Yes.
No.
By its very nature, reservations hold stalls UNUSED, and is therefore reducing the efficiency of the utilization of the resource.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Thanksgiving 2022 charging stories?
- Thread starter bradtem
- Start date
By its very nature, reservations hold stalls UNUSED, and is therefore reducing the efficiency of the utilization of the resource.
There are ways to do reservations that don't do that. In particular, this is true because with Teslas, the car/system know where you are and where you are going, and whether you will make your reservation. Particularly on long trips that means a lot of advance notice when you won't make it to allocate it to people in the virtual queue.
The main problem is what to do with people who miss their reservation through no fault of their own -- surprise traffic jams, weather, road closures etc. In this case you can either cancel their reservation to assure no wasted time on the charger, or give them some priority in the virtual queue so that they don't wait too long when they finally do get there. Either, but especially the former, mean the driver plans to get there before their reservation and leaves time in their schedule for surprises -- as you do for any hard deadline like catching a plane etc. It should be very rare that a stall just sits there waiting for the driver who reserved it.
This does mean that if a driver arrives unplanned at a stall that's reserved 5 minutes from now, they get told, "you only get to charge for 5 minutes. Be in your car waiting for the reserved driver to arrive, and if you don't, you will pay very high idle fees." That driver, waiting in their car is given an alert that the reserved driver will be there in 60 seconds and they unplug and drive out, then wait for the next free slot.
So reduction in efficiency should be slow. Of course the goal here is that a driver who does make and sticks to a plan gets a reliable experience. And other drivers who can't get a reservation modify their plans, and charge at other chargers, or drive at a different time, or wait in virtual queues for the timeslots that become available. This is only in the most overloaded times of the year. Most of the time the reservations will turn out to do nothing, you arrive at your reservation and there are multiple free slots.
Hotels also need to start making it possible to reserve chargers during the night. When I plan to stay at a hotel with charging, I will arrive at that hotel quite low, and I need that charge slot, and if I don't get it, it can be trouble -- or at best an hour delay to get to and use a supercharger in the morning. Hotel reservations though can mean inefficient use. Hotels should eventually put in *lots* of plugs, with power sharing of the plugs, so there is never not a plug, but your plug won't be full current all night if you don't need it. Alternately hotels should space out chargers so that 2-4 cars can park in range of the unit, and a hotel employee can come out in the night and swap plugs -- or get the keys and valet the cars in and out. But that costs money to have staff do that, of course, though many hotels have fairly idle night staff.
Reservations at Superchargers sound like a horrible user experience. I’m not even sure what problem such a system would solve.
For destination charging, sure, reservations could make sense, but that would also require increased patrol of ICEing so that reservation holders can be confident that their charging station will actually be available.
I’d stay at a hotel with valet charging if that becomes a thing, that amenity may attract more guests than a swimming pool.
Why a horrible experience? You would plan your Thanksgiving drive to Grandma's house for today using the standard interface of Tesla's nav planner or a web tool like ABRP. It would plot a drive for you with reservations. It would add some "slop" and you would tune that as you liked. That would mean that, if you got to your reservation area early, you might be slotted in early if there is capacity, or you might have to start your activity (shopping, charging, whatever) sooner to wait for your reservation time. Or just wait around, which is the price of having a guaranteed plan. At shared v2 chargers, the system will give you enough current for your assured reservation time, so being the first of the pair might not work quite as it does today.
If you got your stall early, the system would try to adjust your other reservations and plan for the day. If the load is very high, it might not be able to. Again, as always, you should have a flexible plan for what you are doing -- take a more relaxed meal. Have a hike. Shop a little longer. Watch a bit more Netflix. Not a lot more, just a bit more, unless you deliberately put a lot of slop in your schedule.
But again, ideally, your reservations are all being adjusted in real time as you drive so most of the time you don't even notice, you just are happy that you know a stall is there for you unless you deliberately or accidentally have a major delay.
This is no worse (in fact much better) than those who travel with deadlines, like catching trains and planes, making meetings, etc. It's hardly a new thing in general, though it's new for driving. This is only really needed for those few peak days in the year, though, and of course optional.
Last edited:
It will come, but even better will be charging systems specifically designed for hotels and EV driving guests.
- When you reserve your room, it reserves a charger for you.
- As you drive, your car communicates its expected SoC upon arrival and amount of charge needed. The hotel system plans power distribution for the night
- As you pull up your car gets a message telling you which stall to park at with a map. The unit there may display "Reserved for Genie" on it, which helps reduce Iceing problems because people are less likely to park in a space that says reserved for a named individual than one that just says generally reserved for EVs.
- The hotel system allocates power in the night to make sure everybody gets full. If there is not enough power, guests may get a message with some credit given to guests who are willing to take less energy. Ideally not.
- While ideally there are just lots of plugs and smart software, in some cases valets do the job.
Most Tesla owners are aware of the Thanksgiving overcrowding at Lunch time. Smart ones will watch their displays and charge up before the crowds arrive. Charging before 10:30 or after 2:00 will help prevent these long lines from forming.
Interesting to note that along I-5 on Holiday weekends, even the gas stations will have long lines, with hurried drivers jockeying for the fastest lines. Also long lines at restaurants at Lunchtime. Would be economically foolish for Tesla to build twice as many chargers for just these few days of the year. They would sit unused 99% of the time.
Interesting to note that along I-5 on Holiday weekends, even the gas stations will have long lines, with hurried drivers jockeying for the fastest lines. Also long lines at restaurants at Lunchtime. Would be economically foolish for Tesla to build twice as many chargers for just these few days of the year. They would sit unused 99% of the time.
The peak does't require doubling the number of chargers.
There are many costs to a charging station. One is the cost per stall. Another is the cost of the service into the station. Another is the general cost of doing a construction site, trenching, negotiating, permits etc. Once you get it down to a science, the incremental cost of a new stall gets to be a smaller portion. So adding 50% more stalls does not add 50% more to the cost of the job. Perhaps it adds a lot less. That's with the same service, so when the station is full you can't provide quite as much power to each car. But the reality is that most of the cars there can't take full power, so that can be OK. I suspect it's very rare that a station with a megawatt is delivering that megawatt even when every stall has a car in it.
So you can provision more if you want to, even for rare use. It's not free, but it doesn't anywhere near double the cost to double the stalls, and it does increase throughput to double the stalls without doubling the power -- though you probably increase the power a bit, as you factored in the power sharing when you designed the smaller station too. (Stations getting IRA money have a rule that 4 of them must be able to do 150kw full time at the same time, though in practice all 4 cars will rarely be asking for 150kw at the same time.)
And of course the actual electricity delivered is a cost that varies with usage. It actually is profitable on a gross margin basis. For Tesla of course, the value is not having lines, as lines piss off drivers who then don't buy Teslas if they happen too much.
Last edited:
Literally impossible because of the definition of reservation.
I'm definitely watching to see how today and Sunday go. As you and most agree, it seems impractical to build up I-5 to make Thanksgiving the typical no wait experience. No other interval compares. At least not at this point in time. But with the surge in sales and SC expansion, how is it looking? If I had to do it, I think I might try to avoid what I would expect to be the main bottlenecks like Kettleman coming from the Bay Area, and instead charge earlier, so I could bypass the middle zone. And since speeds are likely to be lower due to congestion, range should get me fairly close to LA for the big topoff. Maybe that means just 2 stops instead of the 2.5 I needed for my last (and only) trip since getting the MYP. ( I didn't help by doing a lot of 90+ on the way home late at night. )
How it goes informs Tesla on the need to create virtual queues or reservations, or perhaps it's simpler to just have a marked queue in the parking lot. The lack of any method relies on drivers self organizing, which is not particularly effective, leads to conflict. If I can predict I'll need 20 to wait and then another 25 to charge, I can manage that as a meal time stop. When it's completely unknown, it leads to those fears of repeating the 'I hated my EV charging experience' stories we keep reading, mostly from the CCS dependent folk.
ucmndd
Well-Known Member
I like the idea of smart queue and demand management through the car’s nav system, but it seems to me there are way too many variables and bad human behaviors to account for in the outright reservation scenario. Just too much to go wrong and diminish the experience.
if the need for strict management is found, Tesla could prevent cars without clearance from receiving any juice, and even bill them for trying. It could be as controlling as "you are now clear to go to stall 8" or more simply "you may now plug in to an open stall." It relies to a degree on people leaving the stall shortly after they unplug. But more critically, not sure how it plays with non Teslas when they become part of the customer base. How is it done in the EU? How does the SC recognize a unique non Tesla, or can it? If it can't, then any sort of queuing system seems unachievable.
That is handled differently. You are thinking plug in first, and then can the station recognize it? But there, non-Tesla car owners have to use Tesla's mobile app to select the station and then select the stall they want to use, and then activate it. So they are very directly telling Tesla that they are a non-Tesla car about to try to use that station.
from a system engineering perspective, it would have been better to make non Tesla customers purchase some sort of adapter/dongle with a serial number, so they could enjoy the same plug and play functionality. It would still be more awkward to incorporate them into a virtual queuing system as they would need to interact with the smart phone to book intent, and then get clearance, versus the Tesla nav system handling it.
You mean "literally" in the metaphorical sense, then? I use literally to mean strictly.
The definition of a reservation is a guarantee is a promise to have something available IF you show up within a time window. The reservation can vanish if you are late. So it is certainly possible to do that without generating a lot of idle time when you have people waiting, especially in virtual queues, to use up any gaps in the schedule. Oh, a few odd gaps will happen but this is unlike any other such product, because with Tesla, you know exactly where each car is an exactly when it will get to the charger, typically to the minute.
Yes, you want to give people a small grace period to be late, but you don't have to, not during crunch time. The train does not wait because you are 1 minute late. The bigger issue with reservations is the reverse -- people will feel they must not be late so they show early, and that means that having the reservation does mean some idle time -- but it's predictable time, unlike wait times during a crunch.
It's not perfect. With the closed highway problem in the central valley of 2019, everybody will miss their reservation and so everybody waits. Frankly, I am not sure how to solve the problem of a highway being closed and suddenly releasing all the EVs at once. You can improve it, by trying to distribute those EVs to all the stations they can reach, forcing people who can reach a further station to go for that one etc. You might dispatch trucks with batteries to get people enough juice to reach another charger, or also forcing people who make the charger to only spend 10 minutes to give them enough to reach a different charger. Indeed, you might create a whole new series of reservations so that you say, "OK, 5,000 cars just got released from the traffic jam and all want to charge, and you allocate a plan of reservations to give the cars just enough time at the nearby chargers to get them to assured reservations at later chargers. Nobody who is full is allowed to charge at the early chargers."
The scheduling shifts from an individual queuing entry system to one more akin to ATC for SFO when the cloud cover is high. Most people would prefer the normal first come, first served method, but the better system answer would be to prioritize by SoC and destination, and as you say, limited charging to clear the bottleneck.
The grapevine does shut down a lot, and the Tule fog is common at times of year, so the problem there is a reoccurring one. Locating SCs on either end of common roadblocks seems advisable - could direct those under 50% to immediately make use of them.
It's not clear how to solve it with pure FCFS. You could do that with a rule that says, "You only get enough to reach the next SC in your plan, sorry." And very heavy idle fees after you reach that SoC. (Or perhaps charge $5/kWh after you reach that SoC, not actually shut you down.)
But in this case the master computer in the cloud knows everything -- every car going to the chargers, what SoC they have, how much they need to get to the next charger, anticipated loads and waits at the remote chargers. It can make an optimal plan that it is unlikely any organic first come first served approach can match.
But you can also say "80% of stalls is for those who participate in the plan, 20% are first come first serve, you pick which set you want to join."
it feels like a fun problem for the machine learning programmers, both academically and for real. like with the airplane boarding challenge, a lot of theories to test out. And Tesla has the data from CA drivers to feed into the scenario. The main variable is how well or badly people will behave.
Better to solve for the system, but to date, individuals still get full free will, other than to leave their car blocking the station after the charge completes. But if the answer is choice, then there are the locations like Kettleman with two lots. One can be the free for all, and the other is the reservation only one.
We seem to be going down quite the rabbit hole, here. I'm very interested in hearing personal experiences about charging over the Thanksgiving holiday. So far, as of this afternoon, charging from Seattle to the Canadian border is holding up well - nothing is full.
No! I definitely don't. I hate that.
Of course--because that is what the word means, and that's how I'm using it.
Yes, basically. It is HOLDING the item for a SPECIFIC person. But that is why there is this unavoidable problem that this can't ever be perfectly exact timing all of the time, so there WILL be unused idle time.
Exactly. How late?! 15 minutes? 10 minutes? 5 minutes? That is some amount of time that the stall is being wasted. There are various things to try to lower the amount of time the resource sits unused but can't eliminate it if it's a reservation.
Look, this has been gone over in plenty of detail in the Supercharger queueing thread and isn't about Thanksgiving:
Supercharger queuing system
Well, you might imagine it's complex, but you would be guided through the process with the app in your phone and on the screen of the car, so it would be pretty simple to do. (The part about cars moving in and out of stalls is obviously for the future, once Tesla decides to work on actual...
teslamotorsclub.com
Queueing systems would be a welcome addition to organize or prioritize who the next person is who gets to jump into an open slot as soon as it becomes free. That would be great. But actual reservations--holding stalls for people--introduces stalls being idle, and that's definitely something to avoid.
Similar threads
