What happens in the seconds before charging starts?

A safety check with insulation test and connector lock, a negotiation of voltage and current limits, and precharge. Only then does current flow.

Explained in

EV charging fundamentals · Stop 04Why doesn't electricity flow immediately?Authorisation is approved, yet the display shows Preparing and power later falls on its own. Safety checks, the handshake and the charging curve explained.

Three steps run during Preparing. Only after all three does current flow.

From “What fills those seconds”, stop 04
  1. Why does charging power drop at 80%?As a rule of thumb, the lower the state of charge, the higher the possible power. Above about 80%, charging takes disproportionately long, which is why the range from 10 to 80% is the one that counts for fast-charging performance.
  2. Why does my car charge below the charger's maximum power?The smallest limit applies: the car's battery, the station's converter or the site's grid connection.
  3. Why is charging at home slower than on the motorway?At home, the car's onboard charger converts AC to DC. At a fast charger, the station does this at much higher power, so minutes replace hours.
  4. Are most public chargers fast chargers?No. About three in five public charge points in Europe are AC chargers up to 22 kW. About one in five belongs to a site with 150 kW or more.