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Why more superchargers alone can't prevent overcrowding

Discussion in 'Charging Standards and Infrastructure' started by Teo, Jun 24, 2014.

  1. Teo

    Teo Banned

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    #1 Teo, Jun 24, 2014
    Last edited: Jun 25, 2014
    Every time when there is a discussion about the future of superchargers and how they will cope with increasing number of Teslas, a few people jump in and say more stations will be built and it will be just fine. But when you think about the details that doesn't make sense. There is no way adding more stations can prevent extreme wait times. I'll explain why.

    In 2013, 18.195 Model S were sold in the US. In first 5 months of 2014, 6800 have been sold (source) which gives a year-end expected sales number of 6800/5*12= 16.320. Let's be modest and assume Model S sales will be 16.000 per year for the following few years; Model X will sell 16.000 units from 2015 on and Gen 3 will sell only 50.000 units in 2018 and later.

    Using these numbers, sales in the US would be like this for each year:

    2012: 02.558 (Model S)
    2013: 18.195 (Model S)
    2014: 16.320 (Model S)
    2015: 32.000 (16.000 Model S + 16.000 Model X)
    2016: 32.000 (16.000 Model S + 16.000 Model X)
    2017: 32.000 (16.000 Model S + 16.000 Model X)
    2018: 82.000 (16.000 Model S + 16.000 Model X + 50.000 Gen3)
    2019: 82.000 (16.000 Model S + 16.000 Model X + 50.000 Gen3)

    Total number of Teslas in the US would be as follows at the end of each year:

    2012: 002.558
    2013: 020.753 (2.558+18.195)
    2014: 037.073 (2.558+18.195+16.320)
    2015: 069.073 (2.558+18.195+16.320+32.000)
    2016: 101.073 (2.558+18.195+16.320+32.000+32.000)
    2017: 133.073 (2.558+18.195+16.320+32.000+32.000+32.000)
    2018: 215.073 (2.558+18.195+16.320+32.000+32.000+32.000+82.000)
    2019: 297.073 (2.558+18.195+16.320+32.000+32.000+32.000+82.000+82.000)

    As you can see, at the end of 2019, number of Teslas in the US will be more than 10 times of what it is now. Currently there are 27.553 Model S in the US (2.558+18.195+6.800=27.553). I can hear the same people saying, "Superchargers will be 10 times more too." OK, let's assume they will be.

    Number of stalls per station is limited by two factors: available parking space and capacity of electrical infrastructure. In the UK Tesla and Ecotricity are already fighting each other for the same rest stop locations because in some locations Ecotricity can't even add more of their own stations because power capacity is limited. They don't want Tesla to come in and kick them out. Of course parking space is limited too. Because of these two limits number of stalls per station can't go over 10 stalls on average. Currently there are only two locations with 10 stalls. Most locations have 8 or less. At http://supercharge.info you can click on 'Data' and sort by stalls.

    Certainly it would be nice if Tesla could expand an existing station from 10 stalls to 100 or 50 or 20 but that's not going to happen for almost any existing station. Therefore Tesla needs to increase number of stations. Some might say, "That's not a problem. They will just spread them equally every 20 to 40 miles along the highways like gas stations." But can they?

    The distance between Los Angeles and Las Vegas is a fixed number that doesn't change. The range of the cars is more or less the same. Variables like elevation and weather will have the same effect on all cars driving in the same direction on the same day between the same two cities. When you leave a city you typically don't need to charge too soon because you will leave with a charged battery. Even if you wanted to charge soon after leaving a city it wouldn't make sense because charging a battery that is somewhat full takes more time and charging too early won't give you enough range to get you to your destination.

    What is going to happen is, in 2020 there will be up to 10 stations between LA and Vegas on a 100 mile stretch in the middle. "So what's the problem?" some might say. "The probability of drivers picking one station or another is the same, isn't it?" Even if there is some randomness, does this mean some stations could be packed while others are half empty? We don't see this happening with gas stations (except maybe when they have a discount price).

    But I think gas stations and supercharge stations are very different for two reasons: Firstly if you arrive at a gas station that has 10 pumps and there are 20 cars, it is not a big problem. You will only wait maybe 5 minutes. If the same were to happen at a supercharger you would wait 45 minutes before you start charging. Secondly, if for some reason gas station is too crowded (maybe because of discount price or some pumps not working or some special event in the area), an ICE driver could just drive to the next station. At a supercharger this is not easy because you have already driven away from the main highway, you might not have enough range and even if you have it is not guaranteed the next supercharge station won't be even more crowded.

    Here is another way to visualize the problem. Imagine there is a group of 15 people on the street. There are a bunch of restaurants in front of them. The reason I like the restaurant example is because the time you spend there is comparable to a supercharge time. Therefore comparing superchargers to restaurants makes more sense than comparing them to gas stations.

    Each restaurants has 10 chairs and they are all empty. The diners can pick any restaurant they want but once they are in, they can't switch. Because number of people is not too high compared to the capacity of each restaurant, statistically it is unlikely that more than 10 people will go to the same restaurant. It might happen but it will be uncommon. And when it rarely happens there will be 11 or maybe 12 people and the wait time won't be too long for most of the diners.

    Now let's multiply number of diners by 10. Now we have 150 diners on the street waiting to go to a restaurant but each restaurant can only have 10 diners (because as you remember we couldn't increase number of stalls). Even though now there are lots of restaurants, because the number of diners is so high, it is now very likely that some restaurants will have 20, 30 or maybe more guests while others have none or few.

    As you see increasing number of stations doesn't work even if you increase them at the same rate as number of cars. If Tesla was building superchargers on their own land with enough empty space to add lots more stalls over time then this problem wouldn't happen.

    Update: Here is another analogy:
    Imagine an office worked sitting on a desk and processing documents. She can process 10 documents in 40 minutes, representing a station with 10 stalls. There is a steady stream of 10 customers per 40 minutes. Demand and capacity is an exact match. Customers put the documents on the desk and leave.

    Now let's double the demand from 10 customers to 20 per 40 minutes. We need to double the capacity too but unfortunately we can't make the office worker process more documents (replicating 10 stall limit). Instead we add another desks and office worker.

    When people arrive they have to leave their documents on one of the desks without knowing the workload. This replicates the fact that you don't know how crowded a station is before you arrive there. Because the randomness of choice sometimes one desk or the other will be overloaded.

    Now image demand would increase 10 times instead 2 and there would be 10 desks. The possibility that some of desks will be overloaded a few times their capacity is high.

    Around 2019, 30 Teslas waiting to charge at a 10 stall station is likely to happen if things were left alone. But given that there are so many smart people at Tesla, they must be thinking about these things already. Here are some possible solutions that Tesla might use, although each have a downside.

    1. Smart Navigation: In one of the meetings, could be Amsterdam or Oslo, Elon said in the future you will never have to worry about superchargers. He said you will enter your destination and the navigation will pick the supercharger for you. To me this means a central computer will monitor empty stalls in all superchargers. It will then make a calculation based on your current location, distance to different stations, your speed, your remaining range. Then it will assign each car to a different station.

    I think this should work fine but if all Teslas don't have a 3G connection in the future, it can't work. Also it can't work if superchargers are shared with another car maker.

    Update: dsm363 said with the Gen3 Tesla might offer free 3G for life that comes without web functions. I think that sounds like a great idea.

    2. Digital road signs: Because you have to divert from the highway to go to a supercharger, you don't want to go there just to find out it is extremely crowded. So if there were digital road signs on the highway that show available space for upcoming stations like "Tesla supercharging 1 mile, available stalls 3", then you could decide whether to skip or take it.

    One problem with this is, if the distance from the sign to the station is too long, it could be full by the time you arrive there. Because if it shows 1 available space and somebody takes the turn from the highway, until that car arrives at the station the sign will continue displaying 1. But during that time other cars might also decide to go there. The further away from the highway, the worse the stations will be.

    Update: Zextraterrestrial said the information would be on the screen in the car instead on road signs. I think it is possible. This would be an earlier version of the smart navigation. I think before there is smart navigation it is more like to have real time availability data on the screen. So I think I was wrong with the road signs idea. On screen data is more likely. So here the new version of #2:

    2. Real-time availability data: On the 17" screen you will be able to see how many stalls are available in each station.

    3. On-road stations: What would be great are charging stations on pit stop lanes parallel to the main road. Of course at highway speeds you can't look and decide whether you want to stop there. So digital road signs still need be placed before these stations. But because the stations are so close to the signs, there is no risk of arriving there and finding the space occupied.

    The problem with these is, they are not great places to spend time. You are stuck in your car and there are no facilities around. It is also a bit of a security risk and you still need to stop at a restaurant and restroom.

    4. Mega Stations: At critical locations such as LA to Vegas where a single station in the middle would be sufficient, Tesla could build mega stations that have empty space to expand to 50 or 100 stalls over time. I think the current biggest station is in Norway with 48 spaces. It is non-Tesla of course.
    (Thanks to RubberToe for reminding me of this option).
     
  2. Zextraterrestrial

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    just my thoughts ..
    1. I think it can work. All Teslas will probably have 3g or better at least for TM to monitor + if SC's are shared with other car makers they'd need to be up to the standards of the Tesla + build /pay for SC's
    2. not needed, should be in the car, not on a sign outside + useless for others(non Tesla drivers) and distracting
    3. pretty much. but not a good spot for SC's. rest areas like Oregon has, maybe. Don't know about other areas though

    in CA many stations are barely used and very few are overcrowded so far. not that big of a deal.
    Don't know the UK terrain but I'd think it should be easy compared to covering all the US or other countries
     
  3. dsm363

    dsm363 Roadster + Sig Model S

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    If there was a supercharger every 10 miles along a 100 mile stretch I don't see how it would be much of an issue for a very very long time. Also, Tesla has not indicated they plan to drop 3G/data connections in their cars. How else would they upload service updates and do remote diagnosis? Even if Tesla doesn't sell a data package, it will always likely have for the Tesla's use.
     
  4. Teo

    Teo Banned

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    Of course if Tesla can afford giving away 3G for the life of the car then great. There is no problem. #1 would work and your version of #2 (without road signs but infor on screen) would work too. But I think free 3G is unlikely because it would cost too much for Gen3 cars compared to the price of the car. They can't make 3G optional after 4 years and expect the system to work because those cars that don't have it would mess up things for cars that do.

    Now that I think about it, some smartphone app might do the trick for those who don't have 3G. You could either use the app or connect the 17" screen to your smartphone's 4G.
     
  5. dsm363

    dsm363 Roadster + Sig Model S

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    Gen III will almost certainly have built in 3G but the owner may not be able to access it for surfing the web, internet radio, Nav....unless they pay an extra fee or use their smartphone as you said for the 'extra' data connection. Tesla paying only for a few megabytes a month per car wouldn't be expensive to Tesla. Especially if they encourage wifi for software updates.
     
  6. Teo

    Teo Banned

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    DSM,

    After 4 years you could have the option to renew 3G or not renew. Those who don't renew could update software with wifi or tethering. Making 3G option doesn't break software updates but those cars that don't have it could break the system for other cars.
     
  7. RubberToe

    RubberToe Supporting the greater good

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    You are speculating about something that is several years down the road. For the Vegas example, they would certainly be able to put in a new charging station that could have 20, 50 or even 100 stalls. That isn't needed now, so Barstow only has the 4 or 6 stalls that it has. I would imaging that your speculation about reserving a stall location in advance would be the first option if there is a big shortage. That stretch of road has 4g all the way, so it will be easy to track arriving vehicles in real time. They could do it now, in 2 years it will be even simpler. All the infrastructure is already in all the cars, and will be in future cars.

    The real high capacity routes (LA-Vegas) are perfect locations for battery swap stations. Everyone going there is coming back the same way. Drop off your "owned" battery in the Barstow battery swap station and get it back on the way home. A 10 stall supercharger station can charge a car ever 4.5 minutes, assuming every car charges for 45 minutes. A single lane battery swap facility can "charge" a car every 90 seconds, say 120 seconds for the sake of argument. That single battery swap station has 2x the capacity of a 10 stall supercharger station. Looks like Tesla will start with a single battery swap station fairly soon and perfect the hardware. When they are satisfied with how it works, they will roll them out as required. Like Elon said, you can charge for "free" at the stall for 45 minutes, or "swap" your battery for a certain $$$ amount. The $$$ amount will finance the upgraded hardware required for the swapping.

    For those that don't think TSLA can pull off battery swapping stations, I would suggest that you look back at Elon's track record :smile:

    BTW, there is a 300+MW solar power plant right on the Nevada border partly owned by Google. Getting enough electrons to fill up a few hundred 85Kw batteries per day isn't going to be a problem either.

    RT
     
  8. Teo

    Teo Banned

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    #8 Teo, Jun 24, 2014
    Last edited: Jun 24, 2014
    Hmm, a free 3G for life without web. It sounds like a good idea. It would prevent lots of problems.

    - - - Updated - - -

    RubberToe,

    I agree with your mega stations idea. In fact I had the same idea a while ago and mentioned it at official Tesla forums. I forgot it when I wrote here.

    Edit: I added mega stations as one of the options.
     
  9. Chipper

    Chipper Active Member

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    Of course by then Tesla may introduce a 110 kW battery or even a 135. Who knows? And how would a battery swap station affect this "problem"?
     
  10. igotzzoom

    igotzzoom Member

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    This would be fairly easy to implement. You could potentially reserve a charging spot through an app or the touchscreen within a certain timeframe. If you don't reach the charging station within the estimated timeframe, the charger would be unlocked for someone else to use. I think some apps, like PlugShare, already give real-time availability information.

    Again, "smart" navigation, enabled by a live data connection, would mitigate this, giving near real-time updates on charging station availability. It wouldn't necessarily solve the availability issue, but would at least give you that information. GM is aggressively rolling out 4G in almost all of its models. It will probably be the de facto standard going forward. I expect the Gen-III to have 4G capability built-in. Whether or not it will be free (or rather built-in to the purchase price) is another issue.
     
  11. Teo

    Teo Banned

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    igotzzoom,

    I agree about on screen data instead road signs. I was thinking that 3G will be optional and then all those cars that don't have it would break the system. But after dsm363's idea about free 3G without web, I changed my mind. I have now updated the opening message. I think they will start with availability info on screen. Then gradually improve it and move to computer managed pre-booking system aka smart navigation.
     
  12. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    if there had been an internet available in 1890, I'm guessing we would be having the same conversation about gas stations--and roads.
     
  13. GSP

    GSP Member

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  14. Teo

    Teo Banned

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    Jerry,
    I'm guessing you skipped the long opening message and the fictitious restaurants example. Gas stations are different because even if number of cars is 3 times the number of pumps, it is still not a problem because low fill-up times. A comparison with restaurants makes more sense where the time you spend is similar.
     
  15. JakeP

    JakeP S P4996 / X P6028

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    Jerry33 for the win! Perfect synopsis of the entire conversation.
     
  16. bonnie

    bonnie Oil is for sissies.

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    Luckily, Tesla will have the luxury of being able to evaluate actual Supercharger utilization and usage pattern against sales in any particular area - and will be able to determine the right strategy based on that.

    Real data will undoubtedly drive this solution.
     
  17. Zextraterrestrial

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    ..add Space X satellites and whatever G's Elon wants to use for Tesla, game over?

    everyone says 3g is junk anyway. (don't have a cell but have tesla 3g and it is spotty in some places)
     
  18. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    This is the case now, when ICE cars were first getting started, it wasn't a five minute fill. Gas pumps were actual pumps that you had to manually pump. You pumped the gas into a clear tank up to the amount you wanted, and then you put it in the car. And there weren't any good automobile roads outside the city either.
     
  19. Teo

    Teo Banned

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    #19 Teo, Jun 24, 2014
    Last edited: Jun 24, 2014
    Bonnie, if you look at the restaurant example in the opening message the current situation is demonstrated by 15 diners and 10 chairs per restaurant and multiple restaurants. If you leave people alone and let them pick whichever location they want, the fluctuation of their random choices can't fill up even a single location in terms of probability. However if you increase diners to 150 and you still have lots of restaurants with 10 chairs each (this replicates 10 stall stations), the random choice becomes a real issue.

    Therefore data on usage alone won't help. There needs to be a way to distribute demand evenly by redirecting cars to different stations as well. If Tesla were to just monitor data they would see that some stations get 30 cars while other stations get 5 and then they reverse roles. Each station would be overcrowded and under utilized continuously.
     
  20. stopcrazypp

    stopcrazypp Well-Known Member

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    #20 stopcrazypp, Jun 24, 2014
    Last edited: Jun 24, 2014
    Even without reservations, a broadcast based system (which shows current availability at each station) can alleviate much of this. It can operate similar to the traffic report systems in most GPS (and the navigation software can suggest the best station to stop at).

    Also, instead of mega stations, Tesla can built smaller stations near each other (accessible from the same exit). Along I-5 there are many stops with multiple gas stations, so the idea is the same.
     

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