Why do two cars at one charger get less power?

A charger that shares power divides it between its two outlets. A car that is fuller asks for less, so the power moves to the other car.

Explained in

Charging hardware · Stop 05Why do some chargers share power between plugs?A 300 kW charger with two outlets: how it divides its modules between two cars, and why that rarely means slower charging overall.

A car takes full power only for part of a session; as the battery fills, the power falls (see the charging curve). The national charging study for Germany models it that way: the highest power at about 30% state of charge, falling steadily towards 100%. With sharing, power that one car no longer needs goes to the next car, and a second car can start right away instead of waiting for a free charger.

From “Why share at all”, stop 05

Terms

  1. State of chargeHow full the battery is right now, in percent; not to be confused with the state of health.
  1. What is the difference between AC and DC charging?With AC, the car's onboard charger converts the current, which limits power, often to 11 or 22 kW. With DC, the charger carries the converter itself and can deliver far more.
  2. Which connector do public chargers in Europe use?AFIR requires at least Type 2 at public AC points and Combo 2 (CCS) at public DC points. One car inlet takes both: Type 2 above, two DC pins below.
  3. Why do fast chargers have such thick cables?A cable is sized for current, and heat grows with the square of it. At the highest currents, thermal management watches the temperature and carries heat away, so the cable stays manageable.
  4. What does charger uptime mean?Uptime is the share of time a charge point is online, available and delivers energy. At 97%, it may be out for about 11 days a year at most.
  1. Nationale Leitstelle Ladeinfrastruktur and Reiner Lemoine Institut: Ladeinfrastruktur nach 2025/2030: Szenarien für den Markthochlauf, new edition 2024, section 2.2.1: the charging curve used in the model. https://reiner-lemoine-institut.de/wp-content/uploads/2024/06/Studie_Ladeinfrastruktur-2025-2030_Neuauflage-2024.pdf. Checked 13 Oct 2026.