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Need to keep plugged in in cold weather?

Discussion in 'Prime Main Forum (2017-2022)' started by eegah, Nov 21, 2017.

  1. eegah

    eegah Member

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    I was wondering if the Prime needs to be kept plugged in in really cold weather to protect the longevity of the batteries. Sorry to keep bringing up my Volt (heresy!), but it actually keeps the batteries from getting too cold if the car is plugged in and I was wondering if the Prime did something similar.
     
    #1 eegah, Nov 21, 2017
  2. eegah

    eegah Member

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    Ok, to answer my own question: yes. The "Traction Battery Heater" setting should be on, and the current set at MAX (not 8A). According to this guy's results, the heater won't come on with the 8A setting:

    No battery warmer on my Prime | Page 2 | PriusChat

    So, I need to get an electrician to either (A) ground-ify my garage 120V plug for the level 1 charger, or (B) install a second level 2 charger (I already have one for my Volt). Luckily, I had some foresight and the 240V line can handle 40A, so it can handle two level 2's. I'll probably choose option (A), though.
     
    #2 eegah, Nov 21, 2017
  3. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    The other advantage to leaving it plugged in is even if it's done charging, you can press the "A/C Hold" button on your key fob and it will warm up your interior based on your last heat settings for up to 10 minutes. If it's plugged in, it used the house current to do the heating. Do this 10 minutes before you leave. It's really nice and save your EV range after you leave.
     
    #3 Mark57, Nov 22, 2017
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  4. Deleted member 111882

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    I didn't see any such provision, and I don't have a place to plug in my car at my apartment. So, when it goes down to -20F around here, it says outside unplugged. According to the manual on page 92, the car may not be able to start if the outside temperature is below -22F. So, as long as it's not that cold, I do not worry about battery longevity or protection from the elements.
     
    #4 Deleted member 111882, Nov 22, 2017
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  5. jerrymildred

    jerrymildred Senior Member

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    While there may be certain advantages to leaving it plugged in under certain circumstances, there is no need to plug it in unless you want to charge it. If you had to plug it in to protect it in cold weather, I doubt that anyone in the north would buy one. What if you're driving from Bismark to Boise in the winter and stop for the night in a place where you can't plug it in? That would be unacceptable.
     
    #5 jerrymildred, Nov 22, 2017
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  6. eegah

    eegah Member

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    It's my understanding that long-term, repeated exposure to very cold temperatures hurts the longevity of the batteries (I think it was in the Volt manual). I doubt that occasional exposure is a problem.
     
    #6 eegah, Nov 22, 2017
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  7. Tideland Prius

    Tideland Prius Moderator of the North
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    That is confirmed? That it'll bypass the battery and use AC power directly? I know that is how it's supposed to work but I thought I read somewhere on PC that someone was using climate prep and that was supposed to use wall power too but it ended up using the battery power (and i guess the software should've topped it up but the owner came into the garage and was ready to leave by then).
     
    #7 Tideland Prius, Nov 22, 2017
  8. jerrymildred

    jerrymildred Senior Member

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    Never heard of such a thing. I can't find anything making that claim after a half hour of googling. Please document this. Cold will affect the battery's ability to quickly store or provide power while it's cold, but not its lifespan. There is no liquid in a Lithium battery to freeze. What will shorten its lifespan is storing it repeatedly fully charged or discharged for long periods. Which contraindicates keeping it charged just because it's cold outside. Heat, on the other hand, is hard on batteries.
     
    #8 jerrymildred, Nov 22, 2017
  9. eegah

    eegah Member

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    I'm having a hard time figuring out where I got this impression. Here are the only related statements that I could find in my Volt manual:

    Keep the vehicle plugged in, even when fully charged, to keep the battery temperature ready for the next drive. This is important when outside temperatures are extremely hot or cold.

    Parking the vehicle in extreme cold for several days without the charge cord connected may cause the electric drive unit to be locked in P (Park) until the propulsion system has warmed sufficiently.

    In some ways, a long-term effect on the batteries doesn't really make sense. If it was the case, wouldn't all hybrids require being plugged in in cold weather? I hope you are correct, as I would prefer it not be the case.

    Perhaps the best argument for keeping it plugged in is that remote pre-start AC will be powered from the home electrical system instead of the batteries. I know this is the case for the Volt, but it sounds like there is some uncertainty about whether it happens in the Prime. It seems like doing the remote start while plugged in with the batteries completely drained would answer this question. I may try that tomorrow.
     
    #9 eegah, Nov 22, 2017
  10. Tideland Prius

    Tideland Prius Moderator of the North
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    The way I read that is that the benefit of plugging it in is to allow the battery heater to keep the battery "warm". (I use warm in quotes cause we're not talking warm in terms of human temperatures but warm as it near freezing as opposed to well below freezing).

    I guess think of a battery like a tank of water. If it's cold, there's less water to flow out (less amperage). Because the Volt and Prime have a true EV mode that relies solely on battery power, a warmer battery temperature allows for more power. A cold battery will be limited in output.

    That's more to do with how the vehicle operates rather than longevity.
     
    #10 Tideland Prius, Nov 22, 2017
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  11. john1701a

    john1701a Prius Guru

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    Yes. I witnessed it firsthand with my JuiceBox at home.

    Turned on the heater, saw it immediately draw from the plug.
     
    #11 john1701a, Nov 22, 2017
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  12. Tideland Prius

    Tideland Prius Moderator of the North
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    Thanks! So use remote A/C instead... cool.
     
    #12 Tideland Prius, Nov 22, 2017
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  13. CraigM

    CraigM Active Member

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    I think the 120v L-1 EVSE might not provide enough power to preheat without pulling some power from the battery. L-2 EVSE might not have to pull battery power, or it recharges quickly?

    Craig
     
    #13 CraigM, Nov 22, 2017
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  14. AnneLW

    AnneLW Member

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    What is considered "very cold" or "very hot" ?

    Where I live it hit zero F once in the past 20 years and usual January lows are about 20F.
    But last Summer we did reach 110F.
     
    #14 AnneLW, Nov 23, 2017
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  15. DavidA

    DavidA Prius owner since July 2009

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    14 F is the threshold for when the battery and EV mode will switch to HV mode, according to the manual; at least when starting or driving. I don't know yet how that relates to charging at that temp.
     
    #15 DavidA, Nov 23, 2017
  16. john1701a

    john1701a Prius Guru

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    I wouldn't expect it to. PHV charged just fine in colder temps, but at a slower rate.

    SM-G920V ?
     
    #16 john1701a, Nov 23, 2017
  17. Old Bear

    Old Bear Senior Member

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    I believe that's correct.

    One thing to realize is that when the Prime's climate system bringing the interior of the car up to temperature, it's doing the thermodynamic equivalent of accelerating up to speed. Once the cabin is warmed up, the Prime's heat-pump just has to cruise along, providing just enough heat to off-set the rate of heat loss through the exterior envelope of the car.

    That first burst of energy to bring the interior of the car up to 70F from 20F is much better done using power provided by the EVSE than drawing from the Prime battery's reserves once you start driving.
     
    #17 Old Bear, Dec 1, 2017
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