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The Rules of Model S Road Tripping

Discussion in 'Model S' started by Doug_G, Apr 22, 2013.

  1. electronhauler

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    Great post!
    I would add on the subject of drafting that a 3 second following distance should be observed. 1 second is less than most people assess and react (studies show it's closer to 1.5 seconds). Travelling less than 1 second behind another vehicle virtually eliminates any chance of dealing with an unexpected situation. (ADoNA: The Clear Leader in U.S. Driver Safety and Training - a Research Victory)

    On the range expectations, I have found that rain reduces range by about 15 to 20%. On a fossil fuel vehicle it increases fuel consumption by only 3 to 5%. I think this is due to the amount of water that gets moved by the tires as they rotate. Obviously this is more of a problem at highway speeds where each tire is displacing several gallons of water per second.
     
  2. Doug_G

    Doug_G Lead Moderator

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    On the subject of drafting, it is safer to do this on a big heavy truck. They can’t brake hard. Also a good use case for cruise control set to 1. It can react faster than you can.

    Heavy rain can be a lot worse than 20%, if the car is constantly plowing through standing water.
     
  3. sauce

    sauce :P

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    @Doug_G, I'd be careful with stating heavy trucks can't brake hard. Here in Canada they can have 4 and even 5 axles on their trailers and despite higher load tolerances than in the US, this allows for formidable stopping power EVEN if fully loaded. Better stability as well.

    I remember a situation a dozen years ago, having to stand on the brakes side by side with a 4-axle-trailer heavyweight in my '95 Accord and I couldn't outbrake the truck though it was fully loaded with gravel (that was scary as hell), so I would tend to believe a 1-second gap remains unsafe.

    That being said, I can say I wouldn't do it because of rock projections much before being worried about the tight gap. :D
     
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  4. vseno

    vseno Member

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    Wow, great. Owned Model S for 2 years now and learned a few tips here. Thank you.
     
  5. Brea_3

    Brea_3 Member

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    Great tips, thanks!
     
  6. gpetti

    gpetti Supporting Member

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    Hi Doug,
    I've read this a few times over the years - still very useful and I see you've updated it. Just one minor point I would suggest when driving AWD performance models. The range mode for these vehicles is MUCH more useful than for others. In Range mode, these cars favour the front (more efficient) motor and use something JB called "torque sleep" when at highway speeds. The help for Range mode implies this but I've actually verified it when in ludicrous plus mode which shows motor usage stats. In non range mode it definitely uses the rear motor more, though it may still torque sleep ultimately. I haven't done any scientific analysis on how much difference this makes but it is clearly more important than on cars that don't have AWD and presumably on cars that have the same motor front and rear.
     
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  7. Doug_G

    Doug_G Lead Moderator

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    Would be interesting to do an A/B comparison. I've found that even without using Range mode my newer 100D has much more range than my old P85, by a lot more than 100/85! More like double that difference.
     
  8. croman

    croman Active Member

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    I believe AWD cars always torque sleep regardless of Range Mode setting based on certain factors. Range mode only turns off DRL and adjusts HVAC consumption for cabin.

    That's why Range Mode seems mostly useless, I think it is. You might get 1-2% more range (which could be significant, but its still 1-2%). Aero wheels are far more effective though. DRL consumes next to nil energy.
     
  9. richlvt

    richlvt New Member

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    Well I just did my first road trip with my 2018 Model S 75D. Vermont to Richmond, VA then to Blacksburg, VA, back to Richmond and home to Vermont. Left Vermont it was 15 degrees. Realized would not make it to Newburgh Supercharger so stopped in Albany, NY. Cold weather really took energy I learned. Was a great road trip and can relate to a lot said in this blog, plus learned much from your advice. In Blacksburg found two level 2 chargers not working but finally found a Holiday Inn that was "public" with even a Tesla Plug. So again, learned to "charge" so can make it back to the Lexington Supercharger. All in all, was very nervous about the trip to start. As going along, charging, my tension lessened. Trip back on the busiest travel day of the year went very well. Superchargers were available. Stopped probably more then I should have but was as ease. Nice that you can see how many chargers are open at a location. Never had to wait. Tesla autopilot made the trip so much more relaxing, love the ride, the quiet, the sound system. Just a fantastic automobile.
     
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  10. sumitkgarg

    sumitkgarg Member

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    Question: To get the most from the regeneration going downhill, it is better to go at 35 m/hr or 55 m/hr?
     
  11. Doug_G

    Doug_G Lead Moderator

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    That’s not a simple question.

    Generally speaking, going slower is better because the aerodynamic losses are lower. That’s true at all times, not just on hills. Once you’re above about 20 mph, the faster you go the worse the energy consumption. It’s a big effect; slowing down just 5 mph can have a very significant effect on your range.

    Regen is way better than hitting the brakes, but it is worse than coasting. The drive train has a certain efficiency - there are always losses and that includes during regen. If you could go down a hill without using regen at all, while avoiding going excessively fast of course, that would be most efficient. So it’s probably a good idea to crest the hill at a low speed, and let the car speed up down the hill, and then use regen as needed to prevent the car from going too fast.

    To summarize... for best range:

    1. Drive slower
    2. Coast when you can
    3. Use regen when you need to
    4. Brake as little as possible
     
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  12. sumitkgarg

    sumitkgarg Member

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    So if you can avoid breaking, low regeneration setting is better than standard regeneration? That’s a great piece of info that I didn’t know.

    I was running really low leaving Dealth Valley last week trying to make it to Lone Pine SC. I tried going downhill at approx 35 m/hr but the estimated charge at destination kept going down. It was estimated at less than 5% at one point. It was a bit of a stressful situation with kids in the car, in the middle of nowhere at night and 0 cell phone coverage.
     
  13. ThosEM

    ThosEM Space Weatherman

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    How can regen be worse than coasting? The choice is between accelerating to a higher speed down a hill (which as you point out is always uses more energy), and harvesting energy with regen to keep your speed from increasing.

    You might ask, how can I use more energy when I'm coasting and no power is being used? Well, not harvesting available energy into the battery is the same as using that energy. Using it to accelerate the car increases drag and reduces the energy available for regen. The slower you go down a hill, the greater the regeneration power will be during the descent. Try it out: while going down a long steady hill on regen, decrease the setpoint speed a couple of notches. That will increase the regen power and vice versa.

    So I would revise your summary as follows:
    For best range:
    1. Drive at a slower, constant speed up and down grades (using cruise control or your foot does not matter)
    2. Regen will activate automatically whenever it can, and will be stronger at slower speed
    3. Think ahead so you can slow sufficiently with regen instead than using the brakes
     
  14. Doug_G

    Doug_G Lead Moderator

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    Like I said it is complicated.

    If you are going down a steep hill, and the car would speed up excessively, then it's clear you're going to lose a lot of additional energy to aerodynamic drag (not to mention going unsafe speed and/or getting a ticket), and harvesting energy via regen is the best solution.

    If the hill is just going down just enough to keep the car going a constant speed, despite the aerodynamic drag, then obviously you're going to use zero power traveling the length of the hill. The drive train efficiency is not a factor.

    In the real world, my advice would be to not worry about this too much. If you're concerned about range slow down 5 mph and turn on the cruise control. Oh, and if it's cold turn down the cabin heat and crank up the seat heaters.
     
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