SAE International has adopted a new standard that it hopes will help jump-start sales of electric and plug-in electric vehicles. The group, formerly known as the Society of Automotive Engineers, has addressed one of the key weaknesses of electric cars: charging time. The new standard could reduce recharge times to around 20 minutes.
At the present time, manufacturers have adopted various charging systems, which are both expensive and incompatible with other systems. Revised standard SAE J1772, which received formal approval on October 2, is the only worldwide standard for DC charging.
“If you don’t have appropriate standardization,” said Gery Kissel, General Motors’ Technical Specialist and Chair of the SAE J1772 Task Force, “you’re going to see continued fragmentation in the industry. That will lead to, I think, great confusion in the market and perhaps reduce customers’ appetite for this type of technology. Standardization really helps anchor things.”
The centerpiece of the new standard, and the key to rapid charging, is the “Combo Connector.” The former version of J1772, adopted in 2010, contained the specifications of the basic J1772 Connector used for AC recharging at comparatively low levels (AC Level 1 for 120-Volt charging and AC Level 2 for 240-Volt charging). The J1772 connector is compatible with current Chevrolet Volt, Mitsubishi i and Nissan Leaf automobiles.
The revised standard calls for the addition of two extra pins to the basic connector for the optional delivery of direct current for fast charging. This is the Combo Connector shown in the photo above. The new plug is not compatible with any electric vehicles or plug-in hybrids on the market today, but it can be added to future cars, allowing them to use either the standard basic connector or the Combo Connector.
While SAE calls J1772 the only worldwide standard, there are other systems in use such as the CHAdeMO protocol used by Japanese manufacturers. The Leaf and i actually have two vehicle receptacles: one for the basis J1772 connector and one for the CHAdeMO connector.
According to Kissel, Europe is behind the U.S. in the pace of standardization. The European Community uses various IEC/ISO standards to approximate the same end result as the single J1772. In addition, European connectors vary from their U.S. counterparts in having two extra pins to accommodate the three-phase electrical system (the U.S. uses single-phase AC power) but the communications and control architecture is identical because the regions cooperated on a single combo charging system approach.
China uses a system that is unique to that market.
The new standard comes with a bonus: The latest version of J1772 allows digital communications over one of the pins in the legacy portion of the combo connector. The benefit is larger bandwidth allowing large files, like movies, to be downloaded quickly.