A charging bill can show more kWh than the increase you estimate from battery percentage. The bill measures delivered energy at a defined point; the battery display estimates stored charge. Conversion losses, heating or cooling, auxiliary systems and rounding can create a difference. That does not mean every discrepancy is correct: compare the right measurements before raising a query.

What does each number measure?

The charger’s kWh figure is an energy measurement for the session. State of charge is a percentage estimate from the car. A percentage-point increase multiplied by an advertised battery size is not a precise electricity meter.

Check whether the capacity you used is gross or usable. Gross capacity includes energy outside the driver-accessible operating window. Usable capacity can also change with conditions and battery ageing. A dashboard percentage may be rounded, making short sessions particularly difficult to estimate accurately.

Where can the extra energy go?

Energy conversion and electrical resistance produce losses. During charging, the vehicle may also use energy to manage battery temperature or run other systems. The ADAC’s charging-loss measurements distinguish AC and DC measurement boundaries and show why one universal loss percentage is misleading. AC conversion takes place inside the vehicle; DC conversion takes place in the station.

Do not assume every kilowatt-hour consumed by the station upstream of its billing meter appears on your bill. The location of the meter matters. Equally, not all energy supplied to the vehicle becomes usable battery energy.

Work through an illustrative session

Assume a nominally 60 kWh usable battery rises from 30 to 70 percent. The simple estimate is 24 kWh stored. If the session reports 27 kWh delivered, the difference is 3 kWh. That is about 11.1 percent of delivered energy, but it is not a laboratory measurement of loss because the capacity and percentages are estimates.

Check euros separately from kilowatt-hours

At a fictional €0.60/kWh, 27 kWh costs €16.20 before any additional fees. If the invoice is higher, inspect session charges, time fees and parking rather than attributing the entire price difference to energy losses. Use our idle-fee guide to understand time-based charges.

A five-part invoice check

• Match the date, station and connector with the session you actually started.

• Compare the billed kWh with the charger or session receipt.

• Check the tariff that applied to the app, card or direct-payment method used.

• Check start and end times against any time-fee rule.

• Distinguish pending payment reservations from settled transactions.

For direct-payment reservations, see charging without an app. A bank hold and a final invoice can coexist temporarily without representing two completed charges.

When should you ask for a correction?

Contact the billing provider when the connector, energy quantity, tariff or time does not match the session evidence. Attach the receipt, session ID and relevant screenshots. Ask for the underlying session data and an explanation of each fee. A repeated unexplained discrepancy across several comparable sessions deserves closer investigation; a rough battery-percentage calculation alone cannot establish overbilling.

To improve your budget, track purchased kWh per distance over several weeks rather than applying a guessed loss factor to every stop. Our existing charging-price comparison helps turn those records into a realistic monthly total.

Put the checklist into practice with StromNow

Use StromNow to find charging points, review prices and plan a suitable stop. Check the station details before connecting and keep your next charging decision in one app. Explore StromNow and download the app.

Editorial review: 5 September 2026. Check current station conditions before charging.