Key To Mass EV Adoption: Faster Level 2 Charging

By · April 25, 2013

For years, automakers have been trying to figure out what an electric car needs to offer before an average consumer will make the switch from gas to electric. Longer range and a competitive sticker price would help. But there's also a strong argument that speedy daily EV recharging times will make the biggest difference.

I’m not talking about rapid recharging with an expensive direct current charging station. What I mean is improving the speed of the onboard charging system included as standard with every electric car.

Nissan LEAF Charging

For the past couple years, Nissan LEAF owners have endured charging rates that add around 10 miles of range in an hour.

3.3 Kilowatts Is Too Slow

To keep manufacturing costs down, and to keep cooling requirements at a minimum, cars like the 2011 Nissan LEAF and 2011 Mitsubishi i came with 3.3-kilowatt onboard chargers as standard. That equates to a rate of between 8 and 15 miles of range added per hour of charging, depending on state of charge and the battery pack’s temperature.

While sufficient for overnight charging or charging at work, 3.3-kilowatt charging isn’t attractive to first-time electric car drivers used to refueling their car in a few minutes at the gas station.

Full-Scale Quick Charging Is Too Costly

Solutions like the CHAdeMO direct current rapid charging system favored by Nissan and Mitsubishi—as well as Tesla’s Supercharger network—offer a much faster recharging solution than onboard chargers. At 50 kilowatts, CHAdeMO compliant cars can recharge from empty to 80-percent full in as little as 30 minutes, adding between 50 and 60 miles of range. Meanwhile, Tesla’s Supercharger system can add up to 150 miles of range in the same time, thanks to 90 kilowatts worth of charging power.

Here’s the rub: while rapid charging systems are fast, they are also costly to install since they require high-power three-phase supplies in order to operate. The compromise between speed and cost lies somewhere in between the slow 240-volt Level 2 and expensive DC Quick Charging.

Onboard Flexible Charging

Enter Renault’s Zoe, Mercedes Benz’s Smart ForTwo ED, and now Volvo’s second-generation C30 electric prototype.

With onboard chargers capable of taking any type of power feed from 3.3 kilowatts single-phase, up to 22-kilowatts three phase, all three vehicles can recharge quickly from inexpensive European public charging stations without requiring a expensive, cumbersome, external chargers.

In the case of the Renault Zoe, even faster charging is possible, but only at the 43-kilowatt AC equivalent of the rapid charge stations championed by Nissan, Mitsubishi and Tesla.

The U.S. Solution Already Exists

The J1772 specification that every U.S.-market electric car uses allows for charging at up to 80 amps at 240 volts, provided of course that the onboard charger and car is capable of receiving that much power. Moreover, that's 80 amps at 240 volts single phase, or 19.2 kilowatts, making it easier to install than the European three-phase system. But while the specification allows for 19.2-kilowatt charging, no cars on the market today support that high a recharging rate.

Toyota RAV4 EV Charging

The Toyota RAV4 EV uses a 10-kW charger that is compliant with the J1772 standard. That adds 30 or more miles of range in an hour. Everyday charging can go even faster.

At the moment, the 2013 RAV4 EV is the fastest-charging J1772-compliant EV on the market, thanks to its Tesla-derived 10-kilowatt onboard charger. Meanwhile, 2013 models of Nissan LEAF, Ford Focus Electric, Fiat 500 EV and Honda Fit EV all offer 6.6 kilowatt charging, the equivalent of adding around 30 miles of range per hour of charging.

While 30 miles per hour charged is better than 15, it is still sluggish compared to what the J1772 would allow, and what drivers would like to see. Double the power of J1772 charging included as standard in EVs to between 14 and 16 kilowatts, and it becomes possible to recharge an electric car at a speed of around 60 miles range per hour charged. That makes it possible to recharge an electric car as quickly as it is drained, making trips beyond the range of a single charge much more practical.

This approach does not require the J1772 Combo connector. The J1772 specification already allows for high-power, single phase charging.

Now it’s time for automakers and charging providers to make use of that full specification in the next generation of EVs and charging stations. And then watch the market of potential EV buyers react favorably to news that fast, practical and affordable electric car charging is part of the deal.

New to EVs? Start here

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