I think that in general a 120v 20A receptacle at each parking stall would do most drivers in an office tower - we have at least one in Vancouver here. In a mall or other shorter term parking situation a small set of full J1772 L2 chargers is probably the best solution.
Lawrence > On Nov 8, 2016, at 15:56, ROBERT via EV <[email protected]> wrote: > > Again I must correct myself. I looked back at the J1772 standard and some > past work that I did. An EVSE outputs a 1KHz square wave. The duty cycle of > this wave informs the the vehicle of the maximum amperage that the EVSE can > supply (rated current). The vehicle is responsible for not drawings a > current greater than the EVSE rating. All lower amperage adapters must limit > this duty cycle to the rating of the adapter. As an example. If the EVSE is > rated at 50 amps and the adapter is only rated for 20A, the adapter must > adjust the duty cycle. It is possible to design a 20A adapter with a switch > and a resistor that does not modify the duty cycle from the EVSE. This would > be an unsafe adapter design. These type adapter do exist. You are correct > in stating that no car manufacturer would use this type of design. > > > As happens many times, the discussion in a forum can get side tracked. The > original discussion (I had to look at previous emails) was concerning a large > NEMA plug system vs a large EVSE system for a parking area. I commented that > a NEMA system would works; however, it had some issues. One of the issues > was unsafe adapters usage and another was how does a vehicle with a J1772 > connector know the rating of the NEMA plug. I still stand by these two > issues. Unsafe adapters do exist and there is no way of preventing a person > from using one in an un-monitored parking area. In addition, the vehicle > cannot know the rating of the NEMA receptacle. The adapter can tell the > vehicle the rating of the adapter but not the rating of the NEMA receptacle. > > ________________________________ > From: EV <[email protected]> on behalf of ROBERT via EV > <[email protected]> > Sent: Tuesday, November 8, 2016 2:24 PM > To: Roger Stockton; Electric Vehicle Discussion List > Subject: Re: [EVDL] Cheap L2 charging in parking places: Bolt EV'sIn > Production > > How many of these adapters are approved by the vehicle manufacturer and how > many are UL listed? In addition, how many of these adapters come with a list > of vehicles for which they have been tested and certificated by the UL or the > manufacturer? In addition, I know of companies that are selling adapters > that do not issue a pilot signal (square wave). The adapters only have a > switch that show that a vehicle is connected. I guess I should not have > stated "they are not safe to use". I should have stated that these adapters > have not been shown to be as safe as the J1772 connectors installed by the > vehicle manufacturers. > > > Some car manufacturers like Tesla sell adapters. However, these adapters > should not be used with other vehicles. > > > ________________________________ > From: EV <[email protected]> on behalf of Roger Stockton via EV > <[email protected]> > Sent: Tuesday, November 8, 2016 11:26 AM > To: Electric Vehicle Discussion List > Subject: Re: [EVDL] Cheap L2 charging in parking places: Bolt EV'sIn > Production > > ROBERT via EV wrote: > >> (1) How does a vehicle with a J1772 connector know the rating of the NEMA >> outlet? > > The portable J1772 EVSE charging cord/adapter tells the vehicle via the pilot > signal how much AC current may be drawn. A 120V J1772 cord will almost > certainly tell the vehicle not to draw more than 12A, so that it is safe to > use on any 15A or 20A 120V outlet. I believe that some aftermarket cords may > be available with a 16A pilot signal or the ability for the user to configure > the cord for either 12A or 16A, however, I an unaware of an OEM cord with > this capability. > >> One can buy a J1772 to NEMA >> adapter; however, they are not safe to use. All these adapters "fake out" >> the EVSE and the user must be aware of the limitations. It would not >> surprise me to see these adapters outlawed. > > I'm not sure what sort of adapter you are thinking of. As far as I know, > every OEM that offers an EV with a J1772 charge inlet wither includes or > offers a 120V J1772 "opportunity charge" cord. This cord *is* a proper J1772 > EVSE and not only provides an appropriate pilot signal to the vehicle, but > also does not energise the charging plug until it senses that it is mated > with a J1772 receptacle. > > I can't see how one of these NEMA to J1772 opportunity charge cords can > possibly be *less* safe than an ordinary NEMA extension cord between the > outlet and a charger on the vehicle. > > Cheers, > > Roger. > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > EV -- Electric Vehicle Discussion List - lists.evdl.org > ...<http://lists.evdl.org/listinfo.cgi/ev-evdl.org> > lists.evdl.org > The Electric Vehicle Discussion List is a forum for discussing the current > state of the art and future direction of electric vehicles (EVs). 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