TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC

The reality of tesla?

Discussion in 'Roadster 2008-2012' started by serious7, Jul 9, 2009.

Tags:
  1. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,105
    Location:
    Central New York
    The problem is that this is relatively new technology, so most likely that will not be true for quite a while. However, if you compare the Tesla to other vehicles like it with similar performance and include purchase price, it is cheaper in the long term scenario.
     
  2. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,105
    Location:
    Central New York
    Part of the problem is a lot of the battery weight is carried fairly high up in the car. A smaller, lighter pack carried lower in the vehicle will only help handling. Some suspension adjustments might be necessary, but that's not a big deal. You'll also gain more luggage space :smile: More likely you'll end up with a slightly lighter pack and a lot more range.
     
  3. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,105
    Location:
    Central New York
    As for true operating costs of the Roadster as compared to gas vehicles, this article is a good read EV WORLD: America's Irrational Petroleum Dependence

    We don't see the real cost of gas at the pump.
     
  4. Tdave

    Tdave Member

    Joined:
    May 16, 2008
    Messages:
    760
    Location:
    Owings Mills, MD
    You've already received a reply with a link and examples of range at different speeds for the Tesla.

    I want to point out that a gas powered car is also greatly affected by speed and aggressive driving style. My RX-7 sports car from the 90's would get 20 mpg in normal highway driving. When I drove it at the race track for fun I would get 5 mpg -- about 100 miles range from its large 21 gallon tank.
     
  5. serious7

    serious7 Member

    Joined:
    Jul 9, 2009
    Messages:
    9
    Electric cars have been around for as long as gas powered cars have been ?? It was just that the gas powered cars went ahead because they built more infrastructure and had more economic opportunities (they didnt even think about climate change back then). The technology is here, and has been for a long time.
     
  6. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,105
    Location:
    Central New York
    The ICE took over because oil was cheap and energy dense. Oil is no longer cheap, but it is still energy dense, and it's had about 100 years of constant development. BEV's have not. Up until about 10-15 years ago BEV's were basically working with 100 year old technology. The new lithium chemistries and sophisticated AC inverters are still in their infancy and are allowing EV's to really take hold. That along with the final realization that the petroleum ICE is not a long term solution. Lithium technology is developing quickly, this is new technology. Without it the Tesla Roadster would probably not exist.
     
  7. bolosky

    bolosky Member

    Joined:
    May 5, 2009
    Messages:
    685
    I think it's more likely that you'll wind up with just as heavy a pack and a lot more range. The reason for this is that you need a large quantity of batteries to generate enough power (as in rate of energy delivery) to make the car perform, so the size of the battery pack in the Roadster is determined by power rather than by range (energy).

    Of course, it may be that future technology will produce batteries that have both high energy and power density, in which case a lighter battery pack would make sense.

    Personally, I would be thrilled if when I replace my batteries in 2016 or so that I go up to a 500 mile range and stay at 2700 pounds. (Actually, I'll be really thrilled when my car just shows up later this year, but you all know what that's like.)
     
  8. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,105
    Location:
    Central New York
    Since Tesla has to run cells in series and parallel higher energy density cells could mean fewer cells over all for the same voltage and ah capacity.
    For example right now their cells are 3.7 volts at 2.4ah, there are already cells available at 3.7 volts and over 3ah. If at some point they hit 3.7 volts at 4.8ah per cell you can use half as many cells for the same performance and range, but actually better of both since you'll be hauling less weight.
    After a certain amount more range becomes pointless. It all depends on driving habits but I'd much rather have a lighter vehicle with 300 miles range than the same weight and 500 miles range. I'd never use that much range, and by hauling around less weight I'd need fewer batteries per mile.
     
  9. vfx

    vfx Well-Known Member

    Joined:
    Aug 18, 2006
    Messages:
    14,790
    Location:
    CA CA

    The battery box is part of the structural makeup of the Roadster.

    If Tesla decides to keep the box's weight the same to increase mileage using new batteries then likely mechanical changes will be minimal.

    But if the battery is filled with less of the new cells for similar miles per charge then will that less-packed box weaken the car's structure?
    In this case the car's handling setup will surely need modification because the car will no longer be balanced.
     
  10. ra-san

    ra-san Member

    Joined:
    Dec 26, 2008
    Messages:
    296
    Location:
    San Diego, CA
    That'd be a good problem to have :) I hope we're faced with that issue sooner rather than later.

    My own gut feel is that the current roadsters, particular the 08's, are likely to be left behind rather quickly, unfortunately, as the focus becomes solidly on the new platform for the Model S and subsequent family of cars. Even without the completely new platform we're already seeing the 2010's get substantial new abilities that may not ever be realistically possible to upgrade the 2008's, even as paid upgrades.

    I think Tesla will do more than most auto manufacturers in this area, and I guess I do hold up a hope still that they'll decide it's better to pull all the 08's into as close a conformance with the 09, er, 10's+ as possible to eliminate stocking and service overhead, but I'm afraid that'll just prove too costly to support. Don't know which way that'll go, how many spares of the original components they have, etc. but it'll be costly either way :)

    Battery box and associated PEM improvements are really going to depend on how many roadsters they manage to sell with compatible configurations (ie, 08->10 would take a lot of work to change to) before they change they whole approach with the model S "sled" platform.

    If they sell enough, it's conceivable there may be an aftermarket if not corporate upgrade capability. Hope so. As always though, it'll come down to what makes sense economically rather than what's theoretically possible, except for a few driven, genius type tinkerers (gotta love 'em - they help push the boundaries).

    I can see replacement packs for the roadsters weighing less, and even potentially having the weight lower, but expect they'd have to stay the same volume and strength/rigidity. Yeah balance would be different, and may take some tuning, but it'd be better. The pack would have to conform to the interface (voltage, power specs, interconnects) expected by the PEM or it becomes a bigger change. That's what we are seeing already with the 10's. It's a cascade of necessary changes, throughout the electrical/cooling system. Can't replace just one subcomponent without changing it all. I'm sure that extends all the way to the firmware and fleet of controllers/sensors too. Without stable module/interface boundaries, it'd be tough for anyone but Tesla to offer updated components.

    Anyway, I'm rambling now, as I'm want to do regardless, but especially when giving opinion rather than fact :)
     
  11. serious7

    serious7 Member

    Joined:
    Jul 9, 2009
    Messages:
    9
    which is exactly what i thought. I think more range for the same weight is what tesla might go for. Or else there'll be problems with structure.

    More range is never pointless. The more range=the better. Having a lighter vehicle will do nothing but probably make the 0-60 time faster and better handling of the car but that cant be possible because of the way the current roadsters is structurally designed. Its designed to carry the weight that its carrying right now. Any change in the weight as I and others believe will cause balance problems. Whether or not Tesla can fix that I don't know I'm no mechanic. But having more milage is always great. Especially for the fact that battery technology degrades with the amount of power it stores as the recharge cycles are used up. If you have a 500 mile range car, that will mean that you're battery replacement cycle will occur much later than earlier since you yourself have stated you only need 300 miles per charge. With a 500 mile battery pack, you wont have to replace your batteries for like 15 years( exagerated number)! So yeah, the more range, the better! I would always choose range > performance for an electrical car. That is just the more sensible thing to do.
     
  12. Mark06GT

    Mark06GT Member

    Joined:
    May 11, 2009
    Messages:
    19
    I would definitely choose longer range over a lighter car. Not because I think there would be problems if the car were lighter, but because it would do more to counter the arguments against the limited range of electric cars. Doubling the range of the roadster would all but silence those who say electric cars can’t compete in range with ICE vehicles. Driving 500 miles in a day is more than most people can stand. Any car that can travel longer than you can certainly has enough range capability.

    I don’t see why lowering the battery weight would be a problem. I think the roadster’s weight distribution is something like 35% front & 65% rear. Lightening the battery would bring the car more into balance. A lighter battery would require suspension changes (new shocks/springs and possibly changes in the control arm geometry), but other than that I think performance would improve since a more even distribution of weight would reduce the car’s chances of over steering. It would also make for quicker acceleration and braking. For somebody interested in tracking their Tesla or taking it to auto cross events, this could be quite attractive.
     
  13. vfx

    vfx Well-Known Member

    Joined:
    Aug 18, 2006
    Messages:
    14,790
    Location:
    CA CA
    This was my point. Changing the battery will be much more expensive than just the battery ($12K to 35K estimated) installation. That and the empty space in the battery box might need to be filled with something stronger/heavier than something like air or foam since the box itself is a structural member.

    btw I find the car has more under rather than oversteer.
     
  14. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,105
    Location:
    Central New York
    I seriously doubt the cells themselves are stressed members in anyway whatsoever. They may have built the battery box as a structural part, but there is no reason at all it has to be full of cells.
    I do think there is a practical limit for range and carrying around way more than you'll ever use is wasteful. I guarantee you that if Tesla could have used a lighter pack they would have and a lighter pack will not ruin the cars handling and it will help the acceleration and range, and it will actually most likely improve handling since a lighter vehicle with a lower center of gravity will handle better.
    As far as what is sensible, I'm not sure I see a $120K 2 seat sports car fitting that definition. 500 mile range is useless to me, as is 300 mile range, so I don't see any sense in carrying that much battery, even accounting for pack degradation. I realize some people may really need that kind of range, but most people don't, even if they may think they do. Bottom line, I don't see improving battery technology causing any real problems for current owners, however they are configured.
     
  15. Mark06GT

    Mark06GT Member

    Joined:
    May 11, 2009
    Messages:
    19
    Under steer is as much a product of the suspension setup as it is the front/back weight distribution of the car. Most car manufacturers bias their cars towards under steer because it is a much safer setup since over steering can result in a spin and total loss of control.

    If weight distribution is closer to 50/50, then suspension adjustments can be made to make the car more nimble. I'm not saying this would be cheap, but it would not be cost prohibitive either.


    JRP3...
    I should probably clarify my 500 mile range comment. I have no desire to drive 500 miles in one sitting, but as long as charging takes so much time and as long as high amperage charging stations are so few and far between, I would look at a 500 mile range as something that would let me drive 200+ miles to a destination and then back home again without having to worry about finding a high amperage outlet during the trip.
     
  16. Palpatine

    Palpatine Banned

    Joined:
    Sep 6, 2008
    Messages:
    1,354
    Location:
    Seattle
    You might be surprised what changes require new crash testing. I was told that Tesla had to do another crash test for the carbon fiber interior changes.
     
  17. bobw

    bobw Tesla Reader

    Joined:
    Sep 7, 2006
    Messages:
    318
    Location:
    Dallas, TX
    In some parts of the country a 500 mile range would come in handy. For example, it's 400+ miles from DFW to the Buffalo National River, in Arkansas. It's 225 miles to Austin. San Antonio and Houston are farther away.

    For that matter, it's 249 miles from Kansas City to St. Louis. Nobody thinks of Missouri as a big state, but it's big enough.

    It's a bit of a hike from the Bay area to Yosemite, too.

    I drove 625 miles from DFW to St. Louis and then back twice last year. I only did it one way this year, but it was a U-Haul truck. Now that was nasty.

    "It's a big country."
     
  18. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,105
    Location:
    Central New York
    That's on a new vehicle, we are talking about retrofitting an older Roadster with newer batteries. Luckily we don't have to crash test our old vehicles every time we modify them :wink:
     
  19. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,105
    Location:
    Central New York
    Absolutely, I don't disagree. But there comes a point where more range isn't necessarily a benefit, and it's probably a different point for every individual.
    A lighter weight pack of the same capacity will automatically give you more range and I doubt it will hurt the handling and structural integrity of the vehicle. The car has to have some flexibility built into it. Obviously it can handle a 200lb driver plus a 200lb passenger or a 150lb driver alone, a difference of 250lb right there. I'll bet it performs better with the lighter load.
     
  20. vfx

    vfx Well-Known Member

    Joined:
    Aug 18, 2006
    Messages:
    14,790
    Location:
    CA CA
    LA to SF is on every Tesla employee's mind. 400 to 500 -depending.
     

Share This Page

  • About Us

    Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.
  • Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


    SUPPORT TMC