How do electric cars charge?

Electric cars have large onboard batteries, with capacities ranging from 40 kWh to over 100 kWh (with some vehicles falling outside of this range at either end). Like your phone, tablet, or laptop, these batteries must be charged up when they run down.

In principle, charging an electric car is just like charging any other battery. You plug the car’s charging cable into a suitable power source, and the battery charges using electrical energy transmitted along the cable.

There are a few other things to know that can help you charge your car faster and cheaper and better understand what’s happening inside your vehicle while it is charging up.

Types Of Electric Car Chargers

There are several types of electric car chargers. Type 1 and Type 2 connectors are the earliest examples of mass-market EV charging connectors, along with standard 3-pin plugs that allow you to charge slowly from a standard domestic mains plug.

Over time, faster, more powerful connectors have been developed. These include:

• Combined Charging System (CCS) plugs that feature a Type 1 or 2 connector with additional large DC pins.
• CHAdeMO connectors were developed in Japan and named after the idea that there is just enough time for a cup of tea while the vehicle charges.
• Tesla Supercharger connectors are proprietary charging connectors found only on Tesla electric cars.

While the maximum power rating, pin layout, and use of AC vs. DC charging varies, all these electric car chargers operate by attaching the car to a mains electricity supply and transferring electrical potential energy into the battery.

Power Ratings Of EV Chargepoints

The more powerful the EV chargepoint, the faster the vehicle will charge, with a fairly direct relationship between the two.

The latest electric car makes and models are compatible with some of the highest-power chargepoints. This allows them to charge much faster, even though they typically have much higher-capacity batteries.

Electric cars usually have built-in limits to ensure they do not draw too much power, which could damage the electronics of the car and helps avoid overcharging the battery. However, it’s still sensible for the owner to avoid plugging into a charger that is not rated for the vehicle.

Although specific power ratings vary, the following list gives an approximation of those in common use:

• 2.3 kW – Standard 3-pin domestic electricity supply
• 3.6 kW – ‘Slow’ domestic wall chargepoint
• 7.2 kW – ‘Fast’ domestic wall chargepoint
• 22 kW – ‘Faster’ domestic wall chargepoint
• 50 kW – ‘Rapid’ public chargepoint
• 100 kW – ‘Ultra-rapid’ public chargepoint
• 150 kW – Tesla Supercharger V1 and V2
• 250 kW – Tesla Supercharger V3
• 350 kW – Ionity network

The top-end power ratings are constantly increasing, but this snapshot shows how the different chargers are spread out across the full range from just a few kilowatts to several hundred kilowatts.

Charging Via AC Vs. DC

As mentioned, more recent electric car charging cables include support to charge from either an AC or DC connection. High-power chargers typically use DC (direct current) to deliver charge directly to the battery.

In practice, you don’t need to worry too much about whether you are charging using AC or DC. This is thanks to the vehicle’s inverter, which we’ll look at in more detail below.

However, it’s useful to know if DC charging is available from a chargepoint. This will usually get you to a higher charge level faster, which is beneficial if you’ve had to stop to charge halfway through a journey and want to get back underway as soon as possible.

What Is An Inverter?

The charge stored in an electric car’s batteries is delivered as direct current (DC), but the motor operates on alternating current (AC). An ‘inverter’ is the component that turns DC into AC en route to the motor.

When charging, most modern EVs can plug into either an AC or a DC charge point. Combined Charging System (CCS) plugs include additional larger DC connections for even faster, higher-power charging.

If you plug into an AC charge point, the inverter in your car will convert that into a DC voltage, which can be stored in the batteries. Charging direct from a DC source bypasses the inverter and is usually significantly faster overall.

What Is A Converter?

You may have heard of a ‘converter’ rather than an ‘inverter’. In fact, these two components work closely together to manage the power running through an electric car.

While the inverter turns DC energy from the battery into an AC current to supply to the motor, the converter changes the voltage of that supply, just like an adapter or transformer.

Together, these two essential components mean the different systems onboard an electric car can all draw power from the battery, even if they need different operating voltages than each other or the battery itself.

Will My Car Charge Faster From A 350 kW Charger?

In short, yes — the higher the power rating of the chargepoint, the faster your car will charge. But it’s not quite as straightforward as that.

There are a few things to note here:

• More power will generally charge your vehicle faster, but different cars can have different battery sizes and give a different range for the same amount of charge.
• Your vehicle will have a maximum safe power rating to avoid damaging the electronics. The newest makes and models of electric cars typically support higher maximum charging powers.
• In most cases, the chargepoint will automatically deliver the maximum safe power to your vehicle, so that you can charge from high-power chargepoints (but it will not be any faster).

Remember, electric cars are designed to be driven by people who do not necessarily understand their onboard systems and electronics. This means plenty of failsafes are built in to improve compatibility and prevent damage to the sensitive electrical components.

All of this means you can charge with peace of mind from any compatible chargepoint, and just look out for those that offer your vehicle’s maximum power rating for the fastest ‘flash and dash’ recharge pitstops.