EV charging speeds: AC, fast and ultra fast

AC charging

AC chargers are posts and wall boxes that give your car mains power. The car's own onboard charger turns it into the direct current the battery stores, and that onboard charger sets the limit.

• Public AC posts give 7 to 22 kW.
• Most cars take 7 kW on a single phase supply, or 11 kW on three phase. A few take 22 kW.
• At 7 kW, a typical car adds about 40 km (25 miles) of range for each hour plugged in.

AC makes sense where you stay a while: at work, at the shops, at a hotel or overnight. Many AC posts are a socket only, so carry your own cable.

Fast charging

Fast chargers supply direct current straight to the battery, skipping the onboard charger. On ChargeAlong a fast site has a DC plug of at least 50 kW and below 150 kW.

A stop from 20% to 80% usually takes 30 to 60 minutes, depending on the car. A fast charger is often all a car with a smaller battery, or an older car, can use at full speed.

Ultra fast charging

Ultra fast sites have a DC plug of 150 kW or more, and some go to 350 kW. They are built along highways and in towns where people stop for a meal rather than a night.

If your car can take that much power, a stop from 20% to 80% often takes 20 to 30 minutes. Cars built on 800 volt systems can be quicker still; their makers quote under 20 minutes from 10% to 80% in good conditions.

Your car sets the pace

A charger offers power; the car decides how much to take. Four things set the pace of a stop.

• The car's peak DC power. Look for it in the handbook or the maker's specifications. Charging never goes above it.
• How full the battery is. Charging is fastest when the battery is low and slows as it fills.
• Temperature. A cold battery charges slowly. Many cars warm the battery on the way to a charger if you set it as the destination in the car's own navigation.
• Sharing. At some sites two bays share one cabinet, and power is split when both are in use.

Why stops end at 80%

Above about 80%, most cars slow their charging a lot to protect the battery. The last 20% can take nearly as long as the 60% before it. On a long trip, two short stops to 80% are usually quicker than one long stop to 100%, and they leave the charger free for the next driver.

How ChargeAlong sorts sites

A site's tier comes from its connectors as its source lists them, never from a network's own label, so two sources describing the same site agree. A site is in exactly one tier, its fastest: a car park with twenty AC posts and one 150 kW charger is ultra fast. Each site page lists every plug with its power, so you can see what else is there.

To check your car can use a plug, see the guide to plug types.