SAE International, formerly known to you and me as the Society of Automotive Engineers, is the most widely recognized standards organization for automotive technologies in the world. When it comes up with a “standard,” it’s usually the result of years of automakers bickering amongst one another until they come up with a plan that’s registered in a database for the auto industry to use.
It’s pretty clear-cut. Until it isn’t.
Back in the late 1990s, when electric cars made their first real resurgence—the GM EV1, Honda EV Plus, and original Toyota RAV4 EV—they all had different plugs for charging. In 2001, at the insistence of the California Air Resource Board, SAE International began finalizing what we now know as SAE J1772, which includes five prong inlets and grounding for 6.6 kilowatt-hours allowance. In 2009, the standard was updated, accommodating both Level 1 travel plugs and Level 2 high-capacity wall-mounted chargers. Europe adopted a system similar to SAE J1772 and refined for its continent’s needs, courtesy of Mercedes-Benz’s parent company Daimler and utility company RWE.
Japan hasdn’t wanted to play by the same rules, though. Tokyo Electric Power Company developed a DC quick charger of its own called CHAdeMO, which more or less stands for “charge on the move.” Nissan, Mitsubishi, and Subaru use it for smaller cars. Mitsubishi and Nissan have CHAdeMO plug-in ports in their cars alongside J1772 plugs for U.S.-bound models.
Stubbornly, Japan has carried CHAdeMO ports on its cars, despite the rest of the world straying away from it. In the U.S., there are fewer than 100 CHAdeMO quick charging stations; about 1,100 worldwide. Using one, often a driver is able to charge his or her car to 80-percent capacity or more in 30 minutes. That compares favorably to the three hours it takes to charge a Ford Focus Electric’s 23 kilowatt-hour battery or six hours it takes to charge a Leaf’s 24 with a standard Level 2 charger.
But other Japanese automakers, like Toyota, haven’t followed suit. Being that there’s no governing body supporting CHAdeMO, Toyota didn’t want to take the risk.
“There’s no standard behind it,” said 2012 Toyota RAV4 EV chief engineer Sheldon Brown at the launch of the new crossover. “Do you think it’ll be around in a decade?”
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With the RAV4 EV, Toyota opted to put only a single J1772 port into its vehicle, using an onboard 6.6-kilowatt charger to power up its vehicle. That’s why it can charge a 41.8-kilowatt-hour battery in under seven hours. The Nissan Leaf has just a 3.3-kilowatt charger, serving as a smaller conduit for which electricity to flow. It’s rumored in a refresh that the Leaf will be upgraded to 6.6 kilowatt system within the next few years.
The term “charger” is a bit of a misnomer in electric cars, as all of them have onboard management systems that actually charge the cars. A wall-mounted Level 2 port—what we commonly refer to as a car charger—is simply a means to get electricity from the grid into a vehicle. One can generate as many as 19.2 kilowatts of energy, which is only limited by the 3.3- or 6.6-kilowatt management system found built into today’s electric cars; most home units only make a fraction of that at present. A CHAdeMO charger can generate up to 62.5 kilowatts and often has a much greater electricity management capacity at this stage of electric car development.
So why is SAE J1772 becoming the predominant choice? It’s safe for planning purposes and safe to use. It’s been standardized and agreed upon by nearly every major automaker so automakers don’t have to worry about engineering infrastructure as much as they have to worry about designing next-generation cars. And using both AC and DC current at the same time, it’s becoming a faster way to charge a car, as automakers are now experimenting with 90-kilowatt power sources. With a big enough onboard charger, that could charge a new RAV4 EV to full in less time than it would take to do a round of grocery shopping. But let’s not get ahead of ourselves with technology not yet available.
But then there was Tesla…
Tesla is a bit of an odd case. Its home charger is able to generate as many as 20 kilowatts, which a representative from Toyota’s plug-in supplier Leviton says would force just about anyone to have to have an electrician come in and rewire a whole house. It’s simply more electricity than most houses on a grid could generate safely without major upgrades.
Additionally, Tesla refuses to use SAE J1772 as its standard plug, although it provides an adapter for when drivers are on the go. Interestingly, the upstart automaker also provides the option of plugging in two cords at once, providing up to 62 miles of range in a single hour.
Also in Tesla’s plans for the Model S and other upcoming cars is to build a series of SuperChargers alongside highways for roadtripping. Of course, they’d be only available to Tesla owners because of the proprietary cord design.
SAE J1772 may not be the most efficient, but it’s the most efficient overall charging method and cord design that will accommodate nearly every electric car sold in the U.S. and almost every electric car sold around the world. If every car ran on something different—say one ran on ethanol while another ran on diesel and yet another ran on whatever you could find that would fit into a Mr. Fusion—automakers wouldn’t be able to pin down what technologies would best allow them to make cars most practically. J1772 clears that up, giving automakers an idea around which they can base their technology development. And if the technology keeps improving as quickly as it is, streamlining the world on a single standard might become all the more easy.
CHAdeMO looks like a great option because of its rapid-charging capabilities, but it’s too much wattage to safely install in a house and too limited an infrastructure for an automaker to sign on board with. For the electric car industry to grow, cars will invariably have to become cheaper to produce, and infrastructure—both in homes and at charging stations—will have to be able to handle higher loads. Standardization will play a large role in both happening as electric cars become more common.