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Should I charge to 100% (night before trip) if my first supercharger stop is only 80 miles away?

Discussion in 'Model S: Battery & Charging' started by GasKilla, Sep 30, 2016.

  1. GasKilla

    GasKilla No Gas Know Peace

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    I understand that you actually supercharge faster the lower your SOC when you arrive at the charger. The first leg of my trip will only be 80 miles, so I'm wondering if it really matters if I charge to 100% the night before or if 90% is better or won't really make a difference. I have a MS 70D.
     
  2. MikeC

    MikeC Active Member

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    No reason to charge to 100% at home unless you really want to save a few minutes at the Supercharger.
     
  3. wcalvin

    wcalvin Member

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    Depends on your comfort zone. Last night I charged to 100% (240 miles in 70D), drove 60 mles on I-5 on TACC and Autosteer, with no stop-and-go, but found the tank 100 miles down. And by then I didn't have time to stop at the nearby supercharger. So I was glad that I had max charged overnight.
     
  4. GasKilla

    GasKilla No Gas Know Peace

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    I was just reading the thread about how it's quicker to arrive at a lower SOC than a higher SOC on long trips, my trip only involves 2 superchargers so I'm not sure how everything applies to my situation
     
  5. chillaban

    chillaban Member

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    The advice to arrive at a lower SoC shouldn't be misinterpreted. Unless you value the time your car was charging the night before, those are essentially free miles.

    In my opinion, always start a trip with the max charge you have time to do. That will ALWAYS save you some charging time compared to hitting the road with a lower SoC.

    With that said, you are right that the battery charges faster at lower SoC. The right way to interpret that is, don't overcharge (buy too much margin) at a previous station if you can make it to the next one. For example, charging from 90% to 100% might take 30 minutes. Meanwhile charging from 10% to 20% only takes about 10 minutes. So, don't spend an extra half hour at your current Supercharger to charge to 100% just to arrive at 20% instead of 10% at the next station. That would waste 20 minutes in this example.
     
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  6. AEdennis

    AEdennis Active Member

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    It also depends on which supercharger...

    If you're stopping off at Fountain Valley or San Juan Capistrano or Burbank, if you can skip it, it's better. The wait times can be a bear and add a lot to your trip... if you're talking about Oxnard or Cucamonga or Barstow, you might be ok.
     
  7. MikeC

    MikeC Active Member

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    Yeah, charging speed tapers off at higher SOC. But 10% isn't a big difference and your first leg is short so you won't get to a low SOC anyway, so I think any difference would be mostly negligible in this case.
     
  8. chillaban

    chillaban Member

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    With superchargers, it's also important to remember that they tend to be 15-20x faster than your home charger, so in the end the answer might be "it doesn't matter". Charging 1hr at home might only be 5 minutes' worth of supercharging....
     
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  9. h-bomb

    h-bomb Member

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    I agree that in general, it probably doesn't make much difference in the long run. However, if charging to 100% allows for the possibility of _skipping_ the first supercharger, then yes, charge to 100% every time.
    I regularly take a trip that's 309 miles total; 2 superchargers along the route: 1st at 112 miles, next at 196 miles. I charge to 100% before starting, then by the time I'm nearing the 1st stop I can use the Wh/mi data thus far to see if I need to stop or not. Depending on weather conditions it's about 50/50. The times I can skip saves lots of time (not just charging, but exiting the interstate, parking, etc)
     
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  10. kort677

    kort677 Active Member

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    on a road trip it is almost always better to ride the bottom of the battery.
    I wouldn't even charge before leaving your house if the first planned stop is 80 miles away. how far away is the second SpC? it might be wiser to do a full charge and skip the first stop and make a run for the second stop arriving with a low SOC.
     
  11. bxr140

    bxr140 Member

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    As noted earlier, the 'charge to 100%' rule can be misinterpreted. The short answer is yes, you should always charge to 100% because yes, it will always make a positive difference in your total trip time. That 20+ miles extra will at some point equate to 20 less miles that you need to supercharge.

    Range charge won't harm your battery. Range charging takes a barely nonzero amount of your time to change settings (and back). There's absolutely no reason not to range charge in your situation.

    The soft side of the answer depends on what constitutes 'a difference' to you. The absolute fastest you can load ~20 miles at a supercharger is ~4 minutes, but for a 70 and the reality of not loading the bottom [fastest] 20 miles, you're really probably looking at a best case of 6-8 extra minutes of trip time, which of course can grow with things like being paired or if the charger is putting out reduced power, etc. And as noted upthread, if that extra 10% allows you to skip a charger you're going to realize a huge time savings--like probably 30 min or more.
     
  12. Ryan MF

    Ryan MF Member

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    Want to caveat that range charging one time won't hurt your battery, but every day will degrade the battery faster.
     
  13. GasKilla

    GasKilla No Gas Know Peace

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    It's 215 miles to the 2nd charger and will be with the wife & kid plus car full of luggage. Seems like a risk with my 70 D to skip the first charger
     
  14. chillaban

    chillaban Member

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    I personally would top off at the charger. But instead of spending 20 minutes there you might only have to spend 5 or 10 if you charge to 100% the night before.
     
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  15. Three60guy

    Three60guy Member

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    A wise owner once told me to charge for the unexpected. What if there was an accident on the freeway and you got caught in it. What if the temperature is low (winter). In other words, expect the unexpected. You will appreciate the extra charge when you come across traffic jams, bad weather, etc. I now do that and feel much better about it.
     
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  16. rfmurphy81

    rfmurphy81 Member

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    Have you plugged your trip into EVTripPlanner.com to see what that suggests?
     
  17. kort677

    kort677 Active Member

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    I agree in a 70 it is too big of a hop
     
  18. johnnyS

    johnnyS Member

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    On a road trip, always charge as much as you can when you are not waiting for it. So charge to 100% at home when you are sleeping, then you will spend less time at the first supercharger stop.
     
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  19. Three60guy

    Three60guy Member

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    I thought I would add one more item to think about.

    On our first trip to Western Iowa in our 70D our navigation said to stop by Lacross, WI for 5 minutes. Say what? My thinking was 5 minutes wasn't going to make any difference at all. What I was told by the wise owner of a Tesla is the navigation system takes into consideration not only distance but elevation as well. I, did in fact, not stop by that suggested 5 minute SuperCharger but learned a big lesson. Southern Minnesota is hilly. By the time I got to my next SuperCharger I had a charge of only 10%. Wow, no wonder it had asked me to charge, even if it was only for 5 minutes. And this was in the summer time. I doubt I would have made it during the winter time in my 70D. Lesson learned.
     
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  20. Saghost

    Saghost Active Member

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    I wouldn't want to leave it at 100% overnight - time at high SoC (or high temperatures) is what most degrades the pack.

    In the situation you described, I'd probably charge to 90% the night before, then set the limit to 100% as soon as I got up, and leave with whatever it got up to when I was ready to leave.
     
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