Prime charging on a timer

Discussion in 'Prime Plug-in Charging' started by IABoy987, May 21, 2020.

  1. jerrymildred

    jerrymildred Senior Member

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    Actually, if there is no schedule at all programmed into the car, it will charge immediately when you plug it in. If there is a scheduled charge, the car will wait for that day and time unless you override it. At least that's the way mine was before I programmed the charging schedule.
     
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  2. Hicksite

    Hicksite Junior Member

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    Ok that’s what I thought, but It’s my understanding that the OP did not have a charge event set up. So the posts stating that no charging event would be triggered by him plugging it in because the default is a timed event seem incorrect to me.
     
  3. IABoy987

    IABoy987 Member

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    Hi Rob,
    So clue me in what advantage will I gain with 240V? The power pack runs hotter (assuming its dual voltage), and I think the big battery is stressed with higher charging voltages and current to achieve 2hour charging. In my work with batteries in the radio factory we were told the lower the charge currents and voltages, the longer life of the internal chemistry.
    In my case being retired we go to bed late and rise late so 5 hours over night is no big deal, if the Prime was being turned around quickly then I could see having 240V line.
    Am I missing something here???
    Thanks
     
  4. Rob43

    Rob43 Senior Member

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    Convenience.


    Rob43
     
  5. mr88cet

    mr88cet Senior Member

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    For example, our Saturday routine (before COVID19 lockdowns) consisted of:
    * A scheduled morning charge,
    * Drive on EV to the rowing club and back,
    * “Charge now” at home,
    * 2.5 hours later, rather than 5.2 hours, after taking a shower, and grabbing some lunch,
    * Drive on EV to the grocery stores we like.
     
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  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Right but if there's no schedule, then the car defaults to "charge now". There isn't a "non-event" situation. That's why I'm confused.

    If all the schedules are OFF (or there aren't any in the first place), then the car will always charge immediately upon plugging in and getting power. So by that logic, if the car gets power in the middle of the night because the outlet timer switched on, in theory, the car should charge.

    Ahh I see. I'm in a unique scenario where I have both but I mostly go without a charging schedule so it always charges immediately for me (convenient for public charging stations). However at home, I will turn on the charging event for the next day if need be (and it varies, so I have different start times and that's why I can't leave them all on at the same time).

    Same. So we're on the same page. Without a charge event, the car will immediately start charging on its own. The question now is if it's plugged into a "dead" outlet so the car never makes the handshake and then the outlet turns on for the first time overnight because of the timer, then it should be the same sequence as if he physically plugged into the 120V side into a live outlet at 2am in the morning.
     
  7. Salamander_King

    Salamander_King Senior Member

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    You are correct that without scheduled event, PRIME will start charging middle of night upon power being supplied by the wall timer as if it was physically plugged into the wall at that time. I have tested this on my previous PRIME and confirmed that charging starts when wall socket is plugged. As long as the timer is rated for continuous 12A and makes good connection, what OP is planing to do would work. But cost more money and insert another piece of element in between the wall outlet and the plug, making it less safe, IMHO.
     
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  8. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Is this prime going to be your last car, or last car garaged at this address?

    Your next car may get a better benefit from 240V service. Might even require it. Same goes for future owners of this home.

    If I needed to bring in the sparkies at all, I'd just have them do the one job for both service types.

    I'm with you on wanting to use an external timer. It's cool that the car has its own built in, but I would prefer the simplicity and accessibility of one on the wall next to the receptacle myself.
     
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  9. jerrymildred

    jerrymildred Senior Member

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    Electronics 101: Current (amps) causes heat. Volts do not. Power is volts times amps, so doubling either doubles power. That's why we can run a 900 HP electric motor at 4,160 volts with about the same size wire (and amps) as we use to run a 100 HP motor at 480 volts. Current is the same, but power increases thanks to the voltage increase. So, as long as the current stays the same, the heat stays the same.

    What happens inside the car is where it gets a little more complicated. If I've made any arithmetic or operational errors here, hopefully one of the guys who really know this stuff will set me straight, but here goes.

    The charger inside the car needs to push over 351 volts into the battery to charge it since that's the battery's nominal voltage. Being fed by 240 provides more power which the charger can use to increase either voltage or amperage to get energy to the battery faster. I doubt that it would increase voltage by very much due to safety factors, so it's probably more current. Even so, the additional current is very small compared to the currents used in driving.

    Keep in mind that if I drive in EV at 60 mph, I'll deplete the battery in well under a half hour. That's four times the rate of energy transfer that you'd get with L2 charging. So, if L2 is bad for the battery, driving the car is REALLY bad. An OBDII adapter and a phone app will show that the car is pulling WAY WAY WAY more than 16 amps from the battery most of the time and pushing almost as much back into the battery when decelerating. I once filled my battery from 10% to 98% going down a mountain in Colorado. It took about 15 minutes. At 98%, the engine started. I suppose that was because the battery got warm and the car stopped charging it.

    If I use 6 kWh in 30 minutes, at 350 volts, that an average of over 34 amps. Lots more than the 12-16A pulled from the wall by the charger. My meter shows that my 16A L2 EVSE is using about 3.8 kW while charging. If there were no losses (and there are plenty of losses), at 351V to the battery, that would only be 10.9A going into the battery. In reality, it's probably under 9A. That about a tenth of what the battery handles while accelerating or braking.

    Oh! And then there's driving in charge mode. That'll charge the battery to 80% in about a half hour. Almost four times faster than L2.

    There is absolutely nothing to fear from L2 other than being able to get back on the road quicker and saving a tiny amount of energy thanks to the shorter time running fans and wasting heat.
     
    #29 jerrymildred, May 22, 2020
    Last edited: May 22, 2020
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  10. john1701a

    john1701a Prius Guru

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    It's actually only twice as fast. The video I filmed (below) made it to 80% (from 14%) in 37 minutes. Looking at the aftermarket gauge, rate is roughly 7.2 kW... which is still quite modest it terms of what can be pushed to lithium batteries for automotive use. Tier-1 for Tesla goes up to 60 kW. The industry is trying to push well past 150 kW... attempting to double that if cost can be properly addressed. So, a sustained 3.6 kW from a L2 is nothing, especially if you let the pack cold soak for a few hours before starting the charge.

     
    #30 john1701a, May 22, 2020
    Last edited: May 22, 2020
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  11. jerrymildred

    jerrymildred Senior Member

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    I was hoping you'd provide one of your cool videos for illustration. (y)(y)
     
  12. john1701a

    john1701a Prius Guru

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    Even nicer is the slew of options available from a Wi-Fi enabled charger. We have 2 JuiceBox Pros. They allow you to set minimum & maximum charges, to set time-of-use scheduling, and to monitor session & lifetime stats.
     
  13. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Beauty is in the eye of the beholder. There's something to be said for a basic mechanical timer where you just move a couple of pegs to set the timing events and spin the wheel to set the clock to the current time.

    No creating user accounts, no ongoing security/credential management, no device pairing, you never get surprised when your new wifi router uses a new standard and won't let your legacy charger connect, or any of that silly stuff. I can't deny that the technology allows a lot of nice incidental features and I'm certain that some users will appreciate them. Maybe even me, whenever I eventually get a pluggy car.

    But sometimes the KISS approach really is the right way, and I like knowing that these cars will still work just fine if this is how the owner wants to use them.
     
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  14. john1701a

    john1701a Prius Guru

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    Then you would be better off with the "set it and forget it" approach from the car itself.

    That mechanical timer (we had that old-school metal box with pegs type in our garage growing up, for the christmas lights) needs to be adjusted if the power ever goes out and twice each year for daylight-savings time.
     
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