EV Onboard Chargers and Charging Speeds

EV Onboard Chargers and Charging Speeds

EV batteries are charged with DC (Direct Current) power. However, Level 1 and 2 home and public chargers – including the ChargePoint Home Flex – use AC (Alternating Current) power.

The onboard charger converts the AC power from the grid to DC power to be stored in the EV’s battery.

Onboard chargers are rated to convert a certain level of power into kilowatts (kW). The rating defines the speed at which the charger will charge your EV.


Charging Speeds


Let’s do a simple calculation to figure out how many kilometres can be added to an EV in one hour of charge:

  1. The ChargePoint Home Flex can be adjusted to deliver between 16 to 50 amps to any EV. This means the Home Flex can deliver up to 12 kW to your vehicle.
How did we get this?
16 amps X 240 volts from the outlet = 3.8 kW
32 amps X 240 volts from the outlet = 7.6 kW
40 amps X 240 volts from the outlet = 9.6 kW
50 amps X 240 volts from the outlet = 12 kW
2. However, you must remember that the EV’s onboard charger rating will dictate how much charge the vehicle can accept.


The range of an average EV will be greater in summer than in winter; typically, 5.5 km per kilowatt hour (kWh) in summer and 4.5 km per kWh in winter. To make it easier, we’ll use 5.0 km per kWh as our average range.

Typically, a PHEV (plug-in hybrid) has a 3.8 kW onboard charger, so it will gain a charge of approximately 20 km per hour (3.8 kW X 5.0 km per kWh range).

Most BEVs (battery electric vehicles) have an onboard charger of 7.6 kW; therefore they will gain a charge of roughly 40 km per hour.

New BEVs have onboard chargers up to 11 kW so they will gain a charge of approx. 55 km per hour.

By comparison, an EV with a 12 kW onboard charger will add roughly 60 km per hour. 

Therefore, one of the biggest advantages of the ChargePoint Home Flex is flexibility. Because the Home Flex can supply up to 12 kW or 60 km per hour, you can select the highest charging current that works with your electrical panel, while allowing for faster charging in the future if you purchase an EV with a higher-rated onboard charger.

If you experience your vehicle not charging as quickly as you expect, you should check the vehicle’s settings to ensure it is charging at maximum power.

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