To charge the batteries, EVs are connected to the electric grid, which provides different connection options called “charging levels”.
At present standard, SAE J1772 defines six charging levels as AC Level I, AC Level II, AC Level III. AC Level III and DC charging are termed as fast charging. The only standards that currently set out specifications for fast charging are “JEVS” and “SAE J1772 Combo”. In parallel, Tesla has developed its own DC fast-charge system, “Tesla Supercharger”. Level I operates at 120 V AC while Level II uses 208 or 240 V AC and fast charging require 200 to 450 V DC.
The following Table-1 shows the different charging levels configuration that is certified by SAE standards.
|Charging Levels||Specification Details|
|AC Level I (SAE J1772)||120V, 1.4 kW (12 A)
120V, 1.9 kW (16 A)
|AC Level II (SAE J1772)||240 V, up to 182 kW (80 A)|
|AC Level III||480 V, 20 kW (150A) Single-phase and Three-phase|
|DC Level I||200-450 V DC, up to 36 kW (80 A)|
|DC Level II||200-450 V DC, up to 90 kW (200 A)|
|DC Level III||200-600V DC (proposed) up to 240 kW (400 A)|
The following Table-2 compares the three charging levels: Level I, Level II, Level III. It provides a detailed specification of the different levels of charging available in the world. From this, Level I is suitable for residential charging while Level III is suitable for commercial charging. Level I takes maximum charging duration whereas, Level III or fast charging takes the least duration. Hence, fast charging is preferred.
|Charging Level I||Charging Level II||Charging Level III|
|Charging Outlet||120 V||240 V||480V|
|Maximum Power Rating||2 kW||2- 20 kW (3.5 kW relevant for home charging)||20-50 kW|
|Time is taken to charge batteries completely||PHEV
7 to 10 hours
17 to 22 hours
3 to 4 hours
less than half an hour
|Charging Speed||Slowest of charging levels||Moderate of charging levels||Fastest of charging levels|
|Relevant for home charging||Relevant for home charging (3.5 kW) and commercial charging (20 kW)||Relevant for Commercial charging|
|Power Supply||Single-phase Supply||Single-phase Supply||Three-phase Supply|