EV Charging Losses: How Much Electricity You Pay For That Never Reaches the Battery
📅 Published on October 5, 2026
Information as of 05.10.2026, based on measurements of charging losses at household sockets and wallboxes by the German automobile club ADAC (2022 and August 2026) and ADAC's study on DC fast charging (May 2025), as published by trade media. All percentages are measured values for individual vehicles under test conditions – your own everyday results may differ.
When you charge an electric car, you never pay for exactly the amount of energy that ends up in the battery. Part of the electricity turns into heat along the way, and another part powers control units, cooling or battery heating while the car is plugged in. What you are billed for, however, is the energy drawn from the grid – via your household meter at a wallbox, or via the charger's meter at a public station. The difference is called charging loss, and you will not find it in any manufacturer's spec sheet.
In August 2026, ADAC published new measurements for five current electric cars. Together with an earlier test series from 2022 and a study on fast charging from 2025, the picture is fairly clear: how much is lost depends heavily on how you charge – and the gap between the best and the worst measured scenario is more than a factor of twenty. This article summarises the numbers, works out what they mean for the real price per kilowatt-hour and shows how to keep charging losses low in everyday life.
Key points at a glance
- Household socket (2.3 kW): The highest losses. In ADAC's 2026 test they ranged from 12.7 to 15.3 percent for four of the five cars – and reached 24.2 percent for the Mercedes CLA 350 EQ.
- Wallbox at reduced power (4.2 kW, typical for solar surplus charging): Below 13 percent for all five test cars; the Renault 5 managed 8 percent.
- Wallbox at full power (11 or 22 kW): Below 7 percent for all test cars, with a best value of 5.1 percent (Renault 5).
- DC fast charging: According to ADAC only 1 to 4 percent with a warm battery, but 6 to 10 percent with a cold one, because the battery has to be heated first.
- You always pay for the loss: It is included in the energy the meter records – at home and at public chargers alike.
Where charging losses come from
A traction battery stores direct current (DC). Household sockets and wallboxes, however, supply alternating current (AC). When charging with AC, the charger inside the car – the on-board charger – therefore has to convert it. According to ADAC, this conversion loses roughly five to ten percent of the energy as heat.
A second effect is often underestimated: throughout the charging session, part of the vehicle's electronics stays active. Control units and the 12-volt system need power, and depending on the situation so does battery thermal management. ADAC puts the consumption of the components that control the charging process at 100 to 300 watts. This base load accrues per hour – not per kilowatt-hour. The longer a session lasts, the more it adds up. That is exactly why slow charging from a household socket is so inefficient: at 2.3 kW a charge takes many times longer than at an 11 kW wallbox, and the base load keeps running the whole time.
Third, when charging at home there is the cable between the meter and the socket. According to ADAC, the German installation standard DIN VDE 0100 already allows for up to four percent line loss there – especially with long supply cables to a garage or carport.
At a DC fast charger, the conversion inside the car is not needed because the charger already supplies direct current. Instead, the battery has to be within a certain temperature window to accept high charging power. If it is cold, it gets heated – and that energy also comes from the charger without ending up in the battery.
ADAC's 2026 measurements: five current EVs compared
For the study published in August 2026, ADAC charged the Renault 5 E-Tech, the Mercedes-Benz CLA 350 EQ, the VW ID.7 Tourer, the Volvo EX30 and the Tesla Model Y in three scenarios: from a household socket at 2.3 kW, from a wallbox limited to 4.2 kW (as when charging with surplus solar power) and from a wallbox at the highest AC power each car supports, 11 or 22 kW.
| Charging method | Charging loss in ADAC's 2026 test |
|---|---|
| Household socket, 2.3 kW | 12.7 to 15.3 % (VW ID.7 Tourer, Volvo EX30, Renault 5, Tesla Model Y), Mercedes CLA 350 EQ: 24.2 % |
| Wallbox, limited to 4.2 kW (solar surplus) | Renault 5: 8 %, other models 9.1 to 12.8 % |
| Wallbox, maximum AC power (11 or 22 kW) | all below 7 %, Renault 5: 5.1 % |
Two things stand out. First, the spread between charging methods: for the same car, the loss at a household socket can be more than twice as high as at a wallbox. Second, the differences between models: the Renault 5 was the most efficient in both wallbox scenarios, while the Mercedes CLA was by far the least efficient at the socket. How much a car consumes "on the side" while charging is therefore partly a matter of vehicle engineering – and that is precisely the information manufacturers do not publish so far. ADAC is therefore calling for charging losses to be disclosed transparently for the different charging options, and refers to the Green NCAP database for details on individual models, whose ratings also take charging losses at a home wallbox into account. According to Green NCAP, around 60 vehicles are assessed each year.
For comparison: ADAC's 2022 measurements
Back in 2022, ADAC tested four models that were common at the time: the Renault Zoe, Tesla Model 3, VW ID.3 and Fiat 500e. At a household socket, the Zoe lost a good 24 percent, the Model 3 15.2 percent, the ID.3 13.6 percent and the 500e 12.7 percent. At an 11 kW wallbox the figures fell to 6.3 percent (Fiat 500e), 7.7 percent (Model 3), 9 percent (ID.3) and 9.7 percent (Zoe). In winter, some vehicles also drew grid power to heat the battery, which pushed losses even higher.
Comparing the two series shows that the basic rule has not changed over the years: the household socket is the least efficient way to charge, and a high-power wallbox the most efficient for AC charging. All cars tested in 2026 stayed below seven percent at a full-power wallbox – but an outlier like the CLA at the socket shows that newer cars do not automatically charge more efficiently.
Fast charging: low losses – if the battery is warm
For a study published in 2025, ADAC charged a Tesla Model Y, VW ID.3, Hyundai Ioniq 6 and Renault Mégane at a 300 kW Alpitronic fast charger of the kind used in many public charging parks – at different temperatures. Sensors recorded how much power came from the grid and how much of it actually reached the battery.
The result: with a warm battery, charging losses were just one to four percent – generally lower than at a home wallbox. At low temperatures with a cold battery, they rose to six to ten percent because the battery first had to be heated. That energy comes from the charger and is paid for, even though it does not end up in the battery.
What about preconditioning, i.e. heating the battery while driving to the charger? It does reduce the loss incurred during the charging session, because the heating energy was taken from the battery beforehand. According to ADAC, however, the energy needed for battery heating stays the same – whether before or during charging. It is simply shifted. Its real benefit lies elsewhere: the battery can accept high charging power from the very start. More on this in our article on charging in winter.
💶 The price per kWh matters too – check what other drivers actually paid at a station before you plug in
Find charging stations near you →What charging losses mean for your real price per kWh
Percentages for charging losses look harmless. They become interesting once you translate them into price. If a certain share of the energy you pay for is lost, every kilowatt-hour that actually reaches the battery costs more than the price at the meter. The formula is simple:
Price per kWh in the battery = price per kWh at the meter ÷ (1 − charging loss)
This gives the following mark-ups – regardless of how high your electricity price is:
| Charging loss | Energy paid for to store 10 kWh | Effective mark-up on the kWh price |
|---|---|---|
| 4 % (DC, warm battery, upper end) | approx. 10.4 kWh | approx. +4 % |
| 5.1 % (best wallbox value 2026) | approx. 10.5 kWh | approx. +5 % |
| 10 % (DC, cold battery, upper end) | approx. 11.1 kWh | approx. +11 % |
| 15.3 % (socket, upper end of the four models) | approx. 11.8 kWh | approx. +18 % |
| 24.2 % (socket, Mercedes CLA 350 EQ) | approx. 13.2 kWh | approx. +32 % |
In other words: if you regularly charge from a household socket, you effectively pay around 15 percent to a third on top of your home electricity tariff, depending on the car. A supposedly cheap home tariff thus gets closer to a public charging tariff than you might think. Conversely, the gap between AC and DC prices narrows slightly, because less is lost at a fast charger with a warm battery.
ADAC derives a practical rule of thumb for public charging from this: if a kilowatt-hour costs the same at AC and DC chargers, fast charging is more cost-efficient because of the lower losses. If the kilowatt-hour is a few cents cheaper for AC charging, however, AC comes out cheaper. What matters, then, is always the actual price – not just the charging method.
Why the right price matters more than the last few percent
As interesting as the percentages are: at public chargers, price differences between tariffs, ad hoc charging and providers can be considerably larger than the few percent of charging loss with a warm battery. Under the EU's AFIR regulation, fast chargers of 50 kW and above deployed since April 2024 must have an ad hoc price per delivered kilowatt-hour and display it at the charger, which makes comparison easier. Our article on paying by card at EV chargers explains the details; for an overview of tariffs, see our charging card price comparison.
The problem: the price stored in a database does not always match what is actually billed. That is why Elunio shows not only the list price but also prices that other drivers have actually reported at a station – as an average of up to 20 reports from the last 180 days, together with the number of reports and the age of the most recent one. How dense these reports are depends on the region: coverage is currently best in Baden-Württemberg and the rest of the DACH region (Germany, Austria, Switzerland), while elsewhere some stations still have few or no reports. Background in the article Community prices vs. list prices.
Elunio's cost and charging-time estimates also account for charging losses – in a simplified way: they assume a flat 10 percent loss and a typical charge from 10 to 80 percent. Going by ADAC's figures, that is on the cautious side for fast charging with a warm battery and for a full-power wallbox, but too low for charging from a household socket. The estimate is meant as a guide, not an exact bill.
How to keep charging losses low
- Household socket only as a fallback: ADAC advises against charging regularly from a household socket for both safety and efficiency reasons. If you charge at home regularly, a permanently installed wallbox is more economical – more in our wallbox guide.
- Charge at full power at the wallbox: 11 or 22 kW (depending on the on-board charger) produced the lowest AC losses in the test. The shorter the session, the less base load accrues.
- Weigh up solar surplus charging consciously: Losses rise at reduced power – but in the test they stayed below 13 percent. Because the solar power is self-generated, it can still pay off. Our article on solar surplus charging covers this.
- In winter, charge right after driving: As long as the battery is still warm, it needs less heating. ADAC explicitly recommends this.
- Don't just top up at a fast charger: If the battery has been heated for the charging stop, ADAC says it is worth charging as much energy as possible, because the initial heating effort then carries proportionally less weight.
- Have the supply cable checked: Long cables increase losses. Whether an installation is suitable for regular charging is a job for a qualified electrician.
- Price before method: A good kWh price can matter more than a few percent less charging loss. Compare prices before you charge – with a charging card, ad hoc, and as other drivers have actually reported them.
Frequently asked questions
Do I also pay for charging losses at a public charger?
Yes, at least for the losses inside the vehicle. You are billed for the energy the charger delivers. Whatever of it turns into heat in the car or warms the battery is included in that amount. ADAC explicitly points out that customers pay for the heating energy during fast charging even though it does not end up in the battery.
Does my car show the charged energy correctly?
Many vehicles display how much energy has flowed into the battery – i.e. after losses. The meter of the wallbox or charger, by contrast, shows the energy drawn. The difference between the two gives a rough idea of the charging loss. How accurate the in-car display is depends on the manufacturer.
Does the trip computer's consumption include charging losses?
The trip computer refers to the energy taken from the battery while driving – charging losses are not included. If you want to know your real cost per 100 kilometres, you have to add them – depending on the charging method, as shown above, by a few percent up to around a third.
So is fast charging always more efficient than a wallbox?
With a warm battery, losses at the fast charger were lower than at the wallbox in ADAC's test. With a cold battery, that advantage shrinks. And for cost, what counts in the end is the price per kWh: whether fast charging pays off depends on how much more expensive the DC price is compared with the AC price or your home electricity.
Conclusion
Charging losses are not a myth, but they are no reason to panic either. At a full-power wallbox they were below seven percent for all five cars in ADAC's latest test, and at a fast charger with a warm battery just one to four percent. It gets expensive at the household socket: four of the five cars lost 12.7 to 15.3 percent there, and in the worst case almost a quarter – meaning you effectively pay up to around a third more per kilowatt-hour that ends up in the battery. If you charge at home regularly, use a wallbox; if you charge in public, look at the price first and the charging method second. And the most realistic indication of the price is what other drivers have actually paid at a station.
Sources: autohaus.de – "ADAC analysiert Ladeverluste: Wallbox spart Strom, Steckdose nur Notnagel" (06.08.2026) · firmenauto.de – "ADAC misst Ladeverluste bei fünf Elektroautos" (2026) · ecomento.de – "ADAC untersucht Elektroauto-Ladeverluste" (07.08.2026) · ecomento.de – "ADAC untersucht Ladeverluste beim Schnellladen" (27.05.2025) · autohaus.de – "ADAC-Test: Stromverluste durch Schnellladen vermeiden" (15.09.2022) · insideevs.de – "Ladeverluste bei Elektroautos: An Haushaltssteckdosen bis zu 30 %" (2022)