Why can the energy on a charging bill exceed the energy added to the battery?

The energy on a charging bill and the energy added to the battery describe different boundaries. Charging losses and supporting loads mean the two totals need not match.

For an illustrative process that adds 20 kWh to the battery at 90% efficiency, estimated input is 20 ÷ 0.90, or about 22.2 kWh. That efficiency is an assumption for the example, not a measurement for your car.

Use the billed quantity for the session’s electricity cost and add applicable fees. When comparing consumption, say whether the numbers came from a wall meter, a receipt or the vehicle display.