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Failed range calculation left me stranded

Discussion in 'Model S: Battery & Charging' started by Twiddler, May 17, 2018.

  1. Rocky_H

    Rocky_H Well-Known Member

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    I would just bring up two specific factors that relate to that:
    1) That "6" miles is about 2 kWh. That's about 2-3% of the battery, which is expecting more precision in this than in most devices we use.
    2) It's not just one battery. As was mentioned earlier, there are thousands of cells in it, and there can be a little bit of imbalance of the energy and voltage in them, where some are a bit lower. Lithium ion batteries suffer severe irreversible damage if they get actually drained to dead. They are shutting off the car just before this point where they would be killing some of the battery cells by overdraining them. So if they were to do this, to give people those extra few miles worth of energy when they really do need to be cutting off the pack, it would kill a few battery cells. And then the next time they did that, it would kill a few more. And you think people are worried about battery degradation now? This would be much faster, destroying small pieces of the battery at a time, before their useful life expectancy. And all that, just because people can't plan for some single digit amount of miles? They are helping you by not letting you destroy your battery.
     
    • Informative x 1
  2. cybergates

    cybergates Member

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    #82 cybergates, Jun 5, 2018
    Last edited: Jun 5, 2018
    I've gotten as low as 5 miles, while driving to a SC but I was wary. This is scary to know that the gauge is not that accurate. I would assume there should be some buffer. Mine seems to be calibrated well but I wonder if high mileage will make it more inaccurate or waht? A scarier thing is I was at a restaurant recently (twice this happened) where it shows 33 miles left, no problem SC is only 5 miles away - come back to the car and the range has drastically dropped to 15 or so (always connected off and energy saving on)

    Did OP state which year car or how many mileage total on the battery?
     
  3. kavyboy

    kavyboy Active Member

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    Rated range is the range the EPA says you would get for the given amount of energy in your battery under certain conditions (speed, temperature, etc.). Driving 90 MPH is not one of those conditions.
    By comparison, let's say your ICE's Monroney sticker says you'll get 40 MPG. You have a 20 gallon tank. Fuel gauge says 50%. That should get you 400 miles to City X. So you take off through the mountains at 90 MPH with the AC blasting into a headwind and rain. You are not going to get 400 miles on that tank. You're car is still rated at 40 MPG, but you're burning gas faster than the conditions that led to the 40 MPG value. The fuel gauge isn't wrong or recalibrating, it is simply showing dropping levels due to accelerated drain. There's no fancy calculation or recalibration. Half way there, you're thinking "Odd, I'll need to stop for gas long before I make it to City X", and you modify your refueling plans en route.
    Same thing in a Tesla. You're nav gave its best guess as to how much charge was needed. Your consumption was higher than expected and it modified its refueling/consumption plans en route.
     
  4. stallhorn

    stallhorn Member

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    Lots of people die due to fuel exhaustion in small airplanes because they cut it too close. Running out of fuel is just an inconvenience in cars, but it can cost one their life when they run out of fuel in an airplane.

    But people still do it..

    Having reserves is a good thing both on the ground and in the air.
     
    • Like x 2
  5. cybergates

    cybergates Member

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    agree we don't want this kind of battery damage but all they have to do is simple set 15 miles = 0 in the range bar in the dash

    also if I get that low I use the main screen predicted range too as that gives u also a realistic idea on how u drive the car.
     
  6. Rocky_H

    Rocky_H Well-Known Member

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    No. I covered that already:
    https://teslamotorsclub.com/tmc/posts/2748526/
     
  7. Testwa

    Testwa Member

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    I agree, Tesla should play it more save to avoid people get stranded. If it is now known that people got stranded with ~10miles left, than Tesla should set this as the new Zero value. Then people would be more aware of the risk if they go below 0. Not necessarily a consequence but at least to think about is that the range (also official EPA range) should be reduced by these 10miles.

    Also I agree to make the car more sluggish when being in the low range. ICE don't have it but would be nice for EVs to avoid a more or less sudden shutdown. In principle Tesla has this feature, I think they just need to improve it and bring it more towards the safe side.
     
    • Like x 1
    • Disagree x 1
  8. David99

    David99 Active Member

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    There is a handful of people that happened to. I can only remember 4 cases total. Two of those pushed it hard towards the end. One was Tesloop and they got a new battery for free. I don't think Tesla should reduce the range artificially an all 200k cars because of a tiny amount of exceptions.
     
    • Like x 4
  9. bmah

    bmah Moderator, Model S/X, California Forums

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    Moderator note: Snipped an inflammatory comment.

    Let's please try to be civil.

    Thanks,

    Bruce.
     
    • Like x 2
  10. mhan00

    mhan00 Active Member

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    As others have pointed out, if they did that then there would be people who would start expecting that 15 miles below zero every time and start driving below zero more often, and subsequently complain if they only got 10 miles below zero one time instead of the expected 15. Better for Tesla to tell drivers that there is a 1-2 percent margin of error for the battery indicator and to plan to charge accordingly.
     
    • Like x 1
  11. logan

    logan Member

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    My comment of “what do you expect from people who have had too much Tesla Kool-Aid ;)“ was clearly tongue in cheek and in support of OP who faced multiple — quite frankly — obnoxious and rude replies.
     
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  12. X Fan

    X Fan Supporting Member

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    Left earlier than planned the other day and didn’t get a full charge for my beach trip.

    Got to OIB the other day with 10 miles left. Sweaty armpits for sure....

    At 6 miles, I’d just think of the famous Eastwood “Dirty Harry” line: “Do I feel lucky”?
     
  13. David99

    David99 Active Member

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    The battery icon goes to orange/yellow when it's below 20% and to red when it's below 8%. If you are using the navigation system you get plenty of warnings right from the start. No amount of warnings is going to make a difference to those 3 people that had their car shut down at 1 or 2% because they clearly didn't pay attention to those warning. There is no problem. We don't need a fix.
     
  14. bmah

    bmah Moderator, Model S/X, California Forums

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    You're right, I completely misinterpreted your post. Bad call on my part. Apologies for moving it...I've moved it back (I think).

    Bruce.
     
    • Like x 2
  15. buttershrimp

    buttershrimp Click my signature to Go Mad Max Mode

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    Dang.... you must be pissed! That would suck for sure. I'm curious, I've driven past the 0 point, but I think I was able to do it because I didn't get above 20 mph.

    As for Porsche..... you should sleep on it. I'm pretty sure buying a "Taycan" will cause you to lose dignity.
     
  16. alloverx

    alloverx Member

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    This (remaining usable battery charge) sounds like a technical problem that should be solvable. Perhaps a more technical display from the BMS would help?
     
  17. Astraviel

    Astraviel Member

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    #97 Astraviel, Jun 9, 2018
    Last edited: Jun 9, 2018
    I never allow my battery to go below 10% if I can help it. My very first car was a Honda Civic and one time I had planned a hiking trip, but in order to do that I had to drive up a mountain. I distinctly remember I had 108 km at the base, and by the time I drove 10 km up elevation to the parking lot, I had 5 km range left. Luckily, I was able to put my car in neutral and coast all the way down and arrived at a gas station with 0 km left on the gauge for at least 5 minutes of driving on the return trip. I got arrogant after that and drove to a place called Merritt, BC a few months later, skipping gas stations along the way thinking I could get to it with just barely enough range left, but once I got to 2 km left and 5 km from the nearest gas station, my car shut down.

    When I bought a Porsche 911 Carrera GTS a few years later I vowed not to let something like that happen again. There are too many variables for the gauge like elevation and acceleration and stop lights and so forth. A dehydrated person is not a happy person. Cars are the same way. Treat your car like it's your baby.
     
    • Like x 2
  18. Electric700

    Electric700 Active Member

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    #98 Electric700, Jun 12, 2018
    Last edited: Jun 12, 2018
    To the OP, did you try charging to 100% and after the charge completed, drive it within 15 minutes (for battery health)? This might help with the issue, though there has been some question about this among members here. I generally try to charge to 100% once a year to balance the battery, though there's also a debate about the need for that as well.

    I wouldn't give up on Tesla just because of this issue. It could happen with any car, as others have mentioned. It's always better to be safe and charge extra if you think there's a chance you will get to your destination with the battery having less than 5 - 10% of its energy remaining.
     
  19. North75

    North75 Member

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    When I was in college I managed to run my car out of gas exactly when I parked in my driveway. I knew it was low but didn't realize it was empty. When it wouldn't start the next time I tried to drive it, I assumed that something was broken. I then proceeded to leave it in my driveway for a couple of weeks because I didn't need to drive anywhere.
    I can't remember why, but one day I decided to put some more gas in the tank. It started right up and was totally fine.
     
  20. Charliek

    Charliek Member

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    Hi I use percentage for this exact reason. You will see many different miles estimates and if you go to percent you will see it says 1% most people won’t try running any apps on a phone or try to hav a long conversation at 1 percent. And even Apple has had issues where voltage shift with temperature had the phones shutting down at 4%. It would be like saying oh I have 2 more minutes if ap time and then it dies early,. Use percentage and you won’t get down so far. Also trust the yellow warning is I think at 10mpercent and red is at less than 7 or 5 percent. (that is in a 90D) percentage is relative to the size your battery is and therefore miles but not to how much you have left , that is determined my your running wh/mile. If you are going to need to cut it close.adjust energy meter in real-time or 5miles average versus 30mile average to see how much you are chewing up so you can optimize all loads if you are that close. me, I Start find a charger at no lower that 10percent. I went to 3 percent and that freaked me out. Other wise I get range anxiety pretty fast.
     

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