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AC charging points technical discussion

  • 25-07-2020 2:21pm
    #1
    Registered Users Posts: 3,177 ✭✭✭ Kramer


    Dempsey wrote: »
    If the car is set to max then the charger must be throttling to 16A

    If you are referring to the home charge point as the "charger", then no, it can't throttle. Charging speed/current is determined by the car &/or cable.

    All the charge point & cable do is signal the car's OBC what it can handle, 16a/32a etc. The actual current pulled is then determined by the car's OBC.

    Home charge points are basically just dumb on/off switches & referring to them as chargers just allows manufacturers & installers to fleece unsuspecting, new EV owners.

    There is a simple resistor in the cable/plug which signals its current handling capacity.


Comments

  • Registered Users Posts: 20,553 ✭✭✭✭ Dempsey


    Kramer wrote: »
    If you are referring to the home charge point as the "charger", then no, it can't throttle. Charging speed/current is determined by the car &/or cable.

    All the charge point & cable do is signal the car's OBC what it can handle, 16a/32a etc. The actual current pulled is then determined by the car's OBC.

    Home charge points are basically just dumb on/off switches & referring to them as chargers just allows manufacturers & installers to fleece unsuspecting, new EV owners.

    There is a simple resistor in the cable/plug which signals its current handling capacity.

    It depends on the charge point installed. Thats why i asked

    On the one i have, i can set the maximum current that any car can draw. I can set the time schedule for when power can be drawn from the point and i can set session limits in kwh's. Probably has a few other tricks that i dont use too.

    You might have a dumb one, doesnt mean everyone else has the same


  • Registered Users Posts: 2,685 ✭✭✭ graememk


    Kramer wrote: »
    If you are referring to the home charge point as the "charger", then no, it can't throttle. Charging speed/current is determined by the car &/or cable.

    All the charge point & cable do is signal the car's OBC what it can handle, 16a/32a etc. The actual current pulled is then determined by the car's OBC.

    Home charge points are basically just dumb on/off switches & referring to them as chargers just allows manufacturers & installers to fleece unsuspecting, new EV owners.

    There is a simple resistor in the cable/plug which signals its current handling capacity.

    Some of the smart ones can vary the output "supplied" by telling the car it can only supply x amount of power, but like you said it's the car in control. I actually think the cheap rolec qubec or whatever it's called has a knob for current selection.

    Volts are given, amps are taken.


  • Registered Users Posts: 3,177 ✭✭✭ Kramer


    Dempsey wrote: »
    You might have a dumb one, doesnt mean everyone else has the same

    No need to have a go at me just because I can't afford an all singing, all dancing, super dooper smart "charger". My dumb charge unit charges my car, it's what I could afford & electricity is electricity :D.
    graememk wrote: »
    Some of the smart ones can vary the output "supplied" by telling the car it can only supply x amount of power, but like you said it's the car in control.

    That's exactly what I was trying, unsuccessfully, to say. The smartest of charge points do the same as a cheap, dumb charge point, in terms of charging a car. They either supply power, or they don't.

    I agree, some units have wifi, timers, rfid access, fancy screens & sensing etc. & cost accordingly, but these are all ancillary functions, if one needs, wants or indeed, can afford them :pac:.


  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    Kramer wrote: »
    That's exactly what I was trying, unsuccessfully, to say. The smartest of charge points do the same as a cheap, dumb charge point, in terms of charging a car. They either supply power, or they don't.

    Not quite. Some smart ones can vary the power delivered by telling the car a different max rate it is willing to supply. The car then reacts and pulls that lower/higher power accordingly.

    Primarily used for those with Solar PV integration.


  • Registered Users Posts: 3,177 ✭✭✭ Kramer


    KCross wrote: »
    Some smart ones can vary the power delivered by telling the car a different max rate it is willing to supply. The car then reacts and pulls that lower/higher power accordingly.

    That's exactly what I said though. A charge point isn't a charger, that's in the car. Thus it can only supply the power, either on or off. It can signal the car to pull less current, but the car ultimately varies the rate.

    Probably splitting hairs but IMO, referring to these home charge points as chargers infers they are something they are not. Consequently, installers & manufacturers are charging over the odds.

    Hope the poster gets sorted anyway :).


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  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    Kramer wrote: »
    That's exactly what I said though. A charge point isn't a charger, that's in the car. Thus it can only supply the power, either on or off. It can signal the car to pull less current, but the car ultimately varies the rate.
    .

    You said the charge point can’t throttle and the car decides the current. That’s not always true. The smart charge points can determine it too in real-time in the same way the car does.

    The car can’t ask for more than it’s allowed and the charge point can’t give more than the car asks for but they can both throttle and change the current up/down.


  • Registered Users Posts: 3,177 ✭✭✭ Kramer


    KCross wrote: »
    You said the charge point can’t throttle and the car decides the current. That’s not always true.

    It is always true though :P.
    KCross wrote: »
    The car can’t ask for more than it’s allowed and the charge point can’t give more than the car asks for but they can both throttle and change the current up/down.

    Again, splitting hairs, but can the charge point send less than 32a if the car requests it & the cable is capable of 32a?

    No, it can't.

    It either makes or breaks the contactor. Once the contactor is closed, full power is available. It can't then throttle or reduce the current, only the car can.

    The car can be told what to draw by the charge point, but it's the car's on board charger that ultimately determines what to pull, in terms of amps.

    I think you know that but are being deliberately argumentative - or I'm projecting, I don't know which :P.

    Again, best of luck to the poster with the slow charging.


  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    Kramer wrote: »
    Again, splitting hairs, but can the charge point send less than 32a if the car requests it & the cable is capable of 32a?

    No, it can't.

    Yes, it can. Thats what Im trying to say to you.
    Kramer wrote: »
    It either makes or breaks the contactor. Once the contactor is closed, full power is available. It can't then throttle or reduce the current, only the car can.

    Incorrect.


    If your only point is that the charger is in the car, not in the charge point then fine but its not true to say that the charge point cant throttle. They can, at least some can.


  • Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 6,070 Mod ✭✭✭✭ liamog


    Mod Note: Moved from the e-Golf thread


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