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Feature request: A smarter energy usage graph

Discussion in 'Model S: User Interface' started by nikita, Sep 21, 2013.

  1. nikita

    nikita Member

    Joined:
    Aug 21, 2013
    Messages:
    8
    Location:
    K-W, ON
    I find the energy usage graph very noisy, especially in city driving. It drops down whenever you stop at a traffic light and jumps up when you accelerate from a complete stop. This creates a ton of spikes which hide the bigger picture of your energy usage.

    When you accelerate from 0 to some speed the graph shows that you spent a ton of energy just to travel a few meters. But that’s not true. Most of the energy was converted into kinetic energy (equal to m*V^2/2).

    When you are gliding, the energy graph shows 0 Wh/km (Wh/mi). But that’s not true. You are using up your kinetic energy and as a result you are losing speed.

    When you are using regen, the energy graph shows that you are gaining energy back(goes into negative). But that’s not true. You are converting kinetic energy into chemical energy of the battery and this process is it is not 100% efficient.

    When you are braking with regular breaks, the graph shows no energy used. But in fact your brakes have just converted all the kinetic energy into heat.

    A possible solution is to take the kinetic energy into account and display the changes in the battery energy and the kinetic energy. The change in the kinetic energy is: m * (V1 ^ 2 - V0 ^ 2) / 2, where m is the mass of the car, V0 is the speed at the start of the time interval and V1 is the speed at the end.

    The exact mass of the loaded car is not known, but it can be estimated to be the nominal weight of the car plus one weight of an average person or two - if the passenger seat sensor detects a passenger.

    It may also be useful to take into account the changes in the gravitational potential energy: m * g * (h1 - h0), where h0 and h1 are the elevations at the start and the end of the time interval. The change in elevation could be retrieved from the GPS or from Google Maps (https://developers.google.com/maps/documentation/elevation/). The elevation changes would be useful to smooth out local changes. But if the whole trip starts and ends at very different elevation levels then this feature may lead to overly optimistic (going uphill) or pessimistic (going downhill) range projections. So this part may need to be optional.

    A graph that takes the kinetic and the potential energy into account would be less noisy and more informative. It would be much easier to see the effect of changes in factors that are under the driver’s control: average speed, A/C or heat usage, tire pressure, etc.

    I don't think I have permissions to add a poll, but I do want to get sense of whether you would like this feature or not. So please use the 'Rate This Thread' link at the top.
     
  2. Argelius

    Argelius Member

    Joined:
    Jun 8, 2013
    Messages:
    239
    Location:
    Palm Springs, CA
    I generally agree. I think the energy graph could use some additional thought and a more creative way to depict the information.
     
  3. steve841

    steve841 Active Member

    Joined:
    Jan 17, 2010
    Messages:
    1,397
    Location:
    Ft. Lauderdale, FL
    By and large .. yeah, they need a redo of the energy usage graphs ...

    But, I feel too many people are too focused on getting or stretching every last electron out of their car...

    Makes me wonder if they are obsessing over energy usage rather than enjoying their car.
     
  4. Raffy.Roma

    Raffy.Roma Active Member

    Joined:
    Jul 22, 2012
    Messages:
    3,209
    Location:
    Rome (Italy)
    @nikita

    IMO the whole elements affecting a complete energy calculations are too many (Height of the car with respect to sea level, mass, speed, losses). I don't see the point to develop such a complex energy calculation device on the Model S. Electric cars already jump the second principle of thermodynamics that on the contrary ICE cars have to respect and for this reason are by definition much more efficient.
    IMO it would be much more effective if Tesla offered as an option a solar power system. This way Model S drivers would enjoy the taste of driving at zero cost.
     
  5. nikita

    nikita Member

    Joined:
    Aug 21, 2013
    Messages:
    8
    Location:
    K-W, ON
    I do enjoy the car, but driving itself does not occupy 100% of my brain cycles. So I like to play the game of minimizing energy usage. It's just like any other game we play: Games We Play - YouTube
     

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