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Trip Planner charge level projection improvements

Discussion in 'Model S: User Interface' started by bob_p, Feb 1, 2016.

  1. bob_p

    bob_p Member

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    Took the first trip with the 7.1 software this weekend.

    On one leg of the trip, the trip planner was way, way off on projecting charge. We left the supercharger with more charge than the software advised. We were driving at posted speed plus 5 MPH, and watched as the projected charge level for the next supercharger quickly started dropping.

    The software release notes indicates the software is supposed to issue advice on slowing down in this case - to ensure you don't use charge too quickly to reach the next charger. We never received that notice, though that could be that when the projected charge level reached 10%, we started taking corrective actions on our own.

    We had to slow down 20 MPH for extended periods before we could start regaining charge - and building back some cushion - and ended up driving 10 MPH under the speed limit for most of that leg.

    Temps were in the 60-70s, sunny, wind may have been behind us - and traffic was not too heavy so we could maintain a constant speed. Other than elevation change (Houston to Dallas), there wasn't an obvious reason why we were burning through charge faster than the trip planner projected.

    Coming back, the trip planner was more accurate - and though we used a little more charge each leg than was projected, we never had to reduce speed.

    We typically leave the charging station with at least 25% of projected charge at the destination - giving us some cushion. And while driving, we prefer to have no less than 10% of charge at the destination, just in case there is an unforeseen challenge with the supercharger (real-time status of the chargers would be very useful!).

    Suggestions:

    First, there should be some settings for the trip planner to indicate likely speed (relative to posted speed limit) and desired charge level at the destination. This should provide more realistic charge projections and charging time estimates.

    Second, if the projected charge level drops below the desired charge level, a message should be displayed - and the dashboard should show the projected charge level - making it easier for the driver to monitor the charge. It's better to warn drivers about a potential charge concern as early as possible - because the longer the warning takes to display, the greater the correction that may be needed. Even though we were monitoring this early - we still had to drop 15 MPH below the posted speed limit (and most cars were driving 5-10 MPH above the posted speed limit).

    The above changes should help - plus the algorithm for predicting charge uses evidently still needs some improvement.

    The other interesting thing I noticed on the trip was that during one leg of the trip - the projected charge at the next supercharger was oscillating between 25-35% - periodically getting some large (5%) jumps up or down. That level of jump indicates the software isn't doing a very good job at estimating projected charge level.
     
  2. iffatall

    iffatall Member

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    The "reduce speed" message pops up when the projected charge remaining at the next planned supercharger stop drops to 5%, and not before then.

    From what I have observed, the estimated charge remaining is not too far off when I drive at speed limit +5 MPH. However, when there are mountains on the way, the projected charge remaining drops drastically on your way uphill. It does come back close to the original projection though, once you are back downhill. I agree it is nerving to see the drastic drop. My guess is that the planner takes the net altitude difference between src and dstn to make the initial projection, but doesn't really do anything to track the ups and downs en route. Once the driving begins, instead re-computing the projection throughout, it simply compares the real energy usage with the average energy usage it expected when it made the original projection. I think recomputing every few minutes, would keep it more accurate, but don't know if there are any downsides to it.

    Also. the planner does not take temperatures and winds into consideration, and we should have additional buffers for each.

    The projection fluctuates up and down a lot at the beginning of your segment, and then kinda settles around half way through. To be safe, I always supercharge for an additional 15 mins past when it says it has sufficient charge to continue trip. So far, I have observed 15 mins is being a bit too cautious, and 5 mins should do. But I am just too risk averse to take a chance.
     
  3. SomeJoe7777

    SomeJoe7777 Marginally-Known Member

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    I did Houston to Dallas last week, and was fighting a 15+ MPH headwind the entire way. Couldn't get below 350 Wh/mile even at 65 MPH (10 under), and that was in an 85D with range mode on.

    Winds will definitely cause problems. There is a link for a Tesla-specific web page that will show you your headwind/tailwind:

    http://matesla.ca/headwind.html

    Add that as a bookmark to the in-car browser and refer to it often when on road trips.
     
  4. rxlawdude

    rxlawdude Member

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    If you start navigation to a destination, then select the "Trip" tab on the Energy App on the 17" screen, you'll note the sawtooth graph. That indeed anticipates altitude changes and is probably the best tool to monitor your energy remaining. In fact, it's kind of fun to look at where the projection spikes up (due to a downhill segment with regen) or rapidly falls (due to an uphill with significantly higher energy use).
     
  5. S4WRXTTCS

    S4WRXTTCS Active Member

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    I see no reason why they couldn't update the trip planner to account for wind. They already account for elevation change and temperature.
     
  6. chargeshare

    chargeshare Member

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    Which is correct?
     
  7. BertL

    BertL Active Member

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    Tesla does not presently account for existing or projected weather conditions. Could they? Sure. But they don't.
     
  8. bob_p

    bob_p Member

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    I sent an e-mail to Tesla about the poor estimation on our Friday trip. The initial response was to use display the energy graph on the dashboard so I could monitor the energy usage and that if I averaged 300 Wh/mi, I'd be at the rated range. After several exchanges, my message was forwarded to their 2nd tier support.

    The purpose of the range estimate by the trip planner is to have the software do the hard part and help the drivers control energy consumption and safely get to the next charger. 5% of range left is cutting things pretty close - I'd be more comfortable with 10% - something that should be a setting for the driver to select - same with the relative speed to the posted limit which the trip planner should be using for estimates.

    Tesla should be collecting a lot of data on how well the trip planner is working - and should be able to do much better in managing this.

    As a driver, what I would like to see is for the software to give me an early enough warning to allow me to drive as close as possible to the posted speed limit - and not have to drop 15 MPH below the posted limit in order to reach the next charger with the desired cushion (in case there was a problem at the charging station).
     
  9. Max*

    Max* Autopilot != Autonomous

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    I thought it was actually 7%. When the color switches from green to yellow.
     
  10. iffatall

    iffatall Member

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    5% is based on my observation. I don't know if the threshold is different for different conditions though.

    - - - Updated - - -

    True, the graph shows ups and downs. My comment on the planner not taking ups and downs en route under consideration was for the expected charge remaining at the end of the segment metric only. I know it is very odd that it knows the ups and downs, yet, doesn't take them into account when recalculating projected charge remaining when you actually go up or down hill.

    As I mentioned earlier, I could be wrong, but I could not come up with a better explanation for the drastic drop in projected leftover charge at the end of the segment when going uphill, and then coming back up to safer levels when going downhill.

    I have only had a few long trips recently, so it is indeed possible there were other factors that I have failed to notice.
     
  11. garygid

    garygid Member

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    The Estimated Energy Remaining graph (which takes elevation into account) on the Trips tab
    under the Energy Usage Icon ... is one of the most useful features of the Tesla "navigation"
    system. As you drive the Route segment (to the destination, or to the next Supercharger),
    the graph shows how you are doing with respect to its original estimate, and it continues
    to display an updated estimate for the expected energy remaining at the end of that trip
    segment. Try having it on the lower half of the touchscreen as you drive. I have found
    that it gives very helpful feedback.

    This graph is also helpful during charging, showing the expected energy usage for the
    next segment of the Route, with the estimate rising in real time as the car charges.

    Since headwinds, battery temperature, road conditions (rain and snow), and energy
    usage inside the car/cabin all need to be considered, this Trip Graph helps you
    learn how these factors are affecting your energy usage in a very understandable
    way.

    At least, I suggest giving it a try, even in ideal conditions, to better evaluate you
    own driving style.

    Cheers, Gary
     
  12. Gunner

    Gunner Member

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    Same As We Used to Use Use In Long Overwater Flight

    The Trip Planner is, as said above, a very good tool.

    Perhaps I'm showing my age but this is exactly the system we used to use on our long overwater flights.

    We called it our "Howgozit" chart.

    For those interested, an aircraft's range is dramatically dependent on maintaining a constant angle of attack between the wing and the relative wind.

    In the beginning of a flight the aircraft is heavy and a higher power setting is required to maintain the desired angle of attack while later as fuel is burned off the aircraft's weight is reduced and the power and hence fuel consumption per distance traveled can be reduced while still maintaining the desired angle of attack. It was routine to start a transatlantic flight with an indication that the fuel reserve would be negative and we were destined to get our feet wet.

    Only by plotting the actual progress against that predicted on the Howgozit curve could one be assured the flight was proceeding according to plan and we would, indeed, reach land with some fuel reserve.

    I use the Tesla trip graph the same way. However, I have found it useful to, if my driving parameters have changed, reinitiate the destination in the nav unit which then updates the trip graph predictions based on my current driving parameters.

    Just my thoughts
     
  13. S4WRXTTCS

    S4WRXTTCS Active Member

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    Someone can correct me if I'm wrong, but the trip graph under the energy app DOES account for temperature when it draws the graph. But, it's static temperature when it draws the graph. It doesn't take into account temperature changes that will happen as you drive to your destination. So there is no projected temperature taken into consideration.

    That doesn't really impact me because I don't live in an area that typically has drastic temperature changes.

    Taking into account wind should be priority number one on the trip planner. That would save a lot of people from the "surprise you now get to drive 20mph slower than anticipated" moment. There are lots of people like me who don't bother charging beyond 90% unless we really need to.
     

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