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Superchargers might max out at 200kW

Discussion in 'Supercharging & Charging Infrastructure' started by Cosmacelf, May 2, 2018.

  1. Cosmacelf

    Cosmacelf Well-Known Member

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    In today’s May 2nd conference call, Elon said that they were still working on V3 of the Supercharger (but it didn’t sound imminent), but that it would probably max out at 200 kW. He didn’t think they could make a battery that could accept more than 200 kW.
     
  2. Tam

    Tam Well-Known Member

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    It sounds like Tesla doesn't think Porsche’s 350 kW charger is beneficial for today's battery packs because none are large enough to take that.

    There doesn't seem to be any commitment for any increase in Supercharger rate but Tesla does discuss and explore on the subject.

    That sounds like you need to convince Tesla there's a good trade-off in order for it to consider an increase in Supercharger rate.

    In the past Tesla has ruled out on any commitment beyond 100 kWh capacity for Model S/X battery packs. So that's a good hint that Supercharger rate won't be improved any time soon.

    On the Semi side, Tesla hasn't finalized on Megachargers pending on talks with their customers.

    That is not Apple's way because planning a future product with customers would eliminate the surprise element!
     
  3. J1mbo

    J1mbo Active Member

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    Basically means they have no plans to move to an 800v architecture any time soon.
     
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  4. Mobius484

    Mobius484 Supporting Member

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    I agree, But if we started seeing more consistent >100kw charging and more solar/power pack rollout, l’d more than happy...I wonder if as the chemistry improves in the fleetwide packs, they will increase the limits for older batteries, and eventually when they do come out with batteries that can accept that charge rate safely, will they offer battery replacement at a fee? The current stuff slightly faster with more locations would be good enough, for the next few years in my opinion...
     
  5. HoptownT

    HoptownT Member

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    So I guess charge time isn't changing significantly until batteries move to solid state?
    What is a solid-state battery? The benefits explained | WIRED UK

    I keep waiting for the casual announcement that charge times are 8 min starting on new models as of X date on twitter to smack down Porsche before Porsche hits the road. They can't one-up us but maybe they will...
     
  6. mongo

    mongo Well-Known Member

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    My take away was that they could, but it would not fit the vehicle use case.

    From the Seeking Alpha transcript:
     
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  7. David99

    David99 Active Member

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    Going with a higher voltage is the only way to reasonably increase the Supercharge rate significantly. 200 kW at the same voltage would require cables so thick that they would not be practical any more. I think the charge plug would also need to be redesigned to handle 600 Amp. If you double the pack voltage you can double to charge rate with the exact same cables and plugs. Electric losses increase geometrically with the amps but not with volt. That's why power lines operate at such high voltages. They minimize the losses.

    But that's all next generation. I think there are a few things Tesla could do right away. They could do away with the stall pairing and have each plug with a dedicated charger. As Superchargers get busier the sharing thing reduces charge speeds unnecessarily. They could also optimize the cooling during Supercharging.
     
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  8. Cosmacelf

    Cosmacelf Well-Known Member

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    Even if you had an 800v battery pack, you still have the problem of charging at a really high C rate. As Elon says, you’re going to frag the battery pack. Elon and JB are saying that they haven’t found a way to get high C rates from a high energy density battery. So that means you would have to have a larger battery to get the C rate into acceptable territory. And Tesla, apart from the semi with their mega chargers, is saying that they don’t want or need big battery packs. A 300 mile range is where they think they need to be, and have no reason to go beyond that, except for a more expensive specialty car like the Roadster 2. And even in the Roadster 2 case, there is no need for faster charging since you charge about twice less often than with a long range Model S.

    So, really, 200kW is it, at most, for Tesla.

    Given this logic, I suspect the Porsche 350kW charger is simply a marketing gimmick with no useful application. Which fits perfectly in with legacy automakers way of doing things.
     
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  9. mongo

    mongo Well-Known Member

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    @Cosmacelf covered a lot while I was typing...

    High voltage helps in delivery of higher power for the reasons you mentioned. However, the pack voltage doesn't impact the charge rate it can handle which is based on capacity / kWh.

    Liquid cooled cables, like high power CCS, would work with closer mounted chargers, otherwise the site setup will require running liquid cooled lines all the way from the cabinets. The CCS plug is speced to 400-500A in liquid cooled mode (125A normal).

    Based on that derating factor, a 400V liquid cooled SC could do 400kW, but the pack would need to handle that rate (4C for a 100, 2C for a Roadster 2020). 200kW might be more likely.
     
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  10. David99

    David99 Active Member

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    Porsche's 350 kW is most likely a theoretical maximum. But let's wait and see what they come up with.
    As far as I know the cables in the ground at Superchargers are maxed out at 350 Amp. Tesla can't upgrade the Superchargers to 200 kW unless they dig up the ground. That's why I'm thinking, to get a significantly higher charge rate, they have to go higher with the voltage. But yes of course the batteries have to be able to take the rate. That's unlikely in the near future unless there is a breakthrough in battery chemistry.
    But then, battery technology and production is going to be incredibly important and humongous in the near future as EVs take over the car market. Everyone knows that. Whoever has the edge can grab the majority of the market which is going to be huge. There are several big companies putting serious money into battery R&D. Tesla isn't the only one. Maybe someone other than Tesla will have a better battery in a few years.
     
  11. quantumslip

    quantumslip Member

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    Does anyone know if the current connectors (Type 2 and Tesla NA) could support 800V? Or would it require a redesign/change to do so? Do the connectors need to be placed further apart or is that not an issue? This is apart from the packs/infrastructure being upgraded to support 800V
     
  12. mongo

    mongo Well-Known Member

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    CCS type 1(US) DC is 600V, type 2 is 1000V per Phoenix Contact (not sure if that is 1.0 or 2.0)

    For others with 350kWh, how are they interfacing to the grid? That is the equivalent of 7 houses with 200 Amp service going 100%...gonna need some storage to buffer...
     
  13. miimura

    miimura Active Member

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    IIRC, Continental, the automotive supplier, has shown a DCFC charging box that can be integrated into a vehicle between a 800-1000V charging inlet and a ~400VDC battery pack. That would reduce the size and cooling requirements of the charging station cabling and connectors and still allow the more traditional pack voltage and drive inverter design. However, it doesn't do anything to address the C-Rate of charging a vehicle's pack at over 150kW.
     
  14. mongo

    mongo Well-Known Member

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    Huh, so the car basically has an AC charger and a DC charger... technically, the AC charger could be built to handle DC also, but that whole approach seems like it defeats the purpose of DC fast charging..
     
  15. TaoJones

    TaoJones Beyond Driven

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    Today, the Tesla Semi uses existing SCs with some sort of special (dual cable?) adapter. I wonder how that works. I realize that dedicated SCs for Semis will probably be the rule (much like cardpass-access fueling depots for truckers today) since time is money. And since those SCs would ostensibly be for Semis only, I guess they could size/scale the equipment any way they want. Hmmmmmmm.
     
  16. miimura

    miimura Active Member

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    Not really. It allows you to transfer high power with smaller cables all the way from the DCFC cabinet all the way into the car. The DC charging box is just a step-down DC-DC converter.

    From what I've seen, the Semi has 4 separate battery packs, so it could be charged with up to 4 Supercharger cabinets. People have seen the 4 -> 1 Supercharger -> Megacharger port adapter cable in the wild.
     
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  17. mongo

    mongo Well-Known Member

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    The current AC charger is (likely) an AC to HV DC power factor correction stage followed by a DC-DC stage for current control. Hummm, really it may be able to do a higher input voltage natively...

    My concern is that even a 95% efficient DC-DC converter at 250kW needs to dissipate 12kW (40kBTU). Current internal charger max rate is 80kW I think, so 3x that with 40% efficiency gain is still 1.8x heat load.
     
  18. miimura

    miimura Active Member

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    Any charging system that operates at over 150kW will require significant and strategic cooling. One could argue that Tesla cars should have actively cooled charge ports. I would expect to see some new thermal management techniques in these higher power systems in new cars. For example, BMW does not use liquid cooling in the i3 battery pack, it uses direct refrigerant cooling. A concentrated heat source like a 250kW DC-DC converter would benefit from that kind of cooling system as well.
     
  19. mongo

    mongo Well-Known Member

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    All valid points. My philosophy being the less heat on the car side the better/easier/cheaper. I'm also a fan of less stages of conversion. If the superSC connector cools the pins, then the limiting factor will be the contactors and pack heating (vehicle cables from port to pack can be sized to match max charge current).
     
  20. Iwantmy3

    Iwantmy3 Member

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    The maximum charge rate for the model 3LR decreases as the battery is charged. From what I have seen, it appears that the car can accept 200KW x %uncharged. On a 110KW supercharger it can take the full load until it hits ~45% charge. The maximum it takes then decreases linearly as the % uncharged decreases.

    With this in mind, the benefit of a higher maximum charge rate is minimal. It could save 5 minutes on a charge (at best)

    Until there is a breakthrough in battery technology, I would prefer many more of the current superchargers rather than a few more of the 200-350 KW style (which I would assume to cost exponentially more per station)
     
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