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Cold battery means not so super supercharge

Discussion in 'Model S: Battery & Charging' started by Jess, Mar 17, 2014.

  1. Jess

    Jess Member

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    I was on a business trip & took my Tesla. My plan was to charge in Bloomington, IL in order to get home. When I plugged in, the numbers said 5/6 miles/ hr in the charging rate. Long story short, because it was 30 degrees outside, the battery takes 1min/degree to warm up & the car must warm up before receiving supercharge. Needless to say, I hadn't planned to need to charge a full hour to get only 40-50 miles of charge. This was a HUGE inconvenience and Tesla needs to improve this. How many of us own cars in climates other than CA where a NORMAL winter is 30 degrees? If it's going to take 2 hours to get 100 miles of charge at supercharger, tesla needs to put that info out there instead of claiming charging at superchargers is incredibly fast. Only if you are in Spring weather. It's the first negative thing I've ever had to say about my Tesla, but I will not be taking it on road trips where I don't have a 2 hr window to charge at each station. Sadly, I will use my ICE car.
     
  2. scaesare

    scaesare Active Member

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    Well, that unanticipated time must have been a bummer.

    I hadn't really thought about it before because I'm typically hitting a supercharger after some period of road-trip driving and the car is already warmed up. It makes sense, however... Li-Ion batteries cant accept significant charge surrent when cold.. hence power limiting regen well below it's 60kW maximum... much less the 120kW from a spuercharger.

    Was this a situation where the car had been parked nearby and the battery cold-soaked when you arrived at the charger?
     
  3. ckessel

    ckessel Active Member

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    I can understand this was an unexpected inconvenience. You noted that it takes time to warm up the battery, so that first 50 miles did take forever. Once the battery is warm, that second 50 miles isn't going to take another hour. And you knew this as you typed your post given you now know the 1min/degree warmup. You purposefully exaggerated the time it'd take to get 100 miles.

    Tesla should absolutely make clear the way superchargers work. I knew a cold battery took some warm up time, but not how much or for how cold or the impact on charge levels. I still don't know the impact and you've got a really good point that Tesla needs to provide more data so people can plan. But that message is going to get written off if it's wrapped in hyperbole.

    I've super-charged in mid-30's weather and not had an issue, but my car was warm from the drive to the supercharger. I'd expect that's the typical driving scenario, not pulling up to one dead cold.
     
  4. doug

    doug Administrator / Head Moderator

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    So the issue was the cold battery and not the supercharger, as suggested by the title. Minor change made to tread title.
     
  5. TexasEV

    TexasEV Active Member

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    If you have to hit the supercharger at the beginning of your trip rather than after driving a while, it sounds like you needed destination charging. Plugging in at 120V at your destination wouldn't have added significant range but it would have kept your battery warm and ready for supercharging.

    I don't think what you are describing is the typical use of superchargers. They're intended to replenish a charge after driving 100 or more miles, not a car that had just been parked in the cold.
     
  6. Jess

    Jess Member

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    Yes, the car had been "cold" when I drove to the supercharger. It took me an hour to get 50 miles and because I was nearing 200 miles of charge, the charge rate was slowing, so I believe it would take 1.5-2 hrs to completely fill my battery. If I had arrived there with 20 miles total in my battery, yes, getting to 100 miles would have taken less time. My post was not exaggerated. When I spoke to the Tesla rep, he said as the battery gets fuller, the charging speed slows down. So my point is if you go to a supercharger expecting to get a full battery quickly in cold weather, you are in for a disappointing surprise and should allow 1-2 hrs to get a full battery worth of charge. If you arrive with almost no battery left, and your car is warm, you will get supercharger effect.
     
  7. ckessel

    ckessel Active Member

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    That's always been true, cold or not. Charging the last 20% is slow and that last 5% takes forever. Tesla notes that in their curve on the Supercharger section of the website, showing 75 minutes for a full charge, which is obviously in ideal conditions. A harsh early lesson if you didn't know batteries slow down charging dramatically as they get full.
     
  8. EdA

    EdA Model S P-2540

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    This is a learning experience. I did the same thing, pulled into the DE supercharger at night and charged for half hour.
    Stayed nearby, woke up the next morning, it was 22F tried to supercharge... Fortunately I was able to drive down
    to Bethesda, MD and charge there on my way to my destination.

    Always supercharge with a heated battery...
     
  9. ckessel

    ckessel Active Member

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    Yea, if you can even get a 120v charge overnight, it's a big help in cases like this.

    Tesla's expansion has been awesome, but there is still a long way to go nationally to support EVs in general. It's often hard to find even a 120v plug, even in parts of the country that are quite EV friendly. I live in Oregon and takes trips to Ashland, which is as hippy/liberal/eco/green as you'll ever see, but most of the hotels there don't have an outside plug of any kind yet.

    Edit: there are usually outside plugs, but often not in a position to be accessible from the parking lot.
     
  10. AnOutsider

    AnOutsider S532 # XS27

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    I feel like this is something Tesla should share with owners. I called them and reported issues with the JFK supercharger back in January. Seeing this post, I'm wondering if the issue was because I stopped at a friend's house in Queens for an hour, then drove the 15-20 minutes to JFK and my battery was still cold?

    I never received a follow up on the issue (whether it was my car or the SC since I hadn't SC'd in a while), and I've certainly never known that when the car is cold the charge rate would be slower.
     
  11. Al Sherman

    Al Sherman It's about THIS car.

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    Yeah. Me either. I guess I should have known, and it makes sense but I never considered it. Glad the OP brought it up for this reason. The few (3) times I've supercharged I drove a long distance to the Supercharger. Good to know for planning purposes if applicable.
     
  12. ckessel

    ckessel Active Member

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    I knew in the abstract just because regen is so limited when it's cold, thus dumping energy into the battery must be restricted. But, yea, it'd be good to have some details out of Tesla on it.
     
  13. huntjo

    huntjo Member

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    Yeah most of the time the car has been driven at least 100 miles or so before needing to charge so it is warm already. Why was yours cold?
     
  14. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    #14 FlasherZ, Mar 17, 2014
    Last edited: Mar 17, 2014
    Unfortunately, this is the way things are:

    Cold battery: It's true that a Lithium-Ion battery can't take a high rate of charge when it is cold. This isn't an issue if you've been driving and you're stopping to charge along the way, as your battery is warm. You can see below that my wife pulled into the Supercharger, plugged in, and immediately began charging at > 108 kW or so. If you're using a local Supercharger as a launch point, it's best to pre-heat the cabin to warm things up before you head to the Supercharger in the morning, or find a 120V outlet to keep things warm throughout the night.

    Full battery: The charge current must be reduced as the battery gets full. At the Supercharger, if you insist on filling up completely, you'll spend roughly an hour and 20 minutes or so. Here's a curve from the Normal, IL Supercharger from last Thursday night. Note that the car hit 250 miles at 19:36, and my wife finally disconnected from the SpC at 19:54 with 266 miles (99% SOC). The green->red transition is where SOC > 90%, so you can see that > 30% of the time was spent in the last 10% of the charge - 16 miles in 18 minutes at the very top of the battery. Superchargers are set up so that the fast charging to ~200 miles or so should get you to the next hop, where Supercharging has its greatest benefits.

    supercharge.png

    Etiquette note: no other Teslas were harmed in leaving the car on the charger over an hour, phone numbers were left and no other cars pulled in during that time, my wife was a block away and could have moved if required.

    - - - Updated - - -

    (I'd suggest this be moved back to the charging & infrastructure stds forum... this is a good topic in general, not just a regional issue.)
     
  15. Electric700

    Electric700 Member

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    #15 Electric700, Mar 17, 2014
    Last edited: Mar 17, 2014
    Isn't this an opportunity for Tesla to introduce a new message on the car's display? It could stating something like "Charging at a reduced rate due to low battery temperature. To avoid this, please preheat the car when the outside temperature is below 40 degrees Fahrenheit."
     
  16. yobigd20

    yobigd20 Well-Known Member

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    you can't supercharge a cold soaked battery as it will destroy it. tesla has a few patents around this and heating up the battery pack to an optimal level before fulling cranking on the supercharge at max speed. this is completely expected behavior and by design. I wouldn't want it to work any other way (unless I wanted to destroy my battery for some odd reason).
     
  17. RDoc

    RDoc S85D

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    An hour to heat the battery seems a bit excessive though. Is that really the fastest the car can do, or is the software just not set up to first warm up the battery if it's plugged in?
     
  18. dsm363

    dsm363 Roadster + Sig Model S

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    Jess: didn't you have to drive at least a few miles to get to the Supercharger? Trying to figure out how you arrived with a cold pack.
     
  19. islandbayy

    islandbayy Active Member

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    When I was stuck in Cleveland on the freeway at 11pm, and no one would tow me, my car got cold soaked down to 11degrees with a dead battery. The next morning, found a tow to the supercharger 3 miles away. It took close to 30 minutes before it would start charging at all. That whole while it was just heating the pack. Then it started at 1kW, and slowly climbed, about 1kw increase every 2 minutes until about 25 kW, then it was increasing by 1kW about every 15-20 seconds, once it hit 50kW, then it went up rather quick, but then the taper kicked in and started dropping again.
     
  20. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Interesting question (to me at least): was this with climate control on, or off? I thought the diagnostic screen showed the heat pump for battery pack heating and cabin heating to be linked, and am wondering whether there is any benefit to running climate control while the pack is heating up?
     

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