarkeit-von-elektroauto-batterien-20343233.html
6. firmenauto: SoH data make battery condition a factor in a vehicle's value (analysis by TÜV Nord and Carly). https://www.firmenauto.de/fahrzeuge/pkw/soh-daten-machen-den-batteriezustand-bei-gebrauchten-e-autos-zum-wertfaktor/
7. auto service praxis / TÜV Süd: SoH is not the same as SoH. https://www.autoservicepraxis.de/tuev-sued/soh-ist-nicht-gleich-soh-3548757
8. Volkswagen: High-voltage battery, warranty and service life. https://www.volkswagen.de/de/elektromobilitaet/batterie/garantie-lebensdauer.html
9. narravero: Digital battery passport from 2027. https://www.narravero.com/de/batteriepass