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| The prototype J1772 unit. Click to enlarge. |
Coulomb Technologies (earlier post) is showcasing prototypes of Level 2 high power networked charging stations that will comply with the new SAE J1772 Electric Vehicle Conductive Charge Coupler Specification at the EDTA conference 2-4 December in Washington, DC.
SAE has been making modifications to the older J1772 REV NOV 2001 standard, moving toward a smaller (and less expensive) coupler made by Yazaki to replace the former Avcon connector. The new SAE J1772 standard is being finalized now, and may be balloted by the first quarter of 2009.
The J1772 standard specifies a specific 5-pin plug (two power, two signal, one ground) for single-phase supply up to 80A.
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| Preliminary vehicle inlet design. Click to enlarge. | Preliminary vehicle coupler design. Click to enlarge. |
The industry in the US will standardize on the J1772 coupler; because the plug on the car can be a costly item in moderate volumes, standardization is the preferred route for the industry. The California Air Resources Board (ARB), for example, which incorporates the older J1772 standard in its recharging requirements, will update the requirements to the new standard.
The connector may also become the standard in Japan, where the SAE and the Japanese standard body are making good cooperation. Although a proposal has been made to incorporate the SAE connector interface in IEC standards although Italy and Germany are proposing alternative connectors. (Design for single-phase power is problematic for countries where 3-phase is also used, notes Cyriacus Bleijs, Chairman IEC TC69.)
In an October update on the J1772 process to an EPRI infrastructure working group for plug-in hybrids (PHEVs), GM’s Gery Kissel said that due to potential arcing damage, the J1772 Task Force is recommending the coupler design for AC Level 1 and 2 charging only. The AC level 1 definition was changed to 120 VAC, single-phase, 20A to be consistent with the NEC. A Level 3 (fast charge) working group has been created, chaired by Dave Francis of AeroVironment.
In a July draft of the new EV charging requirements, ARB staff noted that:
This new Yazaki coupler will, however, be able to deliver much more than the former Level II power limit (6.6 kW), perhaps as much as 16-19 kW. This medium power capability is necessary in order to obtain reasonable charge times with upcoming long-range BEVs. Tesla Motors will be shipping their Roadster in 2008 with a 52 kWhr battery. With the former Level II charge limits of 6.6 kW, charge times for a 52 kWhr battery would become unreasonably long, perhaps as much as 7-8 hours. This charge time duration would extend beyond preferred late-evening low-cost Utility rate schedules, while a medium-power 3-4 hour charge could be scheduled to “fit” better into these upcoming schedules.
It is assumed that high power capable EVs (50+ kW) would now make use of a separate on-vehicle higher-power inlet standard that is yet to be developed. Overall, the attractiveness of all PHEVs and BEVs making use of an consistent, almost worldwide J1772-Yazaki-based low-to-medium power connection standard more than outweighs the loss of potential high power capability with the former Avcon connector. The need for and attractiveness of higher “fast charge” power capability for EVs is not yet proven to be necessary to market BEVs.
Resources
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SAE J1772 Task Force Update for IWC (Infrastructure Working Council) PHEV (June 2008)
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Proposed Test Procedure Modifications to Address Plug In Hybrid Electric Vehicles (ARB)
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Minutes of the October PHEVWG Meeting
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Charging infrastructure for electric vehicles and PHEVs (Cyriacus Bleijs, Chairman IEC TC69)
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ARB July 2008 draft of EV Charging Requirements