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Smart current limiting switch

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  • 12-05-2021 1:58pm
    #1
    SD_DRACULA
    Registered Users Posts: 2,227 ✭✭✭


    Trying to make my current dumb car charger smart (no I don't want a zappi for various reasons) and I need something with wifi control that allows me to remotely change the amount of amps/current that is going to the charger.

    Something similar to the Shelly 1 which I am currently using to toggle on/off my external socket and granny cable combo based on live excess solar, except this would need to control the amount of amps going to the charger instead.

    Any idea if such a device exists and what it is called? Searched online but did not find anything just yet
    16amps limit would be fine since this the max draw of the car.


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    #2
    graememk
    Moderators, Home & Garden Moderators Posts: 5,788 Mod ✭✭✭✭graememk


    SD_DRACULA wrote: »
    Trying to make my current dumb car charger smart (no I don't want a zappi for various reasons) and I need something with wifi control that allows me to remotely change the amount of amps/current that is going to the charger.

    Something similar to the Shelly 1 which I am currently using to toggle on/off my external socket and granny cable combo based on live excess solar, except this would need to control the amount of amps going to the charger instead.

    Any idea if such a device exists and what it is called? Searched online but did not find anything just yet
    16amps limit would be fine since this the max draw of the car.

    The charge point, doesn't "throttle" or limit the current going to the car

    It just tells the car how much current to draw. Inside the zappi or any other smart/solar compatible charge point is still only a contactor. The car is told how much it can draw, and should only draw that amount.

    An openEVSE/EmonEVSE could be suitable but that needs a MQTT feed of your excess amount (you must have access to a value as you are already switching on and off the socket)


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    #3
    SD_DRACULA
    Registered Users Posts: 2,227 ✭✭✭SD_DRACULA


    So I can also hook up a contactor relay to the breaker of the wall charger which can be controlled by the Shelly EM but that will only give me toggle on/off capability of it and will still draw 16a when on. If you could get a contactor relay that can control current it would be spot on.

    openEVSE/EmonEVSE is the same replacing it with the zappi so I want to avoid removing my current charger altogether.

    The search goes on...


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    #4
    graememk
    Moderators, Home & Garden Moderators Posts: 5,788 Mod ✭✭✭✭graememk


    I'm open to correction here, but I don't think what your asking for is possible.

    Resistors, reduce current, I = V/R

    But any current the resistor takes, has to be got rid of. (Heat)
    So the car is trying to pull 16 amps
    If your resistor took 8 amps, the car will only get 8

    But that 8 amps is dumped out as heat. And you will still be drawing 16 amps from the fuseboard.

    It has to be done at the car end. The car must choose to take less power.

    The immersion diverters get around this by modifying the voltage (it's a bit more complicated than that but that's the general of it). The immersion still pulls it's full amperage but at half voltage it only draws half the power.


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    #5
    SD_DRACULA
    Registered Users Posts: 2,227 ✭✭✭SD_DRACULA


    Well I had a closer look at openEVSE and that can do it so it is possible for sure, they even sell a kit with just the guts.
    The car can set multiple values from 6 to 16amps when using granny cable (maxes out at 10a on that) but I find it stupid that when connecting the wall charger always draws 16a, which makes me wonder what's the point of 11-16a?


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    #6
    graememk
    Moderators, Home & Garden Moderators Posts: 5,788 Mod ✭✭✭✭graememk


    SD_DRACULA wrote: »
    Well I had a closer look at openEVSE and that can do it so it is possible for sure, they even sell a kit with just the guts.
    The car can set multiple values from 6 to 16amps when using granny cable (maxes out at 10a on that) but I find it stupid that when connecting the wall charger always draws 16a, which makes me wonder what's the point of 11-16a?

    Because the openEvse is a full charge point, like the zappi. It does the communication with the car.


    How come your wall charge point only supplies 16a not 32?


    On my car I only have 3 levels min med max, every car is different but my EmonEvse can track the solar really well.


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    #7
    KCross
    Registered Users Posts: 12,070 ✭✭✭✭KCross


    SD_DRACULA wrote: »
    Trying to make my current dumb car charger smart (no I don't want a zappi for various reasons) and I need something with wifi control that allows me to remotely change the amount of amps/current that is going to the charger.

    What dumb charge point do you have right now?

    You'd need the ability to program the controller in the charge point so that you tell the controller what current you want and it then negotiates that with the car.

    Most dumb charge points dont allow you to access the controller so you'd probably be looking at replacing that with a "smart" one.

    Something like the Viridian controller (scroll to the end)
    https://viridianev.co.uk/products

    If your existing unit is a Rolec I know the Viridian slots in nicely in terms of fit and wiring. Not sure it gives you everything you need in terms of Wifi, app or the level of control you need but its worth a read of the manual and decide for yourself.

    It would be alot of hassle though, I'd say. Would be easier, imo, to sell your charge point and buy a "proper" one that has ongoing support.... unless you like the challenge! ;)


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    #8
    SD_DRACULA
    Registered Users Posts: 2,227 ✭✭✭SD_DRACULA


    graememk wrote: »
    Because the openEvse is a full charge point, like the zappi. It does the communication with the car.


    How come your wall charge point only supplies 16a not 32?


    On my car I only have 3 levels min med max, every car is different but my EmonEvse can track the solar really well.

    It is 32a but the car can only pull 16
    KCross wrote: »
    What dumb charge point do you have right now?

    You'd need the ability to program the controller in the charge point so that you tell the controller what current you want and it then negotiates that with the car.

    Most dumb charge points dont allow you to access the controller so you'd probably be looking at replacing that with a "smart" one.

    Something like the Viridian controller (scroll to the end)
    https://viridianev.co.uk/products

    If your existing unit is a Rolec I know the Viridian slots in nicely in terms of fit and wiring. Not sure it gives you everything you need in terms of Wifi, app or the level of control you need but its worth a read of the manual and decide for yourself.

    It would be alot of hassle though, I'd say. Would be easier, imo, to sell your charge point and buy a "proper" one that has ongoing support.... unless you like the challenge! ;)

    This one, https://www.ablmobility.de/en/products/emh1.php

    Yeah it looks like replacement is the only option as there is no "off the shelf" solution that is plug and play.


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    #9
    KCross
    Registered Users Posts: 12,070 ✭✭✭✭KCross


    SD_DRACULA wrote: »
    It is 32a but the car can only pull 16



    This one, https://www.ablmobility.de/en/products/emh1.php

    Yeah it looks like replacement is the only option as there is no "off the shelf" solution that is plug and play.

    The link you posted says...
    “Adjustable charging current via configuration software and CONFCAB
    The charging current range can be selected in 1 A increments via software”

    Have you checked that out? Maybe that’s just for initial setup or maybe it would allow continuous changing?


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    #10
    SD_DRACULA
    Registered Users Posts: 2,227 ✭✭✭SD_DRACULA


    Yup saw that too but couldn't find anything else about it - I also had this installed like 3 years ago and while it is the same model number maybe things have changed in the meantime.

    https://ecoharmony.co.uk/collections/ev-plugs-sockets-and-parts/products/viridianev-scc seems to be exactly what I need but remains to be seen if it can be integrated with other chargers or just their own (more than likely this)


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    #11
    KCross
    Registered Users Posts: 12,070 ✭✭✭✭KCross


    SD_DRACULA wrote: »

    https://ecoharmony.co.uk/collections/ev-plugs-sockets-and-parts/products/viridianev-scc seems to be exactly what I need but remains to be seen if it can be integrated with other chargers or just their own (more than likely this)

    That’s the viridian I linked above. Easily retrofits to a rolec but not sure what it would be like in yours.


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    #12
    SD_DRACULA
    Registered Users Posts: 2,227 ✭✭✭SD_DRACULA


    KCross wrote: »
    That’s the viridian I linked above. Easily retrofits to a rolec but not sure what it would be like in yours.

    If I could throw that into my consumer unit and hook it up to the existing rcbo of the charger and can then control the current going to it, that would do it.


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    #13
    graememk
    Moderators, Home & Garden Moderators Posts: 5,788 Mod ✭✭✭✭graememk


    SD_DRACULA wrote: »
    If I could throw that into my consumer unit and hook it up to the existing rcbo of the charger and can then control the current going to it, that would do it.

    It has to go into the charge point, that needs to communicate directly with the car.

    It's the car that controls the current going to it, the charge point just tells it the max it can take.


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    #14
    SD_DRACULA
    Registered Users Posts: 2,227 ✭✭✭SD_DRACULA


    graememk wrote: »
    It has to go into the charge point, that needs to communicate directly with the car.

    It's the car that controls the current going to it, the charge point just tells it the max it can take.

    Ok so not so simple.
    I'll reach out to the ABL folk and see what they're talking about with the controllable current bit


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    #15
    slave1
    Moderators, Sports Moderators Posts: 18,697 Mod ✭✭✭✭slave1


    SD_DRACULA wrote: »
    Trying to make my current dumb car charger smart (no I don't want a zappi for various reasons) and I need something with wifi control that allows me to remotely change the amount of amps/current that is going to the charger.

    Something similar to the Shelly 1 which I am currently using to toggle on/off my external socket and granny cable combo based on live excess solar, except this would need to control the amount of amps going to the charger instead.

    Any idea if such a device exists and what it is called? Searched online but did not find anything just yet
    16amps limit would be fine since this the max draw of the car.

    Just so you are aware there are cars out there and also cables that will restrict the amperage, you can adjust Teslas for a start and Bjorn had an adjustable charge cable but not sure was that remotely controlled...

    My stuff for sale on Adverts inc. outdoor furniture, roof box and EDDI

    My Active Ads (adverts.ie)



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    #16
    SD_DRACULA
    Registered Users Posts: 2,227 ✭✭✭SD_DRACULA


    Yeah I actually found a "smart" cable alright, something ohm, but it costs as much as a wall charger so might just go for the emonEVSE eventually since it can use existing mqtt data from my home automation setup


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    #17
    graememk
    Moderators, Home & Garden Moderators Posts: 5,788 Mod ✭✭✭✭graememk


    SD_DRACULA wrote: »
    Yeah I actually found a "smart" cable alright, something ohm, but it costs as much as a wall charger so might just go for the emonEVSE eventually since it can use existing mqtt data from my home automation setup

    What I can actually do is feed it an adjusted value, on good days to slow the battery charge, to 1-2 kw and let the car get the rest.


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