A new study by NRG’s EVgo division finds that EV drivers who use a public charger while away from home prefer a DC fast charger 12 to 1 over a Level 2 charger. According to Electric Car Reports, EVgo came to that conclusion after monitoring usage at its charging stations in the San Francisco area. Most of its public charging stations offer a choice of either a Level 2 or a DC fast charger. The fast charger won out more than 90% of of the time.
The findings are important. Going forward, governments and business need to find the right combination of speed and cost to construct the public recharging facilities of the future. But first, let’s explore the different kinds of charging equipment available today and how people use them. Let’s begin by saying that all EV batteries use direct current. That means there must be a device known as an inverter either in the charger or in the car itself to convert AC to DC power. Every time a conversion takes place, about 3% of the available electricity is lost to heat and other factors.
The majority of EV owners charge their cars overnight at home. If they drive relatively short distances during the day, they may be able to use a Level 1 charger to replenish their battery. A Level 1 charger is equivalent to plugging an extension cord into a standard wall outlet. It uses 110 volt alternating current to get the job done, albeit slowly. Recharging a fully depleted battery can take 20 hours or more. Level 1 chargers are inexpensive and easy to install.
Level 2 chargers also use alternating current but supplied as 240 volts. That’s the same as most heavy duty household appliances such as dryers and electric water heaters use. Level 2 chargers cost more to buy and more to install, but they can recharge a depleted battery in 4 to 6 hours. That makes them ideal for workplaces, where employees expect to be inside working while there cars are being recharged.
DC fast chargers operate on 480 volts of direct current. They cost 4 to 5 times as much to buy and install. If there area many of them in one area, the local utility may have to upgrade its power lines to handle the load. But they can restore a depleted battery to an 80% charge in about 30 minutes, making them ideal for locations where shoppers expect to be away from their cars for only a short time.
The EVgo study shows that people are willing to pay for convenience. It makes no sense to install Level 2 chargers someplace where drivers will only be parked for a short time. It also make no sense to install DC fast chargers near places where drivers will be away from their cars for 6 hours or more. Companies who want to make money installing public charging systems will need to choose the right equipment for each location in order to be profitable.
Photo credit: EVgo