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 or making a Paypal contribution here: paypal.me/SupportTMC

Non-traditional ideas on improving range

Discussion in 'Model X' started by Herbys, May 1, 2013.

  1. Herbys

    Herbys Member

    Joined:
    Jul 3, 2012
    Messages:
    66
    We have been discussing new battery tech and other such things for a while, but I wanted to start a thread on how range could be improved in other ways not related to battery capacity. Some ideas I can think of:
    * Tracking distance sensors. Given that tailgating on a vehicle can get HUGE benefits for range (around 30% based on my occasional quick tests getting close to some large vehicle with my S) but also HUGE decreases in safety (that's why I only did these tests in the name of science :) I presume that adding distance sensors integrated with cruise control could mean very relevant highway savings. Obviously you don't want to tailgate someone to save electrons, but if you put an effective tracking system you can get within safe distance and still get some significant aero savings. Maybe this could get a 10% range increase (when used).
    * Better regen. Discussed in other threads, but regen is not terribly efficient. This is in part due to inherent losses in the process, but it could be improving in different ways, including having two motors (enabling a bigger range of regen), a small but highly efficient transient battery (reducing loses in the charge/discharge cycle and allowing for bigger regen currents), improvements in electronics and integration of regen with the brake pedal. I've made some math on this in other threads, and if all those problems could be solved (especially finding a small "cache" battery that doesn't add much weight but can hold the full kinetic energy from a slowdown from 60mph and that has minimal losses) one could see a 10-20% increase in city range.
    * Better driver guidance. This is tricky, but the color indicators in the tesla dashboard tell you how much energy you are using (or getting) and not how efficiently you are driving. For example, if you are going up a hill, it tells you are using lots of energy, but most of that energy goes into a form that's not "spent", just transferred to potential energy, so when you go down you will recover all of that. Same thing when accelerating, minus the increased loses at higher speed. So if we could have in the dashboard a good way to represent how much REAL energy you are actually "wasting"(that is, using in a non-recoverable way) per unit of distance, deducing that which will be recovered later (i.e. 100% of potential energy, 60% of kinetic energy, 0% of friction losses) you would have much better guidance on how to drive the car. In fact, maybe the whole NYT fiasco would have been avoided, since the driver would have KNOWN that accelerating and braking continuously is NOT the way to "make better use of the regen" as he stated. A driver getting more actionable info on how efficient the car is being at each instant could make a significant impact on driving habits, and on range as a result. Difficult to quantify though, but since the difference between a spirited drive and a very conscious drive seems to be significant, I would bet this can be in the high-single digits for both city and highway driving.
    * Non-traditional aero improvements. These include rear-view cameras (as already shown), potentially active spoilers in front of the tires, dynamic aerodynamics (e.g. a change in the front bumper shape or distance with speed, maybe some sort of diffuser on the back, a sliding wheel cover at speed - hope not, would be ugly -, tighter-fitting weatherstrips alongside each vertical panel union, etc.). These could add some highway efficiency.
    * Road-quality sensors allowing for an even lower ride.
    * More aerodynamic wheels? With most of the braking coming from regen (at least on a 4WD vehicle), brakes should be able to do with less ventilation.
    * Better GPS mapping. Yes, you could get some better "range" if the mapping app was optimized (optionally) for energy consumption instead of for time. Maybe the map could show both options, and clicking on the energy efficient route (which would optimize for distance and uniformity, instead of time) would switch to that route. Or maybe it could do it automatically when you select a route that is more than, say, 30% of your current charge.
    * Better thermal management. Can't offer suggestions to this, but I would think there's lots to do in this area (such as moving load to the batteries on the center of the pack as one arrives its destination when driving on cold weather, so the heat is concentrated on cells where it would actually last) which could somewhat improve range in cold weather.
    * LED headlights. Not much to gain here, but everything adds up.

    That's what I can think of for now. Any other crazy ideas?
     
  2. GSP

    GSP Member

    Joined:
    Dec 28, 2007
    Messages:
    1,993
    1) I would add low rolling restance tires, of narrower width for lower frontal area.

    2) I like the active front spoiler idea. The Model S could also use a passive spoiler like the Volt has.

    3) The 12 V system could be optimized to use less power and energy, both when the car is on and when it is off. I really hope Tesla attacks this and makes big improvements. This is one of the few areas they are behind the incumbent automakers.

    4) the best improvements for regen would be AWD to allow regen braking with the front wheels, and paddle "shifters" to allow driver control of regen braking level like the ELR will have.

    5) heated steering wheel (20 W) and rear seats (80 W), so you don't have to use the 6000 W cabin heater as much.

    GSP
     
  3. agentsmith1612

    Joined:
    Feb 9, 2013
    Messages:
    98
    Location:
    Germany
    Very good idea, with my ICE car I tried it sometimes to drive a long way behind a truck, (i know not so save) but I saved somthing around 10 % of fuel, while driving at 90 km/h (56 mph)

    Totaly agree, but how to calculate this numbers ? There are a lot of parameter variable, the bigges parameter will be, "how fast the driver want to accelerate", for efficienty slow acceleration is better, but who wants to do that in a Tesla ?

    In the Model X Tesla wanted to do that with the cameras instead of mirror, but there were some law restriction that avoid that.
    But the general aerodynamic improvements are a good idea, I like our idea with the automatic covering of the rear wheels and the even lowering of the car, the automatic spoilers and diffusers, too. But think about the velocity, only at speed above 50 mph you can see an effect on the drag force, below 50 mph aerodynamics can be ignored to an cartain level.

    I have another idea to improve the heating of the cabine. Use the heatpump princible instead of resistance heating. It can save up to 70 % of electric energy for heating. In the car is already the heatpump principle but only for one way. (The clima compressor for the AC).
     
  4. Al Sherman

    Al Sherman It's about THIS car.

    Joined:
    Nov 29, 2012
    Messages:
    1,692
    Location:
    Batesville, IN
    I always thought a cruise control that would "attempt" to be at or under a certain wH/mi setting. Maybe have a mph floor setting to keep it safe on highways. Don't know how they'd do it but I assume it could be done.
     
  5. Raffy.Roma

    Raffy.Roma Active Member

    Joined:
    Jul 22, 2012
    Messages:
    3,209
    Location:
    Rome (Italy)
    This a very good idea. You could use the paddle on the steer as a brake and you would use only rarely the true brake. A lot of energy savings.
     
  6. TXjak

    TXjak Owner/Investor/Advocate

    Joined:
    Jun 1, 2011
    Messages:
    326
    Location:
    Austin, TX
    #6 TXjak, May 1, 2013
    Last edited: May 1, 2013
    Check this EV mapper out. I'm going to test it one of these days on a road trip in Texas. Interestingly, when I entered a round-trip from Austin to Fredericksburg, it used a different route for each direction.
     
  7. neroden

    neroden Happy Model S Owner

    Joined:
    Apr 25, 2011
    Messages:
    3,529
    Location:
    Ithaca, NY, USA
    It isn't?

    I've been seeing really very good regen numbers in my model S, or at least I think so. The peaks are off the chart (on the bottom). Well, I should mention my driving situation: it's down steep hills and up again. The regen works really quite well going down a steep hill.

    I'm not sure exactly what makes the difference here, but the regen is *far* stronger in terms of regenerated energy going downhill than it is on the flat.

    The regen in the Model S feels very powerful when it's being used to decelerate when going downhill -- I decelerate nearly as quickly as I would on the flat, but there's *much* more energy regenerated. I do have to hit the brakes once I'm at ~10 mph, but until then the battery just seems to suck up whatever energy I give it by rolling downhill. As far as I'm concerned, the purpose of regen is to eliminate the "cost" of going up and down hills -- the up and the down really do seem to cancel each other out, leaving me only using the going-horizontal energy.

    I wonder if there is some significant difference between the effectiveness of regen on hills and on the flat. Perhaps regen is limited by traction on the flat, but the same traction limit allows for more regen on a hill? That would make sense.
     
  8. Herbys

    Herbys Member

    Joined:
    Jul 3, 2012
    Messages:
    66
    I'm almost certain the model S uses a heat pump already, there's no resistance. You can hear it working when the car is parked.

    - - - Updated - - -

    @neroden: Do this experiment: take a long, uniform downhill road at a constant speed (say, 25mph) and take note of how much power you are getting from regen. Then take the same road uphill at the same speed and note how much power you are putting in. You'll see typically a 2:1 difference. That difference is the sum of loses in the drivetrain, inefficiencies in the acceleration cycle and inefficiencies in the deceleration cycle. From claims by tesla the acceleration cycle is extremely efficient (over 90%) so the deceleration cycle has to be significantly less efficient. A friend that works in electric motor design (not for cars though, but he knows his stuff) told me that typical EVs get less than 50% regen efficiency. He suspects the Tesla is better, but doubts it gets much more than 60%. So apparently there's room for improvement there, in addition to the possibility of doing MORE regen so less braking is needed.
     
  9. arg

    arg Member

    Joined:
    Aug 22, 2012
    Messages:
    740
    Location:
    Cambridge, UK
    I haven't been able to find absolute confirmation, but various reports strongly suggest that Model S has both heat pump and resistive heater - resistive for use in extreme low temps where the heat pump efficiency is low and the output insufficient.
     
  10. NigelM

    NigelM Recovering Member

    Joined:
    Apr 3, 2011
    Messages:
    13,257
    Location:
    Sarasota, FL
    Gravity.
     
  11. Johan

    Johan Took a TSLA bear test. Came back negative.

    Joined:
    Feb 9, 2012
    Messages:
    6,890
    Location:
    Drammen, Norway
    A bit blunt? :smile: In the first sentence he says "regen is far stronger..." going downhill. Obviously this is due to gravity. In the second sentence he says he has the impression that not only is is stronger, but also more effective going downhill. I would think the reason for this observation, if it holds true, is that with low regeneration you have your mechanical and heat lossses and a little bit of energy left for actual recharging of the battery, whilst with high regeneration (going down a hill at higher speed) you have the same mechanical and heat losses but perhaps these losses increase to a lesser extent as the total regenerative braking increases, hence giving a better efficiency?
     
  12. NigelM

    NigelM Recovering Member

    Joined:
    Apr 3, 2011
    Messages:
    13,257
    Location:
    Sarasota, FL
    Huh? Gravity pulls the car downhill, it's not losing forward momentum as it would on the flat.
     
  13. EchoDelta

    EchoDelta Member

    Joined:
    Mar 5, 2012
    Messages:
    732
    Location:
    Seattle, Planet Earth
    +1
    I like cruise control to gain economies in long trips but sometimes it gets power-hungry for a slight uphill in which I would have gladly slowed down a few mi/h; and my mind churns 'how do I know if the optimization of turning off cruise in this segment is better than my non-optimized manual driving'

    I guess it would be a 'smart cruise' - e.g. you turn your power-cruise-control on and it keeps at or below the current wH/mi value (plus 10% for a bit of variation) and within +3%,-10% of current speed (for example). The speed below which it would beep and turn itself off and become 'normal cruise' could be clearly indicated in the dash. I'm sure Tesla can design something sound and safe.
     
  14. Herbys

    Herbys Member

    Joined:
    Jul 3, 2012
    Messages:
    66
    But one of the interesting aspects of an EV is that efficiency is not necessarily worse when accelerating stronger than when accelerating slowly. In other words, the car is not less efficient going from 30 to 50 in one second than it is when doing the same in five seconds. So keeping a certain energy output via cruise control wouldn't gain you much, it would just make you stay at the desired power for a longer time by accelerating more slowly to the desired speed. If you can afford a few seconds of trip time to save energy, the more efficient way to do it is to accelerate as hard as you can (within some limits) and then keep your top speed a bit lower than you would have by accelerating faster. Unlike almost every other car, the Model S is not less efficient if you have a heavy foot, efficiency is mostly derived from the average speed in your trip (and especially from your top speed as friction losses are exponential) and how much you avoid braking. That's why I suggest that eliminating recoverable output from the energy output indicator would actually indicate efficiency and thus enable a regular driver to drive more efficiently. If you see that your wasted energy goes up every time you speed up, but it doesn't change as much when you vary speed quickly vs. doing it slowly, you will focus your driving habits on reducing top speed and avoiding braking.
     
  15. NET

    NET New Member

    Joined:
    May 22, 2013
    Messages:
    2
    Location:
    New York
    The Model X will have the option of two motors for AWD. Tesla only uses a single gear and should try and revisit multiple gear shifting. The front would have the lower gear and back a higher gear.[FONT=&quot] At highway speed the rear would take over hopefully saving some electrons.[/FONT]
     

Share This Page