When you start exploring EV charging, you'll quickly encounter "AC" and "DC" charging. Understanding the difference helps you know what to expect at different chargers.
The Simple Explanation
AC (Alternating Current):
DC (Direct Current):
Why Does It Matter?
The Battery Needs DC
Your EV battery can only store DC electricity. This means AC must be converted to DC before it can charge the battery.
The key question: Where does the conversion happen?
AC Charging: Conversion Inside the Car
With AC charging:
The bottleneck: The car's onboard charger has limited capacity (3–22kW typically).
DC Charging: Conversion Outside the Car
With DC charging:
The advantage: No bottleneck from the car's onboard charger.
Charging Speed Comparison
| Charging Type | Typical Power | Range Added Per Hour | Best For |
|---|---|---|---|
| AC 3kW | 3kW | 10–12 miles | Emergency/slow backup |
| AC 7kW | 7kW | 25–30 miles | Home charging |
| AC 22kW | 22kW | 70–90 miles | Fast home/workplace |
| DC 50kW | 50kW | 150–180 miles | Public rapid |
| DC 150kW | 150kW | 300–400 miles | Motorway services |
| DC 350kW | 350kW | 500+ miles | Ultra-rapid charging |
Where You'll Find Each Type
AC Chargers
| Location | Typical Power | Use Case |
|---|---|---|
| Home wall box | 7kW | Overnight charging |
| Workplace | 7–22kW | Daytime charging while at work |
| Car parks | 7–22kW | While shopping/leisure |
| Lamp posts | 5–7kW | On-street residential |
| Hotels | 7–22kW | Overnight guest charging |
DC Chargers
| Location | Typical Power | Use Case |
|---|---|---|
| Motorway services | 150–350kW | Long journey stops |
| Service stations | 50–150kW | Quick top-ups |
| Supermarket rapid bays | 50–150kW | While shopping |
| Charging hubs | 100–350kW | Dedicated charging stops |
Connector Types
AC Connectors
| Connector | Where Used | Notes |
|---|---|---|
| Type 2 | Most home chargers, public AC | Standard in UK/Europe |
| Type 1 | Some older EVs (Leaf pre-2018) | Rare now |
| Three-pin (domestic) | Emergency charging | Very slow (2.3kW) |
DC Connectors
| Connector | Where Used | Notes |
|---|---|---|
| CCS (Combined Charging System) | Most modern EVs | Standard in UK/Europe |
| CHAdeMO | Older Nissan Leaf, some others | Declining |
| Tesla (proprietary) | Older Tesla Superchargers | Adapters available |
| CCS at Tesla | Newer Tesla Superchargers | Works with any CCS car |
Modern standard: Almost all new EVs use CCS for DC charging and Type 2 for AC charging.
Your Car's Limits
AC Charging Limit (Onboard Charger)
Your car has a maximum AC charging speed, regardless of the charger:
| Car | Onboard Charger | Max AC Speed |
|---|---|---|
| Nissan Leaf | 6.6kW | 6.6kW |
| VW ID.3 (standard) | 11kW | 11kW |
| VW ID.3 (optional) | 22kW | 22kW |
| Tesla Model 3 | 11kW | 11kW |
| Hyundai Ioniq 5 | 11kW | 11kW |
Example: If your car has an 11kW onboard charger, plugging into a 22kW AC charger will only give you 11kW.
DC Charging Limit
Your car also has a DC charging limit:
| Car | Max DC Speed | Notes |
|---|---|---|
| Nissan Leaf (62kWh) | 50kW | CHAdeMO |
| MG4 | 135kW | Good for price |
| VW ID.3 | 120–170kW | Varies by version |
| Tesla Model 3 | 250kW | V3 Supercharger |
| Hyundai Ioniq 5 | 220–240kW | Very fast |
| Porsche Taycan | 270kW | Among fastest |
Example: Plugging an Ioniq 5 into a 350kW charger will max out at ~240kW (the car's limit).
Cost Differences
AC Charging Costs
| Location | Typical Cost |
|---|---|
| Home (standard tariff) | 22–28p/kWh |
| Home (EV tariff) | 7–15p/kWh |
| Workplace | Free–20p/kWh |
| Public AC | 30–50p/kWh |
DC Charging Costs
| Network | Typical Cost |
|---|---|
| Gridserve | 49p/kWh |
| BP Pulse | 55–69p/kWh |
| Ionity (ad-hoc) | 69–79p/kWh |
| Tesla Supercharger | 40–55p/kWh |
| InstaVolt | 66–79p/kWh |
Key insight: DC charging is faster but more expensive. Home AC charging is slowest but cheapest.
Battery and AC/DC Charging
Why DC Fast Charging Gets Slower
DC chargers slow down as the battery fills:
| Battery Level | Typical DC Speed |
|---|---|
| 0–20% | Ramping up |
| 20–60% | Maximum speed |
| 60–80% | Slowing down |
| 80–100% | Much slower |
Why: Fast charging generates heat. The battery management system slows charging to protect battery health.
Practical tip: For DC charging, charge to 80% then move on — the last 20% takes disproportionately long.
AC Charging Is Consistent
AC charging is slow enough that battery heating isn't a concern:
When to Use Which
Use AC Charging When:
Use DC Charging When:
Common Misconceptions
"DC charging damages the battery"
Reality: Modern battery management systems protect the battery. Occasional DC charging is fine. Very frequent DC charging (daily for years) might increase degradation slightly, but the difference is small.
"I need DC charging at home"
Reality: Almost no one needs home DC charging. The equipment costs £15,000+ and requires three-phase power. 7kW AC overnight gives most people more than enough range daily.
"AC charging is too slow"
Reality: For home use, 7kW AC is plenty. An 8-hour overnight session adds 200+ miles. Unless you drive 200+ miles daily, you'll never use that much.
Summary
| Aspect | AC Charging | DC Charging |
|---|---|---|
| Speed | 3–22kW | 50–350kW |
| Location | Home, work, car parks | Motorway services, hubs |
| Cost | Cheapest | More expensive |
| Use case | Daily/overnight | Long journeys, quick stops |
| Connector | Type 2 | CCS |
| Battery impact | Minimal | Slightly more stress |
The bottom line: Most of your charging will be AC (at home or work). DC is for long trips and emergencies. Both work well — they serve different purposes.