EV Charging Infrastructure and Charging Procedures
What this domain covers
You must know AC and DC charging, connector types, the handshake between vehicle and charger, charging limits and the safety checks before and after a charge.
Core rules and concepts
- AC charging: the onboard charger converts AC to DC. Power is limited by the charger and the onboard charger rating.
- DC fast charging: the off-board charger supplies DC directly to the pack through the charge port and contactors; the BMS controls the current.
- Common connectors: Type 2 for AC, CCS2 for DC in India and Europe, CHAdeMO for some DC vehicles, and Bharat AC-001/DC-001 for small vehicles.
- Handshake: charger checks insulation, earthing, communication and permitted current before closing contactors.
- Charging profile: constant current, then constant voltage, then taper; 20–80% is usually fastest.
- Pre-checks: cable and connector damage, water ingress, earthing, vehicle state, no warning lamps.
Worked example
A car has a 7.2 kW onboard charger and is connected to a 22 kW AC charger. The car will draw at most 7.2 kW, not 22 kW. With a 40 kWh pack at about 7 kW, a 20–80% charge needs roughly 24 kWh, so about 3.4 hours ignoring losses and taper.
Traps that cost marks
Do not say a higher-rated AC charger forces more power into the car. Do not confuse AC and DC connector pins. Do not charge a damaged or wet vehicle. Do not assume DC fast charging always reaches 100% quickly; it tapers. Do not leave a charge session without checking that the connector is released and the flap is closed.