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40 kWh and 60 kWh EPA range estimates, and how will it effect defferals?

Discussion in 'Model S: Battery & Charging' started by Rifleman, Aug 20, 2012.

  1. Rifleman

    Rifleman Now owns 2 Model S's!!!

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    Well, after much soul searching, I have decided that if the 40 kWh has an EPA range of 120 miles in normal mode, I am going to go with the 40, otherwise, I will go with the 60. If I go with the 60, I will probably need to either lease or defer to save up a larger down payment.

    The current dilemma is, with my reservation number, there is a chance that I will receive the email to configure before the first 40's are on the road, and I will have to configure before I know for sure if the 40 will do the job for me.

    My question for any representative from Tesla is (and I know that they read this forum), when will the EPA estimates on range for the 40 and 60 kWh Model S's be released, and once they are released, will people who have already locked in a configuration be able to make a change or defer without penalty?
     
  2. ddruz

    ddruz Member

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    Rifleman, this was my dilemma exactly. My number came up without enough hard information to make the kind of informed decision I prefer. I ordered the 60 kwh though at the end of the day the 40 kwh may meet all my range needs. I looked at the decision as buying insurance for an unknown risk, the unknown EPA range figures. This is not the way I like to do things.

    I considered deferral but realized that even when the EPA numbers are in, and even if they indicated the 40 kwh would just make it for me, I still would not know with much certainty the parameters for battery degradation over time. So the 60 kwh again buys me insurance for an unknown risk, the unknown battery degradation over time. Since deferring could not eliminate this unknown for me I felt it was most prudent in my case to buy the 60 kwh.

    I do hope, however, that Tesla will allow people to change their order when EPA numbers are known, as you suggest, for those folks for whom the battery degradation question is less of a question mark and the EPA ranges between the 40 kwh and 60 kwh are the biggest quandary.
     
  3. Doug_G

    Doug_G Lead Moderator

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    I would ignore the EPA numbers, personally. They won't reflect real-world usage.

    The performance numbers provided by Tesla are far more useful. Here's the range graph for the 85 kWh pack.

    graph1.jpg

    Tesla will no doubt provide similar information for the smaller packs, but for now just scale the numbers by the pack capacity - should be pretty darn close.
     
  4. jkirkebo

    jkirkebo Model S P85+ VIN 14420 EU

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    Well, 265/85*40=125 miles if the battery specs are correct. However, this could increase to maybe 130 miles because of lower weight since the 40kWh battery has fewer cells. I believe the chance for <120 EPA miles is quite low.

    But this is in range mode. Normal mode being 85% of range mode, I seriously doubt you'd see much more than 110 EPA miles. So if 120 EPA miles in normal mode is your fixed goal, go for the 60kWh which should go around 160 EPA miles in normal mode. Then you have a buffer for 25% degradation too and SuperCharger access.
     
  5. Rifleman

    Rifleman Now owns 2 Model S's!!!

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    The real question when doing the math yourself is do you use the 85/40 ratio, or the 300/160 ratio. Unless there is a significant difference in pack weight, I simply do not know how a 85 kWh pack is rated for 300 miles, yet a 40 kWh pack is rated at 160 (less than half the size, more than half the range)

    (265/85)*40= 124.7 Range Mode Range
    (265/300)*40= 140.8 Range Mode Range

    124.7*.85= 105.9 Standard Mode Range
    140.8*.85 = 119.68 Standard Mode Range

    I came up with the goal of 120 miles in standard mode because I drive 70 miles most days, and 90 once every other week or so (always known in advance, so range mode would be possible) I figure even with 20% battery degradation, I would be OK on range (and I could always drive a little slower, turn off HVAC, or charge in range mode to give a little extra buffer near the end of the batteries life).

    I really am hoping that the 40 kWh Model S can go more than 100 miles in normal mode without hypermiling, if it cannot, it really will mean that the cheapest Model S worth buying is the 60, and will further cement the idea that electric cars worth owning are too expensive for the average person.
     
  6. Doug_G

    Doug_G Lead Moderator

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    At a constant speed the effects of weight will likely be negligible. Weight comes into play when you're accelerating a lot. There is a minor effect on rolling resistance.
     
  7. NotTarts

    NotTarts Member

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    Do you have any sources for that? I'm just curious, because it seems very odd for the EPA to change the default settings, as that wouldn't reflect real-life usage for the average consumer.

    Not according to Tesla - they say the 40kWh model is 15% more efficient than the 85kWh model:

    300 mi/85 kWh - 3.5 mi/kWh
    160 mi/40 kWh - 4 mi/kWh

    Here's something I posted in another forum:
     
  8. EVNow

    EVNow Active Member

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    Don't forget the loss of range in winter.
     
  9. Zythryn

    Zythryn MS 70D, MX 90D

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    Are the smaller packs more efficient due to the lower power?
    The 0-60 times get slower as the packs get smaller. If Tesla ramps down the power available, will that increase the efficiency?
     
  10. NotTarts

    NotTarts Member

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    Definitely during acceleration, but even then I'm not sure if it's much of a difference because it would make, as it will still take a similar amount of energy to accelerate the car from 0-60 regardless of how quickly you do it (assuming the weight, transmission, motor, etc, remains the same).

    At highway speeds, I don't think it makes a difference at all. Even if there is more energy available, the electric motor will only use as much as it needs to maintain the speed, unlike an ICE where it would be using 8 cylinders when in reality it only needs half that.
     
  11. Johan

    Johan Took a TSLA bear test. Came back negative.

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    In an EV this could only affect EPA estimated range if the EPA test includes "flooring" of the accelerator, which I don't believe it does. Also, if power affected range negatively the Performance would be rated at less range than the regular 85kW, which it of course is not. Driven hard on a race track though you would get poorer milage (i.e. Higher watts/mile in the MSP compared to MS85, which again would be worse (but faster) than MS60 etc.
     
  12. Rifleman

    Rifleman Now owns 2 Model S's!!!

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    I am just getting to the point where I am hoping that we will get some solid info on the 40 and 60 kWh Model S's soon. I am starting to fear that the 40 is nothing more than a better looking Nissan Leaf, and not really a car that can be your primary vehicle if you live more than 25 miles from work. I made my reservation planning on buying a 40, and if I need to step up to a 60, I need as much notice as possible, so I can start figuring out how I am going to come up with the $10k difference. If they are unable or unwilling to give hard numbers on the 40 at this time, at least giving reservation holders an assurance that they will be able to change their order or defer to a latter date would go a long way to easing our fears. My number is high enough that this may or may not be an issue, but I am sure that there are people receiving the email to configure already who are in the same situation that I am.
     
  13. Doug_G

    Doug_G Lead Moderator

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    I think the 40 could only be better than 40/85 times the above range graph. If that's good enough for you then you should be fine.

    Personally I would strongly recommend the 60. That gives you Roadster-type range, and that is ample for in-town use.
     
  14. NotTarts

    NotTarts Member

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    Rifleman, I highly doubt the range is going to be under 100 miles. Like I said before, 140 miles is what I expect the EPA estimate to be, which gives plenty of leeway for varying conditions.
     
  15. onlinespending

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    The 40 kWh option was always there simply so Tesla can claim that the Model S starts at sub $50k (after tax rebate). It's no different than any other car manufacturers "starting at" price. Obviously the average equipped Model S will be significantly more.

    When I first looked at the Model S I was dead set on the 40 kWh option since I recognize that well over 90% of my (and most people's) driving is well within a 100 mile radius (for commuting, running errands, going out to eat, to the gym, etc.). For the few times I'd need to make a road trip I'd either rent a car (or use my current ICE, if I decide to keep it). Quite frankly, I'd rather put the miles on a rental or beater for longer trips anyways! But if I don't end up getting the MSP (because I would love that Performance), then I am a bit torn whether to get the 40 kWh or 60 kWh. The 85 kWh option is pointless to me, since that extra range will essentially be used once in a blue moon, and the 0.3 second 0-60 benefit from 60 kWh to 85 kWh is pretty much negligible. On the other hand, going from 40 kWh to 60 kWh gives you extra range you're more likely to use (or benefit from as degradation sets in), you get a full 0.6 seconds improved 0-60 time, and have the added ability to SuperCharge.
     
  16. MikeK

    MikeK R#129, TSLA shareholder

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    My friend barely gets 70 miles of range from his LEAF, which is worse than I get in my 10 year old RAV4-EV. I expect the 40kWh car to exceed the range of my RAV, which satisfies my daily driving needs to the extent that my poor Prius has to be jump started whenever I drive it.

    I'm getting the 60kWh so that I have the range for somewhat longer trips, like Monterey or Sacramento (with a little opportunity charging perhaps), and so that I have the ability to Supercharge.
     
  17. stopcrazypp

    stopcrazypp Well-Known Member

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    No way the 40kWh will be another Nissan Leaf. The new RAV4 EV, which has almost the same battery (slightly larger at 41.8 kWh) gets 100 miles of range easily in the real world. In range mode, the RAV4 EV would get 113 miles, and it has a crappy 76mpge rating (more forgivable given it's an SUV) vs the 89mpge rating the 85kWh Model S gets.
    http://www.greencarcongress.com/2012/08/rav4ev-20120803.html

    The 40kWh Model S will likely be slightly more efficient than the 85kWh (because of lower weight), but I don't expect as much as Tesla predicts (300mi/85kWh=3.53mi/kWh, 160/40kWh=4mi/kwh, corresponding to 101mpge for the 40kWh Model S, ~15% better). If you use Tesla's (likely optimistic) prediction, then scale 265mi*160mi/300mi = 141 miles EPA. If you want to be conservative (assume 40kWh is not more efficient than 85kWh), just scale the 265mi*40kWh/85kWh = 125mi EPA range.
     
  18. EVNow

    EVNow Active Member

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    Yes, I think the 40 kwh will mostly get above 100 miles. Freeway driving in the winter could be the exception.
     
  19. Rifleman

    Rifleman Now owns 2 Model S's!!!

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    I also think that the 40 will get a legitimate 100 miles for daily use, but my real hope is that it will get a legitimate 120 miles, at least when it is new, so that I will will not be sweating the occasional 90 mile day in a few years when the battery has started to degrade. I have little doubt that the 40 will do the job for me on day 1, the real question is will is do the job for me on year 4. If its normal mode range is 120 miles on day 1, I think that it probably will. If I go with a 40, my plan is to save that 10k, and in 6-8 years or so, when degradation is starting to be an issue, and the car itself is paid off, buy a new battery.
     
  20. dsm363

    dsm363 Roadster + Sig Model S

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    You'll definitely want to pick the pack that gives you easily over your 90 mile drive in standard mode with plenty of buffer for unexpected trips, bad weather, battery degradation. 60kWh might be way to go anyway since Supercharging will be included if that is an option for you. Picking the 40kWh and upgrading the battery might not give you Supercharging capability in the future.
     

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