Electric Chargers for the Home Garage
Formula E racers used to swap out cars when their batteries were drained, but that’s hardly an answer for your daily commute.
And while additional high-tech roadside charging facilities will make electric driving more practical, it’s the availability of convenient home charging equipment that persuades many vehicle buyers to go electric.
“Home is the main charging location for most E.V. owners,” said Gil Tal, director of the Plug-In Hybrid and Electric Vehicle Research Center at the University of California, Davis. “Even in California, more than half of the E.V. owners are not using any out-of-home charging infrastructure. They are O.K. with just plugging in at home.”
Over 80 percent of electric vehicle owners charge at home, the Energy Department says, adding that “charging in a single-family home allows you to take advantage of low, stable residential electricity rates.”
Three methods of charging cars’ lithium-ion batteries are in use: Level 1, using a standard 110-volt outlet; Level 2, an upgrade to a 240-volt outlet; and DC fast-charging, which uses direct-current electricity. However, owing to the high cost and complexity of DC equipment, home use is typically kept to Levels 1 and 2.
Level 1 charging, with the plug-in cord that is standard on electric vehicles, can replenish the battery of some limited-range electrics and hybrids — like the Chevrolet Volt or Fiat 500e — overnight.
For cars with larger batteries, Level 1 is painfully slow. That category includes models with a range of over 200 miles, like the Chevrolet Bolt, the Nissan Leaf Plus, the Kia e-Niro, the Hyundai Kona Electric, the various Teslas, and most coming models. Charging a depleted battery for these would require days.
Level 2 devices, at 32 amps, can add about 25 miles of range per hour. Thus, a depleted 60-kilowatt-hour Bolt battery can typically be fully charged in 10 hours. A drained Tesla 100-kilowatt-hour battery will take about 14 hours.
Level 2 charging requires aftermarket equipment that operates on 240-volt AC household current, like some air-conditioners or other large appliances. A 32- to 40-amp charger sells for about $600, with feature-laden smart chargers topping $1,000. Portable chargers that provide about 16 amps of current are offered for less than $300, but as amperage and price go down, charging time goes up.
Level 2 chargers meant for outdoor installation are hard-wired to a 240-volt source. That will add $500 or more to the cost. Chargers for indoor use can be plugged into a 240-volt outlet. This might be the best choice for an owner with a 240-volt outlet in the garage, but installing one will cost about as much as hard-wiring a charger to the breaker box.
Most electric vehicle owners don’t drive over 200 miles on a normal day, so the battery isn’t fully drained by evening. In that case, refilling it on a Level 2 charger can take just a few hours. If the daily commute is only 20 miles and that mileage is rarely exceeded, the Level 1 plug-in might suffice, as would a portable 16-amp Level 2 charger. It gets easier if the office provides some charging stations.
Level 2 chargers for home installation are compact, and most have an 18- or 25-foot charging cord, so the vehicle doesn’t have to be parked next to the unit. More expensive Level 2 smart chargers can be switched on or off with a cellphone and programmed to charge when electricity rates are lowest, though many electric vehicles now come with firmware and apps that offer similar abilities with a basic charger.
Asked what improvements in home charging we might see in the years to come, Mr. Tal said Level 2 technology was reasonably mature. However, he does anticipate a market for chargers powered by solar panels that generate DC current, no complex inverters needed.
Source: nytimes
