Possible Adapter Connections between J1772 and J3068 AC6 (limited application)
While EV charging stations are much more common today than they were when I took my first 1000 mile EV trip in 2010 (when there were zero public charging stations), there are still many areas where charging station availability is inadequate for reliable long distance travel in EVs from legacy automobile manufacturers.
For this reason, adapters are appealing to many EV drivers, since electricity is available almost everywhere and the right adapters allow you to charge your EV almost anywhere, albeit slowly. Many voices point out that adapters add risk. This is true, so adapters are to be avoided whenever possible. But in the global sense, driving “vacuum tube” powered cars (that is, fossil fuel powered cars that draw a vacuum in the cylinder during the intake stroke) is far more dangerous to our grandchildren.
When a driver of a “vacuum-tube” powered car is concerned about running out of fuel, they might carry a safety “gas-can”. This safety can should meet safety requirements from UL, OSHA, NFPA, and perhaps other regulations. The can might have a spring loaded, self sealing lid with a pressure vent, a flame arrestor under the opening, be color coded for the fuel it contains, etc. And above all, it should be used as infrequently as possible. If gas cans were simply outlawed and not regulated, then people who need this functionality might use an old milk jug instead. I am serious, I know people who have nearly killed themselves by transporting gas in an old plastic milk jug.
This is similar to the use-case for charging adapters with “transistor powered” EVs. Adapters should be regulated and used rarely, but not prohibited because prohibition will increase the use of less safe adapters.
I carry at least one adapter whenever I take a long trip. Fortunately, I have not needed to use them in years and hope I never have to again. But the “safety net” provided by an adapter is still compelling in many situations, since it can provide reassurance that you will not get stranded even if a charging station that you planned to use is broken.
Early in the development of J3068 we considered the transition period where J3068 AC charging stations would be relatively rare, and J1772 stations (although usually offering much less power) might provide a useful “safety-net” in some situations. Therefore, an example was given of an adapter application in an early draft of J3068, which was deleted prior to publication due to the general controversy around adapters.
Note that the California Code of Regulations Title 13 section 1962.3 (c) (2) states that adapters are REQUIRED in certain applications for participation in ZEV credit markets, as follows (see page 239 of the printed version of the above link, page 247 of the PDF version):
Title 13 CCR 1962.3 (c) (2) A manufacturer may apply to the Executive Officer for approval to use an alternative to the AC inlet described in subdivision (c)(1), provided that the following conditions are met:
(A) each vehicle is supplied with a rigid adaptor that would enable the vehicle to meet all of the remaining system and on-board charger requirements described in subdivision (c)(1); and
(B) the rigid adaptor and alternative inlet must be tested and approved by a Nationally Recognized Testing Laboratory (NRTL).
From what I have seen published in fan blogs about the brand mix of the plug-in fleet in North America, it appears likely that the majority of plug-in EVs on our roads are delivered to customers with the above required adapters. These adapters are safety certified to Underwriters Laboratories requirements. IEC standards in Europe also permit adapters in certain circumstances (adapters must be supplied by the EV manufacturer, etc.). Lastly, the European “Case B” cables with a three phase plug on one end and a single phase connector on the other end are essentially, flexible-adapters. And they are ubiquitous among “transistor powered” cars in Europe.
With all of that said, here is the adapter example that never made it into J3068:
5.7.1 Charging an EV Type J3068 AC6 LIN/PWM from a J1772 SE, informative
Certain three-phase EVs type J3068 AC6 LIN/PWM can be charged from a J1772 EVSE which supplies 208-240 V, max 80A, max 19.2kW, under conditions such as the following:
- The EV utilizes three separate single-phase Chargers arranged in a Wye load topology.
- The EV implements PWM-CP. See Section 6.2.3.
- An adapter is used between the J1772 Connector and the J3068 Inlet with internal connections as shown in the figure at the top of this page. Note that adapters are discouraged and are for infrequent use only.
- The EV Proximity Detection circuit is able to detect the difference between a J1772 Connector (connected via the adapter) and a J3068 AC6 Connector, and limits the charging current accordingly, particularly on the neutral line. See 7.2.2.
5.7.1.1 Adapters shall be rated for maximum current allowed by J1772, as there is no way to detect adapter current rating distinctly.
7.2.2 Proximity Detection When Using an Adapter from J1772 SE to J3068 EV
If an adapter is used between a J1772 Connector and a J3068 Inlet, the adapter may connect power to all three-phases of the EV Inlet. See Figure at the top of this page.
7.2.2.1 The J1772 Connector proximity circuit shall be passed through the adapter.
7.2.2.2 If PWM is supported, the EV shall detect the J1772 values of the resistors R6 and R7 (see Table 13, lines 6 and 8) and limit the sum of the currents drawn by all phases to the received “allowed current” value, as opposed to the usual three-phase case where “allowed current” is applied to each phase leg individually.
For example, if the EV draws current on all three phases, each phase is limited to 1/3 of the “allowed current” value when supplied through a J1772 adapter. If the EV chooses to draw current from only one phase when it detects a J1772 Prox (as in lines 6 and 8 of Table 13), it allows the full “allowed current” value to be drawn from one phase and zero current from the other phases. Other proportions are possible, usually to optimize Charger efficiency.
Note that this configuration is useful for heavy duty applications that require power on all three phases to charge. Unlike passenger cars which often charge from only one phase, single-phase charging is sometimes not supported in heavy duty applications. Similarly, heavy duty applications sometimes do not support 120 VAC charging either.
Here is an example of an adapter from J1772 to J3068 that probably has only one phase connected, and thus would not work for the example above. It is also not rated for 80 amps and thus would not be allowed by the above requirements.
