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J1772 2-port load balancing charger

Discussion in 'Charging Standards and Infrastructure' started by hiroshiy, Apr 30, 2017.

  1. hiroshiy

    hiroshiy Supporting Member

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    Hi, I plan to move to a smaller new condo and plan to setup a charging there. Basically the condo will have one flat parking and probably 8 mechanical parkings, with one car temporary space for charging (this space wasn't designed as a charging spot but I'm trying to convince the developer to).

    I think I can use the flat parking so there will be two charging spots there, so I would like to have one 2-port charger like WattZilla Duo.

    The question is, if I have one or two more EV owners to charge, how should I split the electricity cost? Seems WattZilla doesn't have a electricity meter function at all. Would it be better to have two WattZilla Uno and two meters? What do you do to split the cost in condos?
     
  2. RichardD

    RichardD Supporting Member

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    Gentlemans agreement not going to work? What do you anticipate the cost to be per month for both of you to charge?
     
  3. hiroshiy

    hiroshiy Supporting Member

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    I am more than willing to accept gentleman's agreement, but people here tend to be very precise about many things. I will charge like $80 per month and not sure other people. Some people drive only on weekends.
     
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  4. swaltner

    swaltner Member

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  5. hiroshiy

    hiroshiy Supporting Member

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    Thanks, they said they have no idea whether it works in Japan or not. Have you used the credit card option? Typically charging a small amount of money to a credit card costs some extra fees on each transaction. If for example I need to pay $2 per each transaction or pay 10% in credit card processing fees, then that would be difficult to pursuade other EV owners.

    Maybe is it better off having two AC feeds and two meters and one WattZilla Duo, just to meter electricity usage?
     
  6. swaltner

    swaltner Member

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    Sorry, missed the fact that you are in Japan. I don't know if the system would work in Japan.

    I don't know specifics on the Nayax option, but this company looks to specialize in micro-transactions like you get on vending machines. They aren't going to have large fees on transactions that tend to be 50 cents to 1 US dollar. For example, the vending machines at work have similar readers that support credit cards and NFS payments via Apple Pay (and I'm sure other vendors as well). The credit card reader only puts a 10 cent premium on a transaction. That makes the 12 oz can of pop cost 35 cents instead of the cash price of 25 cents.

    I would maybe ping @pox about their experience with the WattZilla and Nayax card readers. They started a thread at Riverton and Lander Wyoming Breadboards Getting 80amp Chargers where they were hosting several of these sites.

    Working on the assumption that the WattZilla unit hasn't strayed too far from the base OpenEVSE source code that they apparently started with, I would assume you get some basic on-board power monitoring with the WattZilla units. The following is the display from my OpenEVSE unit in my garage. Default fields on the display are as follows:

    Status: Ready, Not Connected, Charging, Fault
    Charging Speed: L1 or L2 (120V, 240V) and max amps that the system is configured, or a real-time current meter while charging
    Energy used in current or last charging session - mine is reading 7,546 Wh (7.5 kWh)
    Total energy used - mine is reading 3,166 kWh (about 11,000 miles of driving on the Leaf)

    Be aware that, at least for the stock OpenEVSE units, there isn't a real-time voltage meter. The firmware assumes that the voltage is a steady 120V or 240V. This throws the energy readings off if you're on a commercial circuit with 208V or somewhere else that uses a "non-standard" voltage. I don't know what Japan does for standard voltage. Even with that limitation, I found the energy readings on the OpenEVSE display were very close to the reading from my TED 5000. For example, last month, the TED reported 263 kWh and the OpenEVSE reported 261kWh consumed. It's not "revenue grade", but it seems to work fairly well.

    IMG_1382.jpg
     
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