AC vs DC Charging
Electric vehicle batteries store DC (direct current) electricity. The electricity supplied by the grid is AC (alternating current). This means AC power must be converted to DC before it can be stored in the battery. The key difference between AC and DC charging is where this conversion happens: in AC charging, the conversion happens inside the vehicle using its onboard charger. In DC charging, the conversion happens in the external charger, and DC power is delivered directly to the battery.
- AC charging: conversion inside vehicle — limited by onboard charger capacity (typically 7–22 kW)
- DC charging: conversion in external unit — not limited by onboard charger (50 kW to 720 kW)
- DC charging is faster because it bypasses the onboard charger limitation
- DC chargers are larger, more expensive and require more infrastructure
Charging Levels Explained
EV charging is commonly described in levels or modes, which indicate the power level and connector type used.
| Level | Power | Typical Use | Charge Time (60 kWh) |
|---|---|---|---|
| Level 1 / Mode 2 | 1.4–3.7 kW | Emergency home charging | 16–43 hours |
| Level 2 / Mode 3 | 7–22 kW | Home, workplace, depot | 3–9 hours |
| DC Fast (Level 3) | 50–150 kW | Public fast charging | 30–75 minutes |
| DC Ultra-Fast | 150–720 kW | Highway, commercial hubs | 8–25 minutes |
Connector Types
Different markets and vehicle types use different connector standards. The most common connectors in Europe and many emerging markets are Type 2 (AC) and CCS Combo 2 (DC). Understanding which connector your vehicle uses is essential for planning charging infrastructure.
- Type 2 (Mennekes): standard AC connector in Europe — used for home and public AC charging
- CCS Combo 2: standard DC fast charging connector in Europe — combines Type 2 AC with DC pins
- CHAdeMO: DC fast charging standard used by some Japanese manufacturers
- GB/T: Chinese national standard — used in China and some emerging markets
- NACS (Tesla/SAE J3400): North American standard, increasingly adopted in the US
Home and Depot Charging
For most EV users — whether private owners or fleet operators — the majority of charging happens at home or at a depot overnight. A 7 kW home wallbox or depot charger fully charges most EVs in 4–10 hours, meaning the vehicle is always ready at the start of the day. This is the most cost-effective and battery-friendly charging method. Fleet operators should size depot charging infrastructure based on the number of vehicles, daily energy consumption and available grid connection capacity.
Public Charging Infrastructure
Public charging networks provide charging at locations including car parks, retail centres, motorway service areas and on-street locations. Fast and ultra-fast DC chargers at motorway locations enable long-distance travel. For fleet operators deploying vehicles in areas without depot charging, public charging infrastructure is an important operational consideration.
Smart Charging
Smart charging systems manage when and at what rate vehicles charge, based on electricity prices, grid demand and operational requirements. For fleet operators with multiple vehicles, smart charging can significantly reduce energy costs by shifting charging to off-peak periods and managing load to stay within grid connection limits. Some systems integrate with renewable energy sources to maximise charging from solar or wind generation.
Key Takeaways
- 1AC charging converts power inside the vehicle — limited to 7–22 kW by the onboard charger
- 2DC charging converts power externally — enables 50–720 kW charging speeds
- 3Overnight AC charging covers most daily use cases for both private and fleet vehicles
- 4DC fast charging is for range extension during operations, not routine charging
- 5Smart charging reduces fleet energy costs by shifting to off-peak periods
Summary
EV charging uses either AC (converted inside the vehicle) or DC (converted in the charger) power. AC charging at 7–22 kW is ideal for overnight home and depot charging. DC fast charging at 50–720 kW enables rapid top-ups during operations. Most daily charging needs are met by overnight AC charging. Smart charging systems help fleet operators manage costs and grid load.