Used Electric Cars: How to Assess the Actual Condition of the Battery

Found a used electric car at an attractive price? Don’t just focus on the mileage and the condition of the body. One of the most important things to check before buying is the condition of the high-voltage battery. The range, charging performance, and overall driving comfort all depend on it.

Here are a few things you should check!

🔋 1. Check the battery's SOH

SOH (State of Health) indicates the battery’s condition relative to its original specifications. It can be checked using BMS diagnostics or a specialized service.

Important: A 100% charge displayed on the panel refers to SOC, not SOH. Even a battery that has already lost some of its capacity can be charged to 100%.

🚗 2. Don't just trust the range figure

"The screen shows 400 km—the battery is in perfect condition."

Not necessarily. The estimated range depends on previous driving habits, temperature, speed, and the operation of the climate control system. Therefore, this figure is only a rough guide, not a comprehensive assessment.

💻 3. Run a diagnostic test

Connecting to the BMS can reveal much more: SOH, high-voltage system errors, battery parameters, and—depending on the model—the status of individual cells or modules.

Significant discrepancies in cell parameters or active errors are a reason to conduct a more detailed inspection.

⚡ 4. Check the fast charging feature

Before making a purchase, it’s a good idea to stop by a DC charging station. Make sure the charging session starts without any errors and proceeds smoothly.

Don’t focus solely on the maximum kW rating: charging power depends on the charge level, battery temperature, and the specific car model.

🔎 5. Look under the car

The battery is located low in the vehicle, so be sure to inspect its housing while the car is on a lift. Severe dents, signs of impact, deformation, or suspicious repairs are serious red flags.

🛣 And be sure to take it for a test drive

Don’t just drive a few hundred meters—take a normal route. Check the energy consumption and how the charge level changes. Sudden, unexplained spikes in the percentage may warrant further diagnostics.

What should you check before buying? It’s easy to remember:

SOH → BMS diagnostics → battery inspection → test drive → DC charging check.

And most importantly: don’t judge the battery solely by the car’s mileage. Its actual condition is far more important than a nice number on the odometer. A few extra checks before buying can save you from much more expensive surprises afterward.