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First road trip charging loss

Discussion in 'Model 3: Battery & Charging' started by Sweet OJ, Jun 14, 2018.

  1. Sweet OJ

    Sweet OJ Member

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    I just took my first road trip from Orange County, CA to Yosemite. Overall I was pretty pleased with the experience, the quiet cabin, the ability to pass instantly, the route planning by the navigation etc. I will also admit that this was my first trip with an EV of any kind, so I acknowledge I have some learning to do about how to best plan out a trip, and drive more economically while not having to go so slow that the trip takes significantly longer than it would in an ICE car. Anyway, the reason I'm writing this is I'm pretty disappointed in how the battery seems to have responded to a 720 mile round trip. I charged to approximately 95% immediately before the trip - at that time my estimated range was 295 miles. So, with a supercharge about 1/2 way through the trip distance wise in Bakersfield, we arrived at Fish Camp just outside of Yosemite with only 18 miles of juice left. I knew that it's best not to run the battery below 10%, and that I ran it to about 6% here. That was not my intention, but the car's estimation was initially that I would be able to go all the way to my destination which was about 35 mountain climbing, windy miles further than the last supercharger on the way. I figured I was totally safe to get to the next supercharger without going below 10%, but with a pretty aggressive driving style and the uphill climb, I didn't get anywhere near the expected range. Anyway, without boring everyone with every little detail, it appears that my new 90% charge range is down from 282 miles to 274 miles after the trip. I'm not really angry about this, but I am pretty disappointed if this is a permanent loss this early in the battery's life. I only charged above 90% ONCE, and only went below 10% (or even 25% for that matter) once. My question is this - is a 2.5% battery loss a normal price to pay for going up to 95%/down to 6% one time? If so, would I be better off charging to 100% to make as sure as possible that I don't go below 10% again? This isn't always fully in your control. Either way, it just seems like there is a rather large price to pay for driving an EV on a road trip. If the choices are drive much slower than you would in an ICE vehicle or risking lose a chunk of range permanently, both of these options are pretty bad IMHO.
     
  2. jamnmon66

    jamnmon66 Member

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    Try charging to 100%, running the battery as low as you dare (I went to 6 miles of range left). And then charge it to 100% again (without stopping). This will recalibrate the estimate. My 100% range estimate went from 311 to 315 when I did that.
     
  3. eprosenx

    eprosenx Member

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    0% charge is not 0% on the battery.
    100% charge is not 100% of the battery.

    Tesla already has safety margins built in to what they provide the "user" access to.

    I would say a single "high" charge and a single "low" charge should not in any way materially impact the battery life.

    Perhaps others here can comment on the range numbers you are seeing. I would say perhaps the car adjusted your estimate based on your learned driving style, but some have said the cars don't do that? Also, perhaps it has to do with outside temps?
     
  4. jamnmon66

    jamnmon66 Member

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    BTW, the problem with going close to 0% or 100% charge levels is the amount of time spent at those levels not so much the fact that you did so. That's why it's recommended to charge to a lower level for daily driving and only charge to 100% right before you start a road trip. I typically charge to 70-80% nightly which rarely falls below 30% by the time I'm done for the day.

    It's possible that you have a bad battery but I really doubt it. The range issues sound like the result of spirited driving mixed with an uphill climb. If you were using heat or AC, that would affect it too. Something to get used to. The miles remaining estimate is based on the EPA rating of 310 miles on a full charge and does not adjust for driving conditions. Pay attention to the wh/mi on the odometer. Lower=longer range. Somewhere around 250 wh/mi would be equal to the EPA rating of 310 miles. If you're up to 300 wh/mi, that should be around 250 miles of range (if my math is correct).

    Try the recalibration procedure and see if it fixes your other issue. Just don't let it sit at 100% for a long period of time.
     
  5. Rocky_H

    Rocky_H Active Member

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    Yes & No, respectively.

    Now for @Sweet OJ 's questions:
    There are a few things that are always new to new EV drivers. You're looking at the "rated miles" number, and then wondering why you don't get that distance. Well, the word "rated" there refers to the EPA ratings for efficiency testing. You know how those EPA gas mileage ratings are! They are for pretty calm, leisurely, slow-ish driving, which most people don't do. I'm pretty sure you were going faster than 65 mph on your trip. That's fine, but understand that you're going to go through those "rated miles" faster than 1:1 with your real miles of distance because you're going faster than the EPA procedures account for.

    And that is not a real permanent loss of the battery capacity. You are definitely not the first to ask about that--it comes up frequently. Every Tesla car shows something similar to that in the first few months. It's usually somewhere around 5-7 miles that appear to be "lost". That's an artifact of measurement inaccuracy generally. Measuring the amount of energy in a battery isn't as easy or precise as just looking at the amount of flour in a measuring cup. There are some processes that are trying to estimate it from input and output, but it's trying to figure out from some averages across thousands of cells wired together, etc. There are those steps you can do, as mentioned above, by running the battery nearly empty and then nearly full, which will kind of re-teach it a more accurate measurement. You can do that if you want, just to get the warm fuzzy of getting the reading more accurate again, but it's not related to the health or capacity of your battery, so it's not anything you need to worry about.
     
  6. Sweet OJ

    Sweet OJ Member

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    Thanks everyone - I feel better. My interpretation of this new information that you've shared is that my newly perceived driving habits (my car's AI now "knows better" it doesn't get the advertised range when I drive like I have recently. So it's estimating that I won't be able to drive as far without charging again, which would be accurate if I constantly took road trips (luckily I do not). But again, thank you everyone for taking the time to help me understand!
     
  7. jamnmon66

    jamnmon66 Member

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    One more thing... to let you know where my math came from, it's been reported that the M3 battery is ~75-80 kwh. I'm assuming that it's a little over 75.

    Each 1 kwh is 1,000 wh. So, when you get 250 wh/mi, that's 1,000 wh (or 1 kwh) for every 4 miles (250x4=1,000). Do that 75 times (for the available 75 kwh) and you would have driven 300 miles. If the battery is just over 75 kwh then 310 miles of range is about right for 250 wh/mi. There are some assumptions and rounding here but it's probably pretty close.

    I wish they would use mi/kwh rather than wh/mi because it would be a much easier transition for us coming from mi/gal for a gas car. Incidentally, 250 wh/mi is the same as 4 mi/kwh.
     
    • Like x 1
  8. jamnmon66

    jamnmon66 Member

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    You bet! :)
     
  9. Rocky_H

    Rocky_H Active Member

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    Well, we're all kind of U.S.-centric here, aren't we? The metric rest of the world has been using that consumption type of number all along. They do liters per 100 km, so it is just like watt hours per mile.
    I think the pretty good reason not to is to actually use the numbers that have more granularity. People seem to space out and go to sleep on things that come after a decimal place. We're OK talking about 260 or 270 or 280 whrs/mi, but would people say 3.84, 3.70, or 3.57? Usually not. They would just say it's about three and a half or four.
     
    • Like x 1
  10. snakeopus121

    snakeopus121 Banned

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    Welcome to the world of Tesla and EV ---- things are never as they seem
     
  11. snakeopus121

    snakeopus121 Banned

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    [​IMG]
     

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