E-car: How to reduce expensive charging losses and save money

Electric car drivers cannot avoid expensive charging losses in electric cars. But with these tips you will at least waste less electricity and save money.

The ADAC has investigated how much electricity is lost when charging e-cars at home at the socket or wall box and how the loss can at least be reduced somewhat. You can find this detailed charge loss test by the ADAC here. We summarize the most important tips.

This is how you reduce the charging loss when charging electric cars at home

  • Avoid charging at a household socket (only a charging capacity of 2.3 kilowatts is possible there) and instead use the full charging capacity of a wall box.

  • When charging with alternating current, the rule of thumb applies: the higher the charging power, the shorter the charging process and thus the time in which charging loss occurs. In order to avoid major charging loss, you should charge at a wall box with 11 or 22 kW. The battery should always be full as quickly as possible.

  • In winter, it should be charged as soon as possible after the end of the journey, while the battery is still warm.

That’s why there is charge loss in the first place

When charging, electric cars draw more energy from the power grid than they then store in the car batteries. However, the manufacturers of electric cars are silent about these charging losses, which cost e-car owners money every time they charge at home. The ADAC therefore measured and determined the charging losses when charging at a household socket and when charging at a wall box for Renault Zoe, Tesla Model 3 ( detailed test report ), VW ID.3 and Fiat 500e.

The result: The greatest losses – between 10 and 30 percent (rounded) – occur when charging at the household socket. The Renault Zoe in particular, which was criticized for its poor crash test results some time ago, performed extremely poorly with a loss of more than 24 percent, as the ADAC emphasizes.

With a wall box (with 11 kW), the losses drop to a maximum of around 10 percent thanks to the significantly shorter charging time in all e-cars tested. The most efficient was the Fiat 500e, which lost just over 6 percent.


At very low temperatures, individual electric cars, in exceptional cases, also draw energy from the power grid to heat their batteries, such as the VW ID.3. In these cases, the loss can increase to as much as 20 percent.

Both when charging at the household socket and at a wall box, the alternating current for the car batteries has to be converted into direct current. The onboard charger takes care of that. According to ADAC, this results in around 5 to 10 percent conversion losses in the form of heat.

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