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.

Explained in

Charging hardware · Stop 06Why do cables get thicker at higher power?Current, not power, sizes a cable. Why heat grows with the square of current, why 800-volt cars need less of it, and when cables are cooled with liquid.

A cable has to carry its current without overheating. Two ways lead there:

From “Thicker, or cooled”, stop 06
  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 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.
  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. IEC (free preview by VDE Verlag): IEC TS 62196-3-1:2020, DC vehicle connector, inlet and cable assembly with a thermal management system: introduction and scope. https://www.vde-verlag.de/iec-normen/preview-pdf/info_iects62196-3-1%7Bed1.0%7Den.pdf. Checked 13 Oct 2026.