How to Measure an Electric Vehicle Battery?

How to Measure an Electric Vehicle Battery?

EV Battery Testing, Health Analysis, and Methods Used in Workshops

In electric vehicles, the battery is as important as the motor — in fact, even more so. Range, performance, charging time, and the vehicle's resale value depend directly on the battery's condition. That is why the question "How is an electric vehicle battery measured?" has become critical for both owners and workshops.

Battery measurement is not done by checking voltage alone. In a professional assessment, the battery's charge level, health status, cell balance, internal resistance, and actual capacity are analyzed together.

1. Battery Voltage Measurement (Basic Check)

Electric vehicle batteries are typically high-voltage systems operating between 300V and 800V. The first check is reading the voltage values of the battery pack and cell groups.

This can be done manually with a multimeter, or in professional workshops by reading Battery Management System (BMS) data through OBD-supported diagnostic tools.

This measurement checks:

• Total battery voltage
• Minimum and maximum cell voltages
• Differences between cells

Significant differences between cell voltages indicate battery imbalance and capacity loss.

2. SOC – State of Charge Measurement

SOC indicates the battery's current charge level. The percentage shown on the instrument cluster is SOC information.

SOC does not directly reflect battery health. It only shows how much energy remains in the battery. The BMS calculates this value using voltage, current, and temperature data together.

In other words, a 100% charged battery does not mean it is 100% healthy.

3. SOH – Battery Health Measurement (State of Health)

The most critical data in battery measurement is the SOH value.

SOH shows the battery's current condition compared to its original capacity.

For example: If the battery capacity was 60 kWh when the vehicle was new and testing shows it can now store the equivalent of 48 kWh, battery health is approximately 80%.

SOH is usually read using:

• Authorized service software
• Advanced diagnostic tools

This value is one of the most important criteria when buying a used electric vehicle.

4. Internal Resistance and Load Testing

As a battery ages, its internal resistance increases. When internal resistance rises:

• Performance decreases
• Heat generation increases
• Fast charging times become longer

That is why professional measurements test the battery under load, not only at rest.

These tests measure:

• Instantaneous voltage drop
• Charge and discharge power
• Temperature changes

This data reveals the battery's actual operating health.

5. Capacity Test (The Clearest Result)

The most accurate method in battery measurement is a capacity test.

In this test, the battery is:

• Fully charged
• Discharged in a controlled manner
• Measured for how many kWh of energy the system delivers

This method reveals the battery's true capacity. However, it takes a long time, requires professional equipment, and is performed in a workshop environment.

It is therefore usually applied during inspections and detailed service checks.

How Is an Electric Vehicle Battery Checked in Workshops?

In professional workshops, the following three-part combination is used in practice:

• Reading BMS data via OBD
• Checking cell voltage balance
• Performance and temperature analysis under load

This clearly reveals both the battery's current status and its long-term health.

Conclusion

Electric vehicle battery measurement does not simply answer "what is the charge level?" What really matters is how healthy the battery is, how balanced the cells are operating, and what the actual capacity looks like.

As the number of electric vehicles grows, battery measurement and battery health reports have become one of the most important areas of expertise for workshops.

Universal diagnostic tools such as Autel, Topdon, and Launch perform electric vehicle battery measurements reliably.

Contact us to have your electric vehicle's battery performance measured or to purchase the equipment needed to test electric vehicle batteries.