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Low SOC = Terrible Supercharging

Discussion in 'Model S: Battery & Charging' started by JohnnyLounge21, May 11, 2017.

  1. JohnnyLounge21

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    My apologies if this has been discussed, but I did a search and didn’t see anything on it. . .

    About a 18 months ago, I was in a 2014 Model S P85+ loaner while the Roadster was getting its annual. On a road trip, I ran the battery down to -2% rolling up to a Supercharger. When I plugged it in, she soaked up the charge like a desert sponge. Fast forward to last week. I did nearly the same thing (ran down to +3% SOC) on my own 2017 Model S 60 that’s a few months old. She barely took on any charge for 15+ minutes (yes, 15 mins). Same exact Supercharger, same 70 degree clear weather. I decided to move the car to another Supercharger (neither being shared in both cases). It still sat taking on very little charge for 5+ minutes so I panicked. I called Tesla and explained the situation to the letter. They told me that I’d need to be towed. Of course, I’m ready to go through the roof. As the call dragged on, the charging began to ramp up! As I’m conveying the improving state of affairs, the gal on the phone (with a technician in the background) began to say that this is actually expected b/c with such a low SOC, it would trickle charge “for a while” and then start ramping up. Well, it finally got into the 90+ amp range and after 90 mins total between both chargers, I was ready to go with exactly 200 miles (although I still could have taken on more).

    First: if this is the way of the world, how does such a simple question not go quickly answered given I had the facts ready to go for the attendant and presumably the technician? Why stress me with the possible tow?

    Second: this experience flies in the face of wanting to run the battery down further to get the strongest (quickest) charge to be most efficient on road trips <gospel that I took from the “How to save a lot of time on long trips” sticky thread>. Has something changed?

    Third: what of the 2014 P85+ loaner that took on a huge charge immediately in the exact same scenario? Did I dream that? I don’t think so b/c I remembered only being there exactly one hour and I had well north of 200 miles when we got back to the car. . .
     
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  2. Saghost

    Saghost Active Member

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    #2 Saghost, May 11, 2017
    Last edited: May 11, 2017
    We've seen some evidence that the newer silicon anode chemistry in the 75/90/100 packs has an issue or protection programmed in for very low states of charge, but there haven't been enough reports for us to completely understand it yet.

    Most of the prior reports were from cold places in the middle of this winter, which has led to some speculation that the pack temperature is a factor in the different behavior of the new packs.
     
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  3. AEdennis

    AEdennis Active Member

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    Which Supercharger? Perhaps there are issues going on at the location that Tesla was unaware of. Just a week and a half ago all three of the LAX area superchargers had the warning on reduced service on all of them (saw a tweet and confirmed in my own car).

    Here's my snark on Twitter - Dennis Pascual on Twitter
     
  4. mspohr

    mspohr Active Member

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    First: Not many people run their cars down that low and then Supercharge. Not good to do that.
    Second: Makes sense to get the battery up to a certain state of charge before Supercharging. Tesla is trying to protect the battery from clueless owners.
    Third: You're imagining it... or the algorithms have changed... or it was a different battery chemistry... etc.
     
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  5. apacheguy

    apacheguy S Sig #255

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    No, it would've happened at any supercharger. This issue primarily affects the newer battery chemistry packs as pointed out by @Saghost
     
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  6. Max*

    Max* Autopilot != Autonomous

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    I do it on every trip I take (well not negative, but between 3% and 7%)
     
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  7. JohnnyLounge21

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    "We've seen some evidence that the newer silicon anode chemistry in the 75/90/100 packs has an issue or protection performances in for very low states of charge, but there haven't been enough reports for us to completely understand it yet." - I think this may be one more report to the above point to build that case.

    This was at the Cabazon Supercharger (Palm Springs). When I was on the phone with Tesla as the charging continued to languish, they told me that the Supercharger was operating "normally" and hence gave me the tow appraisal. I didn't speak to the other 2-3 Tesla folks that were at the 12-bay Supercharger so I'm not sure if they had the same situation happening to them.

    I've owned a Roadster for 5 years and although I'm not an expert on the Model S, I'm very cognizant and respectful of battery health. I also researched the Model S for years before making the purchase. I didn't miss a single word of the 90-minute vehicle delivery seminar. In all cases, low SOC at a Supercharger being a danger to the car was never mentioned. I'll certainly try to not make a habit of that going-forward. But then - the "How to save a lot of time on long road trips" sticky thread claims and techniques go away (which I used as my guide to have an efficient road trip).

    My vote on what's changed is the battery chemistry as per what Saghost mentioned. New Model S owners should be aware of this and so should Tesla employees. This won't be the last time a new car arrives at a Supercharger with low SOC and panics and calls Tesla. There's a simpler answer than proposing a tow when the car needs to trickle for 20 mins.

    Lesson learned: when you arrive at -2% to 3% at a supercharger in a new Model S, be prepared to wait at least 90 mins if you want it charged all the way.
     
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  8. AEdennis

    AEdennis Active Member

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    I wonder if the Trip Planner algorithm changes based on which batteries one has in the car. If you followed Trip Planner, would it have plotted a more efficient trip? I tend to ignore it and just take its suggestions as "novelty".
     
  9. TexasEV

    TexasEV Well-Known Member

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    If you're respectful of battery health, why are you running the battery down to -2% or +3%?
     
  10. kingjamez

    kingjamez Member

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    New to Tesla's, but not to lithium batteries. I'm amazed that this is a "new" thing. In the 20 years that I've been using lithium ion cells, for at least 10 of them I've known that the right way to charge cells with a low SOC is VERY slow. C/10 or so. This prolongs battery life considerably and can save cells that are on the brink of self-destruction.

    In fact, 10 years ago, I had a special charger that I only used for specifically reviving very low SOC cells at very low charge rates.

    It seems like Tesla is rapidly implementing many battery management tweaks to enhance the lifespan of their batteries. Everything from launch mode limits, to the decreased charge rate after many DC fast charge sessions, to this... all things that will very positively enhance the battery life spans.

    Frankly, I don't know why it's taken them this long to implement these "features", they've been well known for a long time.

    -Jim
     
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  11. Saghost

    Saghost Active Member

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    What's interesting is that all of these new features appear to only be applied to the new chemistry cars - according to the DCFC limit thread, even today 85s and original 60s aren't affected, with many more miles and sessions. I've never seen a report like the one that started this thread before this year, but there have been several this past winter - all new chemistry cars.
     
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  12. Naonak

    Naonak Member

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    Tesla needs to change their "you have enough energy to continue your trip" calculations drastically then. I always arrive at the next SC low on charge. In fact, if I ever left when the message popped up, I'd be stranded. I always put a buffer in and still arrive low SoC. It's not clueless owners, it's clueless engineers.

    God forbid an owner doing what the car says to do and then wondering why they are stranded. Or throttled.

    It may positively enhance the life spans, but it is slowly sucking the life out of the car. If Teslas strategy is to sell one car that can do certain things, but then later nerf the car so it can't do any of those things to "protect it," then there's a major problem and disconnect somewhere. Either sell the car like it will function for most of it's useful life, or suffer the warranty consequences for selling a car that can't perform as advertised without breaking down. That's really the only two morally acceptable choices.
     
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  13. stopcrazypp

    stopcrazypp Well-Known Member

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    The numbers quoted in this case however seems a lot lower. OP says 90+amps was not reached for a while. That's slower than CHAdeMO.
     
  14. cgiGuy

    cgiGuy Active Member

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    Not sure it's just for new chem.. I can recall this happening once in my 2013 MS 60. Was driving from South Carolina to Texas and limped into a charger in Baton Rouge or Lake Charles at 0 miles of range remaining. Took 10 mins or so before it would ramp up.
     
  15. Saghost

    Saghost Active Member

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    I wasn't referring to the DCFC limit thread from this week, but to the reports from the winter of the car seeming not to take a charge at all for 20-30 minutes after arriving with single digit miles, then rapidly ramping up to normal Supercharger rates.

    Low Battery Supercharging - 0 Kw and 90 minute charge time

    Sat for 40 min at 0kw supercharging
     
  16. hiroshiy

    hiroshiy Supporting Member

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    Haven't experienced this yet personally, but what is the lowest SOC to prevent this slow ramp charging from happening?
     
  17. Saghost

    Saghost Active Member

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    Lots of things we don't know. I'm pretty sure 7% is safe based on my personal experience, not sure how much below that is.
     
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  18. Chris TX

    Chris TX Active Member

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    I've taken my S85 below "0 Miles" once or twice, rolling into a Supercharger. Immediately, the charge rate starts out ~5kW for maybe 5-10 minutes. This gets the battery up to a safer low SoC level so it can turn on the full ~120kW charging. Once it gets to 1-2 miles of range on the battery, I've seen the rate jump back up. I haven't had my OBD2 cable connected to capture what it's actually doing, though.
     
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  19. mspohr

    mspohr Active Member

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  20. Saghost

    Saghost Active Member

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    That's what we assumed was happening in the winter, although it seemed odd that these batteries could be that cold after a long drive. But this thread's OP sounds exactly like the two I cited to me - except without the possibility of a cold pack.
     
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