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Fast charging

Discussion in 'Technical' started by dpeilow, Jan 29, 2009.

  1. dpeilow

    dpeilow Moderator

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    #1 dpeilow, Jan 29, 2009
    Last edited by a moderator: Jan 29, 2009
    I was recently talking to some people who are planning to install two 2MW wind turbines. The said that they will have to bring in a HV grid connection over about 5 miles and that they were on the threshold between needing 11kV and 33kV lines. They were quoted £1.5m by the local power company.

    Now a commercial 10 minute charging station would most likely be ok with 11kV and I doubt it would be 5 miles from the grid, so finger in the air it is likely to be half that amount. (Anyone have any other quotes we could use to pin this down?)

    It's not ridiculous number to establish such a station once the EV market grows and it is a lot less than figures I have seen for commercial size hydrogen stations.


    None of which takes away from the SSC 220V domestic socket claims being total bull...
     
  2. donauker

    donauker Member

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    #2 donauker, Jan 29, 2009
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    I certainly agree that the claims put out by SSC which started out as total insanity have merely made it down to the level of total BS.

    But I do believe there is some misconception on this forum as to the level of electrical power that is readily available in commercial and industrial areas. I am familiar with the electrical service at two local grocery stores in my rather rural area. The larger of the two would be considered a large store but certainly not a super store, it's service has a 1.5 MW capacity. The smaller store has a 1 MW capacity. There is nothing unusual or special about these stores.

    Also construction costs for gasoline service stations regularly runs several million dollars. The costs for underground tanks and all the required safety features is significant. In past years the cost to comply with updated regulations have driven many stations out of business.

    I believe the only thing needed to bring fast charge stations into existence is for enough people to be willing to pay the required higher price for the same electricity that they can get at home for much less. Personally I see almost no times I would need anything faster then a 45 min. charge next to a decent restaurant or a overnight charge at a hotel for all of my away from home travel needs.
     
  3. Tdave

    Tdave Member

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    A turnpike service stop that could accomodate 200 Tesla EVs charging while the owners eat lunch would require 14 MW of service with each car at 70 kW.
     
  4. Tdave

    Tdave Member

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    If EVs were widely used, could you imagine the MASSIVE draw on our electric grid during lunchtime on the day before Thanksgiving?
     
  5. donauker

    donauker Member

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    And wouldn't that be a glorious sight to behold! It is hard to imagine how many electric cars would need to be on our roads to have 200 requiring a quick charge in a single location at a single moment in time. I look forward to that day.

    I believe the our electric companies would be thrilled with the opportunity to sell 14 MW of power at or above small customer retail rates. It seems a much better return then providing 40 to 50 MW of power at wholesale rates for your typical electric arc smelter furnace.
     
  6. SByer

    SByer '08 #383

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    Might that draw be offset by so many businesses being closed? Curious thought.
     
  7. stopcrazypp

    stopcrazypp Well-Known Member

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    #7 stopcrazypp, Jan 29, 2009
    Last edited: Jan 29, 2009
    That really would be a sight to behold.

    Though if 1MW service is avaliable readily then it's not too much of a stretch to open a station with 4 car capacity (each using 250kW of power) to provide ~10 minute charging (35kWh pack, ~150 miles of range, don't need a very big pack if rapid charging is available). A 2MW service can power a 8 car station. If you have some slower chargers rather than all rapid chargers then you can charge more cars at the same time.
     
  8. Tdave

    Tdave Member

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    OK, let's not start talking about 10 minute charges again. According to Tesla, maximum charging speed is 45 minutes with current chemistry.
     
  9. Palpatine

    Palpatine Banned

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    #9 Palpatine, Jan 29, 2009
    Last edited: Jan 29, 2009
    I agree. And frankly I don't think 10 minute recharges are even necessary.
    When I make a long car trip, I need to stop for a break every 3 hours. Restroom, bite to eat, etc. I think that even people on a road trip would be fine with that standard.

    Just to use a Tesla Roadster example, at 65 mph it will do about 200 miles, even on standard mode (90% SOC to 10%). That is about 3 hours of driving.

    I have driven across the USA from Florida to Seattle Washington. It is really tough to do more than 700 miles per day when you have kids in the car.

    If I had a Tesla Sedan with a 300 mile range, I am positive that during a 700 to 800 mile day that we would be making two stops of about an hour each time. If fast recharging was available (440 volts, 160 amps) then that would likely be sufficient to meet the long range needs of most EVs.

    The business model of gas stations is not just to sell you gasoline/diesel. They need you to come inside, buy some snacks, drinks, eat, etc. The financial incentive, in an EV world, would be to install a fast charger, but not too fast. They would love to have a captive audience for about 45 minutes to an hour.
     
  10. TEG

    TEG TMC Moderator

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    To be clear - that is how they see it based on the chemistry they are currently using. Other types of batteries could conceivable allow 10 minute recharge assuming you have access to the required current levels and charging equipment.
     
  11. vfx

    vfx Well-Known Member

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    Dave,

    You did click on a thread entitled "Fast charging"...
     
  12. Tdave

    Tdave Member

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    Good point. I would like to point out however that these posts were moved here by the mods from the thread on the Ultimate Aero where we successfully came to the conclusion that the 10 minute recharge claim was complete bunk ... (anytime soon).
     
  13. doug

    doug Administrator / Head Moderator

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    Right, I moved a few posts so we could have a thread about the technical issues involved with fast charging in general (and not just about that SSC). We can have a separate thread about the Tesla 45 minute charge, if you wish. But discussion about the 10 minute charge (a totally different ballgame) is fair game here. It should be noted that prognosticators such as Siry have gone on record to say that fast chargers (the 5 minute or so kind) are needed for electric cars to be accepted by the general public.
     
  14. Tdave

    Tdave Member

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    I read that. Makes sense and may turn out to be true. I'd like to think, however, that it would be possible for a sea change (maybe slowly) of acceptance as more and more adopters realize overnight charging for day to day use is perfectly acceptable, and 45 minute charging on the road for trips works fine too.

    I think the change that will make the charge time moot will be better energy density per volume and weight, as Elon just alluded to with the advancements for the Daimler pack, that will allow much better range. If in 5 years I'm able to replace the battery of my Roadster with a battery that has 500 miles of range, then even long day trips become no problem. If I'm able to add 100-200 miles of range charging during lunch at the turnpike service stop, all the better.

    Therefore I believe the fast charge problem will become mostly moot if these two things happen first.
    1) Long range EVs of 500 miles per charge.
    2) Widespread infrastructure of overnight charging at hotels and friends homes (220V 70A to charge that 100 kWh battery in 7 hours).

    With that 500 mile pack, if I can plug in almost anywhere I park for the night, and also at a good selection of restaurants, then I have no worries ... ever!
     
  15. vfx

    vfx Well-Known Member

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    Re sea change,

    I know I'm bias since I want a real EV but if you get in a room full of EV owners and they all start talking about charging and how it's just a shift in how you think and that it's really no trouble plugging in, that it's no problem at all dealing with mileage limitations, it is easy to get swept up in believing that it may not be all that bad.

    Like being in a room full of people that all loudly swear that a movie is good when you heard it was bad. At the end you say OK, maybe I'll try it.

    That's the way the it will will happen. The naysayers will not have the experience of having driven an EV so their complaints of difficulty will ring hollow next to early adopters saying it's no big deal.

    Call it peer pressure, group dynamics, whatever, we are riding the wave of the sea change.
     
  16. TEG

    TEG TMC Moderator

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    Maybe someday in the distant future, but for now, slower chargers in more places seems like a better approach.

    Yes a quick charge is convenient, but there are a lot of reasons not to count on them:


    1. High current is not available everywhere. (Want/need industrial 3 phase nearby)
    2. More potential danger to those hooking up if there is an insulation breach.
    3. Bulkier/heavier/thicker cables to move around.
    4. Much more expensive equipment.
    5. Quite possibly less efficient than slower charging.
    6. Heat build up that needs to be dealt with.
    7. Many battery chemistries and architectures that don't support it.
     
  17. Palpatine

    Palpatine Banned

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    It might look something like this...

    Parking lot of the future? Peak Oil Garage
     

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  18. shark2k

    shark2k Member

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    #18 shark2k, Jan 29, 2009
    Last edited: Jan 29, 2009
    Addressing the points 5 and 6. I was actually gonna bring that up based on another thread that had mentioned the fast charging. I think it was talking about charging at home with the HPC. I believe TEG (could have been someone else) said that in order to charge in 3.5 hours it requires more power because the battery pack needs to be kept cool. If you can get the same full charge in 8-12 hours (charging over night) and not need to use the 3.5 hour capability, wouldn't you end up using less energy?

    Also, can't you "program" (not sure if that is the word I want) the Roadster to charge at a certain rate? I vaguely remember reading that on one of the threads on this site. So I was under the impression that (it might even be based on a setting) you could plug the Roadster in and have it so that it finishes right before you need. With that if you plugged it in at 5 PM (get home from work) and you need it at 7 AM you have 14 hours to charge it, so it can charge at a slower rate. But if you got home at 9 PM one night and still needed it for 7 AM you now only have 10 hours to charge it so a quicker rate would be used.

    I guess what I'm kind of getting at (besides trying to get some clarification) is wouldn't it be better to use fast charging (even the 3.5 hour charge) as little as possible?

    -Shark2k
     
  19. TEG

    TEG TMC Moderator

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    I think it is rather complicated. Try reading these:

    Battery Chargers and Charging Methods


    Battery Performance Characteristics - How to specify and test a battery
     
  20. doug

    doug Administrator / Head Moderator

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    Tesla Dave, I pretty much agree with everything you said and basically disagree with what Darryl had to say. In all fairness to Siry, he was discussing fast (5 minutes or so) charging coupled with relatively low battery capacity as a lower cost bridge to when larger capacity batteries become more affordable. But given that you'd need at least a 40 mile range for the car to be acceptable; the infrastructure needed, technical challenges, and cost of setting up the prerequisite fast charging stations; the fact that the batteries that can support that kind of charge rate tend to me more expensive; and that PHEVs appear to be the technology that will fill that bridge role (gas stations aren't going away anytime soon), I think he pretty much missed the boat on that one.

    (This post employed gratuitous use of the semicolon.)
     

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