Pre-purchase inspection: check the battery of an electric car before you sign the contract
With a petrol car, you inspect the mechanical components. With an EV, there’s one thing in particular you inspect: the battery pack. Here’s what an electric car battery inspection reveals, and why the mileage can be misleading.
Which electric vehicle would you choose?
The same BMW iX3 twice. Car A has half the mileage and costs €2,000 more. Choose one, and we'll show you what the measurement said.
Choose one. After that, you will see what the measurement said.
These are not made-up examples. This concerns two 74 kWh BMW iX3s that we measured in June 2026, from different owners and with a difference of over seventy thousand kilometers. Between the two battery packs, there was four-tenths of a percentage point.
What actually makes the difference is charging behavior, climate, and how often fast charging was used. That is why the odometer is not a reliable indicator, whereas a measurement is.
Electric car battery inspection: what we measure
Four values together determine the judgment, and each tells a different story.
Remaining capacity
How many kilowatt-hours can still be added compared to the manufacturer's specification. This yields the percentage that will appear on the certificate.
Voltage per cell
The difference between the highest and lowest cell, in millivolts. A large difference indicates an unbalanced pack, even with a decent percentage.
Charging behavior
The number of charging cycles and how many of those were fast charges. Two cars with the same mileage can differ widely in this regard.
Temperature and condition
The temperature of the package during the measurement, ensuring the result is not distorted by a cold or recently charged battery.
— IN THE WORKSHOP
Electric car battery health: the only thing you cannot see
During a pre-purchase inspection, you check the car for things that are visible. Paintwork, tires, brakes, a look under the hood. The health of an electric car battery falls just outside of this: the pack is located under the floor, gives off no signal, and cannot be assessed just by looking at it.
That is why a measurement belongs during the inspection and not after. Three minutes at the diagnostic port provides the only piece of information that you would otherwise have to guess.
Electric car dealer battery inspection: at the seller or independent?
Many dealers are now able to perform diagnostics themselves. That is an improvement compared to five years ago, but there is an awkward side to it: the party selling the car is also the one providing proof that the car is in good condition.
A dealer battery inspection for an electric car is therefore not necessarily incorrect, but it is unverifiable for the buyer. An independent measurement is accompanied by a report linked to the chassis number that both parties can read.
In practice, this also works better for the seller. Anyone who provides the report no longer needs to explain that the battery is in working order.
What an inspection costs and when you do it
A full inspection including certificate costs € 80,- including VAT for private individuals. Car companies that perform the inspection themselves pay € 29,95,- excluding VAT per issued certificate, after a one-off purchase of the toolkit.
The best moment is before you sign. Bring the car to our location or to an affiliated partner, or have the seller provide the report. If in doubt about the outcome, you can always have us repeat the measurement.
Frequently asked questions about the pre-purchase inspection
How do I check the battery of a used EV?
By having the Battery Management System read out. That is the only source that tells you how much capacity is actually left.
How do I recognize a weak battery?
The voltage differences between the cells. These often reveal a problem sooner than the overall percentage.
Where can I have my car inspected?
At our location in Blaricum or at an affiliated partner. The location page contains the complete overview with directions.
What should I pay attention to regarding the battery condition?
On the combination of percentage, cell balance, and charging history. Any one of those three alone gives a distorted picture.
Want to know more? View all frequently asked questions in the knowledge base.
Have the battery inspected before you sign
Three minutes of measuring saves a discussion afterwards about a part that costs thousands of euros.