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Vestigial Tachometer

Discussion in 'Roadster: Technical' started by Kardax, Apr 30, 2008.

  1. Kardax

    Kardax Member

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    With the change to a single-speed transmission, the tachometer now serves no useful function. The 13,000 RPM redline is cool and everything, but it's basically impossible to hit it with one gear that goes to 120+ MPH.

    So... with the low top speed being a notable deficiency compared to other cars in the Roadster's price range, how long do you think it will be before Tesla makes another attempt at a multi-gear transmission?

    I realize higher top speeds don't matter to most customers for anything other than bragging rights (Germany autobahn users maybe), but it definitely has track implications. The Tesla Roadster will lose to cars half its price on a track with any sort of straightaway.

    -Ryan
     
  2. WarpedOne

    WarpedOne Supreme Premier

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    Actually, top speed is not the major downside. Drive train 1.5 increases max power to 225kW with same 50kWh of stored energy. That means you have enough juice for 13 minutes of driving at max power. Of course, doing that is impossible. I reckon about 100kW average power usage is quite attainable on track. Than means you have half an hour of driving and than you are off for at least four hours. Regenerative braking would not help you much because it is not aggressive enough for track racing. Most braking is done via classic brakes.

    Tachometer should be joined with speedometer with a single needle. Instead of existing tachometer there should be "powermeter", showing current engine power usage.

    Classic transmissions with fixed gear ratios and clutches are unsuitable for powerful electric motors as Tesla Motors has learned at great pains - kicking and screaming. If they ever try them again, they should try a different design. Maybe CVT, maybe hydraulics...
     
  3. tonybelding

    tonybelding Active Member

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    Sounds like a cool idea to me. :cool:
     
  4. Cobos

    Cobos S60 owner since 2013

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    In case they do implement a power meter they should also make sure it shows current flowing out and into the battery. As regenerative breaking throws power the other way. Might also be a good way to make sure people drive economically if they want to, like economode lights in gasoline cars.

    Cobos
     
  5. TEG

    TEG TMC Moderator

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    What I wrote last year:

    "On the Highlander Hybrid they don't bother with an RPM gauge because you have both eMotor and Gas Engine sometimes working alone and sometimes working together.
    Instead they have a tach like thing that shows total system power (in kW) being created.
    The Roadster has a tachometer, but perhaps that is just a carryover from the Elise cluster? With their complete control over RPM, Torque requested, and HP produced perhaps a new type of display should be shown which includes requested Torque, and HP produced rather than simply RPMs.

    I like the idea of mode selective displays. The regular display with minimal info, and the "geek mode" display with lots of details.
    Showing PEM voltage and current output, regen current, and all those little details that would be fun to track.
    I don't know how much info they already have on the VDS, but having access to as much as possible would be nice for those that want to see it."
     
  6. malcolm

    malcolm Active Member

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    The whole thing needs a re-design really.

    TEG's right. All of the current/voltage/power info is available now, it's just that it's stuck down by your left leg on the VDS, which desperately needs to be integrated into the main instrument binacle. Mechanical dials need to go digital and the whole thing needs to offer a variety of display modes.

    But not "fighter pilot HUD" - that's just silly.
     
  7. deenko

    deenko Member

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    The VDS does display that info, and more, but you are all right. it is a pain to look at while driving. The dash does contain a little lcd that always displays real time current consumption (inder the tacho). you can watch it hit high currents during acceleration, and 2 amps during idle. I do not know what it does during regen. The LCD also shows trip distance, distance till empty, current charge, etc.

    I actually prefer the minimalist approach. Just enough information without cluttering up the drivers view. I am guessing this minimalist approach is a carry over from british design mentality.
     
  8. malcolm

    malcolm Active Member

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    Oh yes.

    Ariel Motor Company
     
  9. vfx

    vfx Well-Known Member

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  10. SByer

    SByer '08 #383

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    Well, it's not great. But it's forgivable given how well the car drives. How many cars with automatics still have a tach? Pretty useless there, too.
     
  11. deenko

    deenko Member

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    I think the tach is useful for any ICE and/or anything that shifts gears. I found that you can get better economy/performanc out of an automatic if you monitor the tach to see the difference between speed and gear shifts. For example, when I drive long distances on an automatic, I set the cruise control just above a gear shift where the speed of the car and the rpm are within their optimal ranges.

    As for the roadster, I feel that the change to the single speed trany has made the tach useless. I do not expect TM to redesign the dash when the 2 speed was dropped so late in the game. otherwise, they would not be in production yet.
     
  12. WarpedOne

    WarpedOne Supreme Premier

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    >> I feel that the change to the single speed trany has made the tach useless.

    I'm still rooting for it to be replaced by a powergauge with some negative field for regen. Maybe an aftermarket mod? :biggrin:
     
  13. WarpedOne

    WarpedOne Supreme Premier

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    Power Gauge

    Something like this:
    attachment.php?attachmentid=65&d=1215863803.jpg
     

    Attached Files:

  14. TEG

    TEG TMC Moderator

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    #14 TEG, Jul 12, 2008
    Last edited: Apr 12, 2011
    I guess that it a photoshop mock-up done by moving numbers around?

    [​IMG]

    I suggested something like that a long time ago, after getting used to the kW gauge on my wife's highlander hybrid.

    Topic: WhiteStar dashboard

     
  15. WarpedOne

    WarpedOne Supreme Premier

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    Actually, it is a Paint / Paint.Net mock-up done by moving numbers around with a touch of added color. :)

    Has TM disclosed maximum regen power anywhere yet? I only remember that it is a tricky busines doing powerful regen (stability and such).

    Do you find that power gauge in Highlander helpful for reducing the consumption/energy usage? In my diesel car I have a "travel computer" that besides other things can show current fuel consumption. By paying attention at that number I was able to noticably lower my fuel expenses. It's consumption is rated at 5l/100km (47mpg) in extraurban driving and I manage to average 4.1L/100km (57mpg).
     
  16. TEG

    TEG TMC Moderator

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    #16 TEG, Jul 12, 2008
    Last edited: Jul 21, 2011
    To be honest, we don't spend a lot of time trying maximize efficiency when driving the Highlander.

    On the LCD Nav computer it has various charts showing power flow, MPG, etc.
    About the only thing I use is the display showing if it is running in EV mode or if the gas engine is running. At about 40mph if I hold the accelerator pedal just so it will stay in EV mode for a while. If I oscillate the pedal or push just a tad more it will cycle the gas engine even though it is going the same speed. Apparently if you let it spend more time using EV only then it helps efficiency.

    At freeway speeds it needs the gas engine almost constantly. The highlander is no Prius. It has a much larger, non-atkinson gasoline engine. Highway MPG isn't all that impressive ( ~25 ), but the city MPG ( ~30) is good for a vehicle that can carry 7.

    I sweat the details a lot more driving my RangerEV to work. The 9 year old NiMH pack has just enough capacity to get me there and back at about 62 MPH. If I drive too fast at any point then I have to draft behind a big rig or slow down more later to make up for it. My range is much longer if someone else helps push the wind, or if I slow down a bit. On the RangerEV there is an efficiency gauge showing +/-, and I do watch it a bit if I get to work and my charge gauge says I have less than 1/2 charge to make it back home later. I look forward when I can afford to replace it with another EV that has more range. Roadster and even 'S' are likely out of my price range now, so maybe I will end up with a 'Model 3', SmartEV, MilesEV, MiEV, or ?

    [ EDIT in 2011... '?' ended up being a Leaf (which I didn't know would exist when I wrote that.) Now I don't need to draft or fret the commute range anymore! ]
     
  17. vfx

    vfx Well-Known Member

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    I might try the KW gauge with the TDC as the zero point.
     
  18. malcolm

    malcolm Active Member

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    #18 malcolm, Jul 13, 2008
    Last edited: Jul 13, 2008
    Great design already, vfx.

    Can you put the negative numbers into green? Or maybe it should just be the curved scale markings - like the red section for 180 and 220?
     
  19. Alpine Driver

    Alpine Driver Member

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    As I was told, regenerativ breaking is a constant level. When you leave your foot from the right pedal, regen is active and delivers a constant energy flow back to the batteries. The amount was not numbered, but not to be that important big. Regen ist not combined with the brake curcuit; so the intensity of braking/speed reducing does not influence the energy flow back.
    Therefore, in my understanding, the different negative kW numbers in the modified gauge would be of no use. Or am I wrong?
     
  20. malcolm

    malcolm Active Member

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    With single speed they have one fixed profile; JB Straubel has said that homologation makes it difficult to allow owners to adjust this - but I think that the regen behaviour does vary with engine revs.

    So the regen profile is fixed, but not the regen amount.
     

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