What is fast charging? What is rapid charging?
If you’re a newcomer to the world of electric cars, you may be puzzled by the different charging points and speeds available for your car. In simple terms, there are slow, fast and rapid chargers, with different connectors and rates of power. Understanding the differences between these is key for any new or potential electric vehicle owner.
All three charging methods will top up your electric or plug-in hybrid (PHEV) car with power, but the way they do so differs. More importantly for owners, so does the speed at which they recharge. As their names suggest, fast and rapid chargers work much quicker than slow chargers, meaning you’ll spend less time at the charging station and more time driving.
How electric car fast charging and rapid charging works
Electric-car batteries have to be charged with direct current (DC). If you’re using a three-pin socket at home to charge, it draws alternating current (AC) from the grid. To convert AC to DC, electric vehicles and PHEVs feature an built-in convertor, or rectifier.
The extent of the convertor’s capability to turn AC into DC partly determines the charging speed. All fast chargers, rated between 7kW and 22kW, draw AC current from the grid and rely on the car’s converter to turn it into DC. A typical fast AC charger can fully recharge small electric vehicles in three to four hours.
To speed up the process, charging service providers build and install rapid chargers. There are two kinds of rapid charging. Rapid AC charging uses more power, at 43kW, than conventional fast AC charging, but the process is the same – AC is converted into DC by the electric car's own converter.
The other means of rapid charging is DC current. In simple terms, rapid DC chargers supply DC current straight to the car, bypassing the converter, allowing the car to charge at higher rates of power. Rapid DC chargers are more expensive, which is why their popularity is only now growing. As of May 2020, there were over 2,100 rapid-charging locations in the UK.
While rapid AC chargers supply power at 43kW, rapid DC chargers work at 50kW or more. Tesla’s Supercharger network is a DC rapid-charging network, and works at 120kW. In comparison to fast charging, a 50kW DC charger will charge a 40kWh Nissan Leaf from flat to 80% in 30 minutes.
Below is a rough breakdown of the basic kind of charging speeds available:
|Slow AC||Fast AC||Rapid AC||Rapid DC||Tesla Supercharger|
Can any electric car use fast and rapid chargers?
The most common connectors for fast chargers are Type 2 connectors, which many electric cars and PHEVs are able to use. For those that don’t feature a Type 2 plug, some AC fast chargers also use a Type 1 or Commando connector.
All rapid AC chargers use a Type 2 connector, but because of the charging capacities for some electric vehicles, not all of them will be able to convert 43kW of AC power to DC. The good news is that your car will automatically limit the power to its maximum capacity, so you won’t harm your battery.
Whether your electric vehicle can use DC rapid charging depends on two factors: its maximum charging capacity and which connector types it accepts. Rapid DC charging uses either CCS or CHAdeMO connectors (Tesla’s Superchargers use Tesla’s own Type 2 120kW DC connectors).
Look at your car’s manual or brochure to find out which connector it has. The good news is that nearly all rapid DC charging stations in the UK offer both CCS and CHAdeMO connectors, so you won't be stuck with the wrong one.
Are rapid chargers more expensive to use than fast chargers?
Different charging networks charge different fees for using their rapid chargers. For example, Ecotricity, a major provider of charging stations on the UK motorway network, charges 30p per kWh. Polar Plus, another provider, charges users differently with a £6 per 30 minute fee. Most providers charge between 25 and 35p per kWh. For comparison, the average domestic electricity price in the UK is 14p per kWh.
Where to find rapid chargers
Rapid-charging stations are often located in their own sites, so it’s worth getting on to www.zap-map.com for guidance on where to find the nearest fast or rapid-charging station.
Use the map to type in your postcode, and then use the filter at the left-hand side to identify the charging speeds and the right connector type for your vehicle. The map will also show how much each station charges, whether the charging station requires a subscription or loyalty card, and even if the station is in use.
Alternatively, both electric cars and PHEVs usually have their own database of charging stations built into the manufacturer's sat nav system.
Will frequent fast or rapid charging damage my battery?
Lithium-ion batteries, the type commonly found in electric cars and PHEVs, deplete over time, just like any other form of battery. And while the batteries found in laptops and mobile phones can be damaged if they're charged at high power consecutively, electric vehicle batteries won’t.
This is because manufacturers have built in safety systems to prevent damage from frequent use of rapid or fast charging. For example, the rate of charge can be automatically lowered if the car thinks too much power is being supplied to the battery too often.