Unplug charging cable when not in use?

Discussion in 'Prime Plug-in Charging' started by draheim, Mar 23, 2018.

  1. draheim

    draheim Member

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    Hello all, last week I bought a 2018 Prius Prime Plus, loving it so far. I haven't used a thimble of gas and I'm currently at 84 MPG. :) Traded in my 2010 Prius in the process, that was a great car too but the Prime was an upgrade I've been waiting for for a long time.

    I set up my "charging station" in the garage last night, involving a 12/3, 125V extension cord out of a ceiling outlet (the outlet also powers the garage door) running along the ceiling and down a post in the middle of the garage, with clips every foot or so to hold the cord in place. Also set up the charging timer on the car so it charges up overnight and is ready to go at 7:30 a.m. (though I'll likely only need to charge it every 2 or 3 days using this function).

    Question is (and I tried to find an answer here before posting), should I be disconnecting the charging cable from the extension cord when I'm not actively charging the car? The manual (p112) says this needs to be done only when the charging cable is not in use for extended periods, but are there any advantages to disconnecting? Disadvantages? I'm inclined to leave it plugged in only because knowing myself, I'm likely to forget to disconnect it half the time anyway. But if there are clear reasons to get in the habit of doing this, I'd like to know early.
     
  2. bisco

    bisco cookie crumbler

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    the only reason to disconnect would be the minute amount of energy the cable is drawing when not in use.
     
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  3. zigzag

    zigzag New Member

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    There is one other reason and that is that there is a small chance that the cable might get damaged while it is plugged in. If someone did some damage leaving it unplugged is safer. Having said that, I leave mine plugged in all the time.
     
  4. Toyotacarguy

    Toyotacarguy New Member

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    Does anyone know exactly how much energy the charging cable and interrupting device consumes when not in use?
     
  5. jerrymildred

    jerrymildred Senior Member

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    Welcome! Congrats on the new Prime. My L2 EVSE is pulling 1.3 watts right now while waiting to start charging in the morning. That's so little current at 240V that it's showing 0.00A. (By my calculations it's actually about 0.00542 amps.) My OEM 120V EVSE shows about 0.019A on my clamp-on meter.

    As to the original question, which seems to have died on the vine, the biggest reason to unplug the EVSE when not in use is to eliminate the possibility of lightning damage.
     
  6. road2cycle

    road2cycle Junior Member

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    Thanks for posting the EVSE power draw when it’s in “standby” mode. I was trying to determine if it’s worth the hassle of unplugging it after each charge to save a bit of electricity. It comes out to about 40 cents per month where I live, so in my opinion not worth it unless a lightning storm is lurking.
     
  7. Salamander_King

    Salamander_King Senior Member

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    If you keep the charging cable connected to the wall, then it does cost wasted electricity a bit. But you should unplug the cable from the car as soon as the charge is complete. Keeping the charging cable after the charge is complete will drain the 12v battery. If it is a few days, it is not a big deal on a healthy 12v battery, but if you keep it plugged in for weeks or months, it can drain the 12v battery dead. Also if the 12v battery is getting old and weak, even a few days of keeping the charging cable connected can cause the 12v battery drain to the point of not being able to start the car.

    Screenshot 2020-05-10 at 3.24.40 PM.png
     
    #7 Salamander_King, Jan 24, 2021
    Last edited: Jan 24, 2021
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  8. road2cycle

    road2cycle Junior Member

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    Thanks for the info. I am planning to unplug the car side of the EVSE from
    the Prime shortly after charging is completed. Good to know not doing so can drain the 12V battery.

    I should have clarified my above post was for the wall outlet side of the EVSE.
     
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  9. Salamander_King

    Salamander_King Senior Member

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    Yeah, I missed that when I first read the comment. Then realized it was on the wall side. Yes, I have kept the EVSE plugged into the wall socket for over three years, no problem.
     
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  10. Old Bear

    Old Bear Senior Member

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    That sounds about right.

    However, if your EVSE is connected to a power source (plugged into a wall outlet) and plugged into the car, you cannot put the Prime in drive. The Prime knows it's plugged in and keeps you from driving off with the cable connected.

    (You probably would be surprised to learn how many people have had to pay damages to a gas station for driving off with the gas pump nozzle still inserted into their cars. Sounds really stupid but it happens and can be dangerous, too.)

    What I don't know (and someone can check this out) is whether you can drive off with your EVSE dragging behind your car is the EVSE is not plugged into the wall. I know that you'll get a "charging port door open" indicator on your instrument panel, but I don't know if the Prime recognizes the presence of a charging cable with no voltage or signal from the EVSE present.
     
  11. road2cycle

    road2cycle Junior Member

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    I’m guessing it happens more often than not in the climate extremes where folks get back into the vehicle while the tank is filling up.

    If nobody has tried what you mentioned I’ll have to see if the Prime can be shifted into gear when:
    1) Charge port door is open without EVSE inserted.
    2) Charge port door is open and unpowered EVSE is connected.

    If it shifts into gear I’ll make the assumption it can be driven in either of the above two conditions.
     
  12. Old Bear

    Old Bear Senior Member

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    You definitely can drive the Prime with the charge port door open. The instrument cluster will display a "charging port door open" message. This can happen if you do not fully close and latch the charge port door -- something I've failed to do on several occasions when in a hurry and not carefully pushing the door all the way closed.

    However, I do not know how the Prime would respond to an unpowered EVSE left plugged in. There would be no electrical signal to alert the Prime but it may sense the mechanical latch on the J1772 connector. Let me know if you test this out -- just don't peel out of your garage at full throttle. ;)
     
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  13. road2cycle

    road2cycle Junior Member

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    I just tried both. As you mentioned you can put the Prime in gear with the charger port door open. But the Prime is smart enough to know an unpowered EVSE is plugged in and will not go into gear. Instead you get a warning message that the charging cable is plugged in.
     
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