# A Comprehensive Review of Developments in Electric Vehicles Fast Charging Technology
## 4 Electric Vehicle Battery Chargers Categories
### OFF-Board Charging  
Off-board charging involves replenishing EV batteries outside the vehicle itself, typically at external charging stations or infrastructure [143], as shown in Figure 5. Researchers are exploring off-board and DC-based charging methods for EVs due to their potential impact on power quality and efficiency [137]. Common off-board charging methods include public charging stations, DC fast charging (Level 3), and wireless charging (inductive charging) [117]. These methods have fewer conversion stages, making charging more efficient, especially with a DC power supply, which eliminates the need for AC-DC conversion and power factor correction stages. While DC chargers are not widely adopted in EVs yet, they offer the potential for the integration of solar PV power. Some studies propose dual-input EV chargers that can utilize both AC grid power and standalone PV systems, operating in grid-connected mode during low solar irradiation and in V2G mode during idle hours [138]. Off-board chargers can be divided into isolated and non-isolated converters, with isolated converters being preferred at higher voltage levels and non-isolated topologies being feasible for low power levels [65; 144; 145]. Off-board chargers include examples such as the Tesla supercharger network, strategically located along highways and major routes to offer high-speed charging for Tesla vehicles during long-distance travel, charging points providing both Level 2 AC chargers and DC fast chargers, which are commonly found in public parking lots and commercial premises for convenient charging options, various industries currently provide fast-charging stations supporting multiple charging standards like CCS and CHAdeMO, which are primarily located along major highways and urban areas, and home charging stations, installed by many EV owners at their homes for convenient overnight charging or charging during low electricity demand periods, typically including Level 2 AC chargers and being installed in residential garages or driveways.  
Figure 5: Illustrated on-board/off-board EVs fast charging.  
\begin{table}
\begin{tabular}{l l l l} \hline \hline
**Charging Methods** & \multicolumn{2}{c}{**Advantage**} & \multicolumn{2}{c}{**Disadvantage**} \\ \hline \multirow{6}{*}{On-board charger} & - & A lower rate of energy transfer (KW). & - & Slow charging times. \\  & - & Convenience (charge anywhere with an outlet). & - & Added weight and size to the vehicle. \\  & - & Weight is added to the EV. & - & Limited charging infrastructure compatibility. \\  & - & An on-board rectifier controls battery & - & May require specific outlets. \\  & & management system (BMS). & - & Potential battery heating issues. \\ \hline \multirow{6}{*}{Off-board charger} & \multirow{6}{*}{-} & \multirow{6}{*}{High energy transfer (KW).} & - & Limited flexibility (requires compatible \\  & - & High energy transfer (KW). & & charging stations. \\  & - & The problem of battery heating must be solved. & - & Potential challenges with the battery \\  & - & Potential enhanced BMS systems. & & management system. \\  & - & Fast charging speed. & - & Higher cost and complexity. \\  & - & Charger at higher power levels. & - & Charging station accountability. \\  & - & Reduces weight in the vehicle. & - & Limited ability to identify defective \\  & & & battery cells. \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparison between on-board and off-board chargers [142].