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After a night in the Cold

Discussion in 'Supercharging & Charging Infrastructure' started by Pruitt, Jan 3, 2020.

  1. Pruitt

    Pruitt Pontificating the obvious

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  2. Akikiki

    Akikiki A'-Lo-HA ! y'all

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    Sound perfectly normal from wheat we have heard others in cold regions report when supercharging.
     
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  3. swaltner

    swaltner Active Member

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    Your screenshot isn't visible. Gives a permission denied message....

    As mentioned, that's normal when the battery is really cold. Common wisdom is to charge the battery before going to bed on a multi-day trip instead of waiting for the morning. Don't let the battery cool down overnight if you expect to get Supercharging speeds first thing in the morning. If you charge the night before and then drive a couple hours on the highway to your first charging stop, you should get the battery warmed up enough to accept a full charge rate.

    "What's his name" posted a video at one point showing not being able to get a decent charge rate at a Supercharger and got the battery to warm up by doing several full power accelerations. Alternate between full throttle and full regen (which isn't much with a cold battery) or even use the brake pedal a little. Do that on a several mile drive to get the battery warmed up enough to accept some charging (which will tend to warm up the battery as well). 5 minutes of really hard driving should have avoided the 20 minute delay at the start of the charge cycle.
     
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  4. Pruitt

    Pruitt Pontificating the obvious

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    Don't know why you're getting a "permission denied" message.

    Not complaining about the slow start to supercharging. Just thought it was interesting.

    It's pretty hard to keep the battery from cooling down when it's parked outside at a hotel on a cold night. I intentionally waited to charge until morning so the battery wouldn't eat itself for the first fifty miles of travel the next day. By the time the car was charged in the morning, the battery was fully warmed up.
     
  5. mswlogo

    mswlogo Well-Known Member

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    The battery doesn't "eat itself" for first the first 50 miles when cold. You might not get much regen, but on the highway it's not that big a deal. And you will have to warm the cabin. But it takes was more energy to reheat that battery back up for supercharging than the little bit of loss due to low region and a cold cabin. Heating the cabin at the supercharger the next morning isn't free either, you are paying for it. You might also have a snow flake which will initially limit range, but as the battery warms up that lost range should return.

    You'd be better off charging while the battery was still warm the night before.

    If you use the Navigation to Superchargers on the car it will start start pre-warming the battery while driving too the supercharger. This isn't for "free" but your charge session can go faster. If it's very close it won't buy you much. And if it's too far it won't start pre-warming until "close enough".

    So your 50 miles might be 10% less efficient because the battery is cold. But 20 minutes of juice on the supercharger is probably 100% of 50 miles (or more) of energy.
     
  6. Pruitt

    Pruitt Pontificating the obvious

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    Well, when the battery is very cold my watts per mile run well over 400, even with all climate controls (seats, wheel, cabin air, etc.) off. Once the battery warms up to the point that the dashed yellow line (and caution triangle) disappears completely, the rate drops back to very close to the summer rate of just over 300 w/m. That takes 50 miles or more on a road trip when the temp is below 20 degrees, as I learned in an early December trip west from NJ to WY. When I supercharged in the morning, the energy per mile starts out nearer 300. So it looks to me like the battery is eating itself. Can you explain in more detail how I'm not correct?

    My car is a 2016, so actually heating the cabin at a supercharger is free for me (free supercharging for life).
     
  7. mswlogo

    mswlogo Well-Known Member

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    #7 mswlogo, Jan 11, 2020
    Last edited: Jan 11, 2020
    So your 25% less efficient over 50 miles, that’s 12 miles. Compare that to 20 minutes of Supercharging, how many miles is that? It’s a whole lot more than 12 miles. Also what is your time worth?

    You have to look at your time and total energy for what’s best. Not what the wh/mi says. Also fast heating of the battery on the SC is probably harder on the battery than gradual warm up while driving.

    This is just my opinion. You can do what you want but I always try to take advantage of charging an already warm battery when I can. Less time, less energy and less stress on the battery.
     
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  8. M3BlueGeorgia

    M3BlueGeorgia Active Member

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    Again, that's why you should always charge before sleeping while the battery is still warm from the drive..

    I typically add 5% to the trip estimate to account for power used in warming up the cabin in the morning and some extra overnight margin, but its typically closer to 2 kWh.
     
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  9. Pruitt

    Pruitt Pontificating the obvious

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    Well, it's not 12 miles. 400 is 33% more than 300, not 25%. So 50 miles would use up more like an extra 16.6 miles, not 12. Plus I said "well over 400", not "right at 400", While the actual number varies based on all a wide variety of factors (which is why I didn't list a specific number), it generally ran 450 or a bit more, meaning that 50 miles of battery heating used over 75 miles of warm weather travel distance.

    Finally, heating the battery at a charging station probably stresses the battery LESS than forcing energy out of the battery to propel the car in a sub-zero chemical reaction, when the battery is also trying to warm itself at the same time. Just as the supercharger provides only the amount of charge the battery can safely take based on it's condition, it appears to also heat the battery only at a rate the cells can safely tolerate.
     
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  10. mswlogo

    mswlogo Well-Known Member

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    #10 mswlogo, Jan 11, 2020
    Last edited: Jan 11, 2020
    If your push 450 wh/mi that’s not all due to cold battery. And I disagree pulling a couple kw from the battery to cruise around is way less stressful than a nice summer for super charging.

    we can agree to disagree.
     

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