Level 2 EV charging speeds depend on multiple interrelated factors:
Charger Output Power
The charger’s power output (3.3 kW to 22 kW in the U.S., up to 22 kW in Europe) directly impacts speed. Higher outputs like 19.2 kW can deliver ~75 miles of range per hour, while 7 kW provides ~25 miles/hour.
EV Onboard Charger Limits
The vehicle’s onboard AC-DC converter determines maximum charge acceptance. For example, a 7.2 kW onboard charger cannot utilize a 19.2 kW station’s full capacity.
Battery Capacity
Larger batteries (e.g., 100 kWh vs. 40 kWh) require more time to charge fully, even with identical power inputs. Charging a 60 kWh battery at 7.2 kW takes ~8-9 hours compared to ~2-3 hours for a 20 kWh battery.
State of Charge (SoC)
Charging slows as the battery nears full capacity (typically above 80%) due to battery management system protocols.
Environmental Conditions
Extreme temperatures reduce charging efficiency and may trigger battery conditioning systems that slow charging speed.
Key Comparison Table
| Factor | Impact Example |
|---|---|
| 19.2 kW charger | Charges 40 kWh battery in ~2.1 hours vs. 7 kW taking ~5.7 hours. |
| 60 kWh battery | Requires 2-3× longer charging than 20 kWh battery at same power. |
| Cold weather | Can reduce charging speed by 20-30% in extreme cases. |
| Onboard 11 kW limit | Restricts even 22 kW chargers to 11 kW charging. |
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-factors-can-affect-the-charging-speed-of-a-level-2-charger/
