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Road trip buffer

Discussion in 'Model S: Battery & Charging' started by Max*, Sep 7, 2015.

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Percent buffer for supercharger road trips?

  1. 0%-5%

    2 vote(s)
    2.2%
  2. 6%-10%

    18 vote(s)
    20.2%
  3. 11%-15%

    23 vote(s)
    25.8%
  4. 16%-20%

    27 vote(s)
    30.3%
  5. 21%-25%

    15 vote(s)
    16.9%
  6. 26%+

    4 vote(s)
    4.5%
  7. I don't take road trips, but I like to vote!

    2 vote(s)
    2.2%
Multiple votes are allowed.
  1. Max*

    Max* Autopilot != Autonomous

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    When you take a road trip, with a supercharger stop(s), what's the usual buffer you leave yourself (from the trip tab) to arrive at the next supercharger/destination.
     
  2. dweeks

    dweeks Member

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    6-10% on routes I know. If I was off my beaten track for the first time, probably 10-15%.
     
  3. Max*

    Max* Autopilot != Autonomous

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    Do people leave more of a buffer in the winter over summer?
     
  4. Amped_up

    Amped_up Member

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    0-5%. I live life on the edge.
     
  5. Vger

    Vger Active Member

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    That is about my strategy as well. Unexpected headwinds can still kill a predicted 10% buffer pretty quick. I will cut it close (5-10%) when I am confident of the conditions and know the route. If I am not in a hurry and in new territory, I often shoot for 15% or even 20%.

    As Jack Bower pointed out at TMC Connect 2015, you have to watch the prediction in the early stages of a leg. It is often quite variable and unstable early on, and then gradually settles down during the final 50-80 miles of a leg.

    - - - Updated - - -

    I used to, but learned my lessons! On one trip, my battery was out of calibration, and it went from 2 miles RR to shutting down with no in-between! We literally pushed the car into the supercharger. My wife has still not forgiven me!

    You also do not contend with mountains or deep cold down there. :wink:
     
  6. Ugliest1

    Ugliest1 S85: "Sparky"

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    I voted 11-15% but sometimes only leave 5-10%. My biggest problem with superchargers is the car is done before we're ready (I guess we walk slowly), so I end up with a 30%+ buffer!

    Haven't done much in the really cold so far, if/when I do that buffer will be going significantly up (30% minimum) until I get used to what happens.
     
  7. mknox

    mknox Well-Known Member

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    I said 16-20%, but that's in the summer. I would leave more than that in the cold of winter.
     
  8. KJD

    KJD Member

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    I voted 16% to 20% but this will vary a lot according to how well I know the route and how many alternatives there are along the route. I also like to start the day with a 100% charge, because if you charge while sleeping it does not cost you any time and gives you more options for the next day.

    I also like to plan a lunch break at a SC and often take extra time to read and write emails or read TMC while the car charges. If I am on vacation, I try and keep a relaxed pace. It is much less stress that way, compared to worrying about making it to the next charge location.

    If after all that you still end up cutting it close on range, just drop the speed 10 mph and the battery will last much longer at a slower speed.
     
  9. HankLloydRight

    HankLloydRight Fluxing

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    I said 20-25% because I like to have extra buffer and I like to drive fast and not worry one iota about range.

    Also, once I got caught in a massive backup on the NJTP heading north into NYC and that sapped all of my buffer, I had to find alternate, slower than highway routes, but at least it was moving. Then I hit a detour around the route I wanted to take.. I think I arrived home with about 10 miles left. After that, I always spend an extra 5 to 10 minutes at the SC for just a little extra buffer.
     
  10. ChadS

    ChadS Petroleum is for sissies

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    There is a lot of stuff the energy estimator doesn't know - how fast you will drive, headwinds, weather changes, detours, etc.

    Add to that the fact that all possible EV drama happens at the bottom of the battery, and I just don't go there. I used to always have a 50% buffer, but since the energy estimator takes some things in to account that that used to cover (like elevation gain) I no longer feel the need for that much. I try to always get at least a 20% buffer; and more is better if I'm not in a hurry.
     
  11. cpa

    cpa Member

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    I voted 11-15%, as most spacings are <150 miles. For longer routes, however, I charge to a 16-20% buffer.
     
  12. Khatsalano

    Khatsalano Member

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    San Mateo, CA
    Same.

    For battery health, I try to use the 20-90% SOC range for all of my distance driving. But for very long road trips, I've gone down to 5% before when confident (like skipping Corning SC, from Shasta to Vacaville SC because it's mostly downhill and with the wind that day).

    - K
     
  13. martinwinlow

    martinwinlow Member

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    5-10% is my usual margin (and I have a MS60 - shouldn't we all be saying what pack size we have? - maybe most are at least 80s...?) but unlike Jack, I will monitor the difference between range remaining (RR) and distance to go (DTG) all the way through the trip... And this is the important bit - if that difference begins to fall then SLOW DOWN, say 5 mph and then monitor it for 10 minutes or so. If it steadies, then fine, carry on at that speed. If it continues to reduce, then you must slow down some more and so on until you either arrive or the difference stops reducing. This way it will be nigh on impossible for you to run out of energy.

    Conversely, of course, if you find the difference between RR and DTG is going up, then you can afford to go a bit faster. Same rules apply. Bear in mind, however, that ideally, you want to arrive at your next SuC stop with as little RR as possible as, that way, the charging time is minimised for your next leg. This may not be the best strategy for battery longevity, of course.

    One last issue is the affect of elevation change on RR. After a recent 1000 mile round trip to Scotland, it was quite noticeable that the RR started falling significantly as I climbed up into the Highlands. However, coming back out of them the RR increased again. Over 50 miles between going into the high ground and coming out again I lost and regained about 20% of my RR (the max increase in elevation was ~900 feet). MW
     
  14. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    When posible, 20% or more. An unexpected head wind can really eat range.
     
  15. Max*

    Max* Autopilot != Autonomous

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    I try to hit 6%-10% buffer, and we try to maintain 70-75mph speeds. At those speeds, the trip tab doesn't really decrease/increase between long SpC legs (70D, if it matters)

    The "issue", is that for example heading home last night, stopped by to get a charge. Only needed about 10-12mins charge to get home, but I couldn't get my kids back in the car for another 20mins (ended up at the SpC for ~30mins, instead of 10), so I had a much bigger buffer than intended. Also, on longer roadtrips, we try to plan meals around the longest SpC stops, so often times we end up with a much higher buffer than intended too.

    So far, only taken summer trips. In the winter, I need to see how accurate the trips tab is, maybe I'll stick with 6%-10%, maybe I'll bump it up a bit... (I'm also on the east coast, and for the trips we take often, we often skip several SpCs, so I know if I see my buffer go way down, I can stop earlier)
     
  16. mknox

    mknox Well-Known Member

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    One of the things that drives me nuts about the trip planner is that I can never seem to come in along the projected line. I am always below. I can take a 100 mile trip, average around 280 Wh/mi, but my "actual" line will be below the "projected" line on that graph every time. When the feature came out it was winter (and I was WAY below the line) and I assumed it would get better in the summer... but no. I am wondering if it is assuming I have a brand new battery pack when in reality I am seeing about 9% degradation at this point in my ownership.
     
  17. Max*

    Max* Autopilot != Autonomous

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    That is very odd. For my it's the opposite. I'm always above the line, doing 70-75mph. If I do the speed limit (55mph-65mph), I'd be WAY over the line.

    Range mode on, AC at 67F, 4 people in the car (2 kids though) + stuff. It was warm though, probably 80F.

    This weekend (skipped like 3 SpC along the way, was supposed to arrive at 0%, arrived at 7%, 200+miles). There were parts of the trip where my wife did some... "spirited" driving too, and still arrived with 7%.

    20150904_231417.jpg
     
  18. Rocky_H

    Rocky_H Member

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    Heh, yeah, I don’t ever want to be “that guy” who ran out of power, so I do leave margin and drive cautiously, so I don’t have to worry about it.
     
  19. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    That doesn't jibe with my experience in both the S85 and P85D: I consistently arrive with more range remaining than the trip planner estimated.

    I voted 11%-15% buffer; it used to be 20% until I got comfortable with less.
     
  20. mknox

    mknox Well-Known Member

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    Beats me why it works that way on my car. I will often see myself trending below the line within the first mile or two. And I do not tend to drive fast or aggressively, and it does show in my very good Wh/mi numbers.
     

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