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Battery drains very rapidly in really cold weather!

Discussion in 'Technical' started by Username, Mar 3, 2014.

  1. Username

    Username Member

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    I notice that when the temperature is way below zero Celsius, (32 F) I lose about 40% of my rated range.
    So a 400 km rated range capacity for instance, in real world conditions, gives me about 240 km.
    Anyone else have the same results?
    I'm setting the temperature to low and not "gunning" the accelerator either.
    The outside Temperature now is -14 C or about plus 12 F.
     
  2. nspollution

    nspollution Member

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    Yep, that's about the way it's supposed to work.

    For best results, pre-heat your car 1/2 hour before leaving. That will warm up the battery and increase your ability to regen while driving.
     
  3. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    If it's really cold, do two half hour sessions.
     
  4. cinergi

    cinergi Active Member

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    It'll appear you lose 40% but that's on short trips. If you take one long trip, it'll be closer to 20% (when it's super cold like -15C or colder). And as others have noted, pre-heating really helps especially with the initial hit for the first 15 miles.
     
  5. Chris Naps

    Chris Naps Member

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    You might consider this to be negative (which it is), but actually it is positive in a way. Cold weather is proven to improve battery longevity. The colder it is the happier the battery is. Just plug into a 120 V and keep the car outside and that should be enough to keep you from vampire losses. This would also be helpful for when you decide to leave, pre-heat the car and that will definitely improve efficiency.
     
  6. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Right. I can pre-heat the car (set at 23.5 with range mode off), then drive my 25 mile commute with range mode on and no heat. The car stays reasonably warm. I've only tested it down to -11 because as that's the coldest it's been here.
     
  7. yobigd20

    yobigd20 Well-Known Member

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    Ehhhh I consistently use about 160 miles range to go only 100 miles in cold weather. I basically lose about 35-40% range so that's pretty accurate. I'm a pretty inefficient driver though. You won't find me using any hypermiling techniques.
     
  8. cinergi

    cinergi Active Member

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    I don't hypermile at all either... Question is -- do you consume 160 miles of range to go 160 miles when it's warm? (we should compare apples to apples here -- in other words don't compare to rated, compare to what you'd otherwise normally get).
    Also curious -- those the Tesla Goodyear's (from your sig) or different tires?
    It gets that cold here and I don't see a 35-40% hit so something seems off here ...
     
  9. Todd Burch

    Todd Burch Electron Pilot

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    1. Don't forget under Settings > Vehicle you can turn range mode on. This decreases the power used by the car to heat the pack, instead letting it self-heat. It also reduces the maximum energy usage of the heater.

    2. As others mentioned, ideally preheat before you leave--the best thing to do is to preheat with range mode off, then turn it on when you leave.

    3. Use the seat heater in lieu of the cabin heater, or you can lower the cabin heat a little and rely more on the seat heater, which is much more efficient.

    I've never seen a 40% hit in cold weather. More like 20-25%. And that's for a shorter trip. Longer trips should see a lower percentage hit (more like 15%).
     
  10. Jeff Miller

    Jeff Miller Member

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    Last summer, my average wh/mile was 300. So far this winter (Dec 21 -> now), I'm using 473 wh/mile, or almost 60% more energy per mile.


    But,

    - I tend not to preheat.

    -Most of my driving is commuting to work, 13 miles 1 way. So on cold days, and most days this winter have been very cold in Chicago,
    the battery is heating the entire time, aside from the 1st mile. For some odd reason, the battery heater only kicks
    in after I drive a mile, not sure why that is.

    - On the few occasions when I have driven longer distances, the wh/m drops a lot - to maybe 370, I assume because eventually the
    battery heats up.

    -I try to mostly rely on the seat warmer, but frequently have to leave the defroster on low to avoid a foggy windshield.

    I haven't used range mode. Is it better or worse for battery longevity to allow the battery to heat itself up?
     
  11. neroden

    neroden Happy Model S Owner

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    I've seen my Wh/mi double in cold, snowy weather, on long trips. The snow in the wheel wells was the key problem, though.

    The car will also eat a huge amount of energy every time you start up from cold in cold weather. The resulting mileage is awful for short trips. I don't know why the battery heater isn't smart enough to run while plugged in, but it isn't.
     
  12. Chris Naps

    Chris Naps Member

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    I am not an expert in batteries nor can anyone with perfection answer this question, but I will put it this way, if you do not use the battery heater - the longevity of the battery as well as the percentage of charge will be greatly reduced, but also including the performance of the vehicle. The battery warmers are not meant to waste electricity, they are specifically manufactured and assembled for the reason of warming the battery up, in cold temperatures. The lower the temperature of the battery, the slower the reaction process happens which makes voltage drop. Lower voltage equals less miles. If you warm up the car before you leave, it will hold a higher voltage equaling higher range.

    You can read this to get the basics: http://chemistry.about.com/b/2008/01/04/cold-batteries-hold-charge-better.htm

    And this quote relates to the discussion and your question, "Expect hot batteries to run down more quickly; cold batteries to delivery a weaker charge. If you store batteries in the refrigerator, let them warm up before using them."

    I hope this helped!
     
  13. Jeff Miller

    Jeff Miller Member

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    Thanks. Your point about a cold battery being less able to deliver power than warm battery makes sense. It's less clear to me whether warming the battery should also be expected to increase the lifespan of the battery.
     
  14. Chris Naps

    Chris Naps Member

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    #14 Chris Naps, Mar 5, 2014
    Last edited: Mar 5, 2014
    You are welcome Mr. Miller! Let me make it 100% clear - I would definitely advise you to buy a cover from Tesla (http://shop.teslamotors.com/collections/model-s/products/model-s-outdoor-car-cover) and keep the car outside during the winter (cold temperature.) This will allow the battery to have a better longevity OVERALL. The link to the cover that I posted offers the ability to charge your car while it is covered outside (only if you don't want the car to get scratched and all of that, if you do not care don't buy the cover.) Just keep the car plugged into any socket whether it be a 120,240, or whichever appeals to you. This will have an adverse effect on the battery percentage from dropping in cold weather, but it will keep your battery at a constant level. This can increase longevity as well. As I read and also heard from a few people who had roadsters that they lost about 2.9% a year in totality of their pack. If they had 200 miles when they bought it, they would lose 2.9% of their total miles left each year. I heard that since the Model S has the battery warmer/cooling fans, it is much more software driven, and designed to last much logner - it will allow the Model S's battery to have a lower degradation of the battery in the long run. That is not to say that it won't happen, but to stay focused - the heater is suppose to happen - allow it to do its job. The heater does not add a lot of stress to the battery, it provides enough heat just to keep the batteries warm enough to allow for higher voltage. Extreme heat - for an example: 100 + degrees in direct sunlight for hours each day can damage the battery permanently that is why electric cars in hotter areas tend to degrade faster than in places with cold temperatures and winters.

    Another tip would be to leave the car outside during the night, and since you are able to set when the battery starts charging - program it to charge a hour or so before you leave, so when you go to jump in the car the pack will already be warm, and the car would have benefitted from the cold weather outside. That can also reduce degradation.

    I hope this clarified everything. If you want I can try to find the video of the roadster owner who said it was about 2.9% degradation a year - it was a video on YouTube.
     

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