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Ludicrous charging?

Discussion in 'Model S: Battery & Charging' started by Dbitter1, Oct 2, 2015.

  1. Dbitter1

    Dbitter1 Journeyman Member

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    So... discounting the minor details, and adding all the fine print about various battery states, and such...

    We now know that our older MSs can put at least 1200 A of current through the battery leads... and that the shiny new ludicrous ones could take 1500A.

    If, hypothetically, some REALLY large transformers fell off a truck somewhere near a sub-station with a high-tension power line drop and a group of ninjas wired it up, along with any needed changes to the SC protocol handshake and maybe a liquid nitrogen bath for the cabling to support same... is there a reason that we couldn't use charge at max capacity? I mean 400Vx1500A = 600KW charge rate... damn, we could fill our cars faster than an ICE...
     
  2. David99

    David99 Active Member

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    As far as I know, the way Lithium batteries are designed, they can always be discharged at a higher rate than charged. So max discharge rate isn't automatically charge rate.
    The other big difference is that the peak power draw might be 1500 Amp, but it's only for a few seconds. The battery is not capable of sustaining that rate. There is no way the battery would be able to take a charge rate that high. I think even a perfect cooling system wouldn't be able to work. There is so much heat generated inside the cells but it can only be cooled from the outside. The cell would end up getting too hot at the core and the areas near the edge would be too cold. Such a temperature difference within the cell would be pretty bad for it.

    I think it will be several years before we see a significantly higher charge rate. The battery, it's cooling system and the Superchargers would have to be upgraded. Right now they are all designed to max out at 150 kW or something like that.
     
  3. Candleflame

    Candleflame Member

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    The way to improve the charging experience is to a) increase battery capacity and b) improve tapering. A charge rate of 135kw is already super quick. Would charge a Model S85 from 0 to 90% in about 33 minutes (Assuming 9kwh reserve/brick protection). Unfortunatley the charging tapers off rather quickly.
     
  4. AmpedRealtor

    AmpedRealtor Active Member

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    With the right battery, you can also double the voltage as in Porsche's new E concept to halve the charge time.
     
  5. Dbitter1

    Dbitter1 Journeyman Member

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    Sure... I suppose the high end is dreaming, but what *IS* the actual limit based on? What kind of look do you think you'd get if you told some dinosaur evaporator gear heads 10 years ago that in 2015 there would be a sub-$200 production model car that can do 2.8s 0-60 with zero emissions?

    Sustain for what? I can likely run all 1500A through a 26AWG wire if I cool it adequately. And there are like 7K cells, right? So it is a fraction of an amp for a few minutes (lol, still dreaming, play along) if we can get the cooling right.

    Ok, here I have to agree. There would be a hell of a temperature differential and that is usually very bad. So we'd need to say, then, that the fundamental design would need to change to something a little more proprietary for the really bulky loads... if only, say, there was a massive factory that could make all the cells Tesla could feasibly need being built somewhere...?

    I suppose that it is still dreaming, yes, but so is a big-ass maglev train in the middle of California and it looks like that might happen...
     
  6. AWDtsla

    AWDtsla Active Member

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    The problem is energy over time. 1500A discharge can only be sustained for seconds because you've maxed out the velocity of the car. Charging is continuous load for a long time.
     
  7. gregincal

    gregincal Active Member

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    OK, but at this point you've ignored so many problems that why even use the current battery lead limitation. Who's to say we won't be able to charge at 1.21 gigawatts? I've seen it done, you just need a portable nuclear reactor (or a lightning strike).
     
  8. ddimit

    ddimit Member

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  9. Dbitter1

    Dbitter1 Journeyman Member

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    Ok, I'll bite...

    Lets start with the disclaimer that while I know a respectable amount about a lot of things in science, I'm not a chemist. I know that LION batteries are pretty durable, have a respectable power output for their weight when compared to pretty much anything, and a much lower environmental impact than most other energy storage types. I'm also aware that there are temperature restrictions to the reversible chemistry of the little Lithium ions floating between their plates; outside of a prescribed range of roughly 32-100F bad things happen when you charge rapidly. That's about it.

    That's the chemistry that I don't think we can easily change right now... if I knew how to make a better battery... uh... lets say my "location" tag would say "private Caribbean island with nuclear weapons".

    But... those "other" factors are all things that can be fixed with today's technology for the right price. I know (thanks WK057 et al) that there are some coolant channels in the battery today, but don't know the cooling capacity of them.


    Power company drop... easy, for the right place. Maybe someone's uncle wants a SC at their nuclear power plant, and has a excess 3GW capacity due to the propensity for fracking now-a-days on the open market. Real example: Here in Chicago we had a steel mill close in one of the industrial districts... it was the single largest consumer of power in the city when ingots were heating... now, demolished and waiting for someone to build condos on it. But the infrastructure remains, I'm sure ComEd (our power co) would be thrilled if someone wanted to pay them for a OMFG ludicrous 3ph power drop.

    We know the SC bay uses an array of chargers, so we could theorize that a bigger array = more DC output.

    For charging cables, there are a billion ways to keep them cool, a finite, non-zero number being practical. Remember your gas station days? Those hoses sucked air/fumes while they delivered that icky dinosaur juice; what if we ran coolant through them in one direction and electrons in the other?

    Saying "yeah, coolant is the limiting factor cuz the cable from the charge port to the power pack isn't in a coolant bath" is a fine way of conclusively answering the question... just have not torn down my car to be able to say that myself. I can cool the parts after that (outside the car).

    Maybe (and I'm stretching here) a pulsed DC would have a better net effect (doesn't AC call that "RMS" voltage) on power as it relates to battery chemistry that would be harmful continuously?

    And lets say it is a battery limit... ok, we know the P90DLs have a "beat up my battery, I know it is not covered under warranty, but I need them HP's right now so just do it" switch... what if I wanted to catch my dying relative's last words and didn't care if my battery went from a 8 yr useful life to 7 yrs, 11 mos, 3 weeks, and 6 days if I got to hear them because I only needed 5 min at the supercharger rather than 20?

    Consider it a thought question...
    :wink:
     

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