EV-13 — Charging

ASSUMPTION — This lesson explains the charging architecture at the system level. Up-to-date standards/pricing are covered in EV-37 with current sources.

1. AC Charging

In AC charging, the grid AC is converted to DC by the on-board OBC (On-board Charger) before reaching the battery. Power is limited by the OBC and the EVSE.

FACT — The EVSE is not really a “charger”; it safely supplies AC power and communicates with the vehicle. The AC→DC conversion happens in the on-board OBC.

2. DC Fast Charging

In DC fast charging the station produces DC directly; the OBC is bypassed and energy goes straight to the battery, enabling much higher power.

3. The Charging Curve

Charging power varies with SOC: it ramps up, reaches a peak, then tapers for cell protection.

FACT — “Peak power” and “average charging speed” differ. Peak power stands out in marketing, but most of the session runs at lower power. When cold, the curve shifts down further.

4. Standards and Connectors

Region/standard	Type
SAE J1772 (Type 1/2)	AC
CCS1 / CCS2	DC (combined with AC)
CHAdeMO	DC
GB/T	AC/DC (China)
NACS	AC/DC (North America)

FACT — Vehicle-side and charger-side protocols differ; ISO 15118, IEC 61851, etc. define the communication (detail: EV-37).

5. FAQ

Does DC fast charging damage the battery?

FACT — Frequent, high-power DC charging can accelerate aging through temperature and C-rate, managed by BMS limits (EV-41).

Is home charging safe?

FACT — With proper EVSE, grounding, and installation, home charging is safe.

6. Summary

• In AC charging the OBC converts; in DC charging the station does.
• The charging curve is shaped by SOC and temperature.
• Peak power ≠ average charging speed.
• CCS, CHAdeMO, GB/T, and NACS are the main standards.

7. Sources and Verification Note

Standards are IEC/ISO/SAE-referenced; current revisions are verified in EV-37.

• IEC 61851, ISO 15118, SAE J1772.

Next Lesson

• EV-14 — Thermal Management: cooling, heating, heat pump, and preconditioning.