Managing a Tesla charging line
Apropos of my Thanksgiving article on EV charging shortages on peak travel days there have indeed been reports of very long waits of an hour or more at some chargers in California, though they may be partly attributed to road closures on I-5 in Southern California (or "The 5" as it is known down there) bunching up the cars. At one station with a very long wait (San Luis Obispo) Tesla brought in a portable supercharging station on a trailer, which had 8 chargers and a megapack battery. But it was gone by the time of the long wait](https://youtu.be/a1uFudf37JU), possibly to get recharged itself.
So, whatever the cause of the long wait, here are some thoughts on ways it might be made a bunch shorter, some of which would be controversial.
They would all start with Tesla managing the line, rather than having drivers queue up. This is to say that when you approached the station, Tesla would put in you a digital line, manage your place in the line, show you your place in line and fairly accurate estimated wait, and alert you which charging station to go charge at when the time came. You could only charge at that station, and nobody else could, and signs would clearly say that. Tesla knows where all cars are, and what their state of charge is, and even in most cases where they are going next. Cars are already told to signal their approach to the charger via navigation, so the car can heat up the battery to the desired temperature for charging, which speeds up the session.
There many many big advantages to Tesla managing the line. It avoids the need for a physical line, and when the line is long, drivers could go do other things, like go to a restaurant to start their meal, as long as they can pause that task to plug in when needed. Right now they must sit and wait. In addition, even without a line, Tesla can tell you which charging port to go to for maximum charge speed. It knows the SoC for all the cars in the chargers. Most Tesla chargers come in pairs which share power, and you want to either have no partner (which doesn't happen when there is a crowd) or pick the open station whose partner is almost full if you can. Tesla could do that for you. You could also indicate if you needed a handi-accessible station.
It should be noted that while some of these approaches might be complex, this complexity need not be visible to drivers. They just watch their time estimate on their car screen or app. If Tesla doesn't jockey the line positions too much, that estimate will be quite accurate -- Tesla knows who is in line, who is coming to the charger, what type of car they have and how long it will take them to get charged at the charger they are assigned. (It even knows what load the charging partner will be taking.)
The advantages grow when there is a real line, though. Tesla could manage it to get the maximum throughput in the station, which means less waiting for everybody, even those who change their behaviour a bit because of the strategy. While Tesla could just put people in a first-come first-served line, it could do more than that. To start, it could put you in the line when you are some distance away, allowing for much smarter planning. This would come at a cost to those who don't signal their desire to charge until they get to the charger, but it would mean they could redirect more distant customers to other chargers with shorter waits, or even give them overtly reduced waits in exchange for deviating their route a bit.
Likewise, it could redirect people who have enough charge to more distant chargers along their route. It could let them charge very briefly (at max charge rate) for a few minutes, and without a line, then send them to the more distant charger to wait (for a shorter total wait) there. It could even offer them a much reduced wait at the more distant charger.
But there is even more:
- Priority could be given to people out of town passing through, over locals who simply are seeking free supercharging or were lazy about charging at home.
- Priority could be given to those willing and able to only charge to 50%. Superchargers work at their fastest rate only up to 50%, then they slow down. You get the most charging delivered if everybody moves on after 50%, as long as they can make it to their next charger. Tesla can offer a shorter line at the next charger in exchange.
- Beyond that, charging beyond 70% can be forbidden unless absolutely needed.
- Idle fees can be greatly increased while there is a serious line -- with lots of advanced warning in the app, of course.
- Tesla could loan out Chademo adapters and direct some drivers to local non-Tesla fast charge stations, possibly buying exclusive use of them and managing them for Tesla owners who have or borrow that adapter.
- If there are Level 2 charging facilities available, drivers could be sent to those during their "wait" -- they may only gain 30 miles of range but it still reduces their time at the supercharger. This can be done at any such charger along the way to the supercharger, as the driver is advancing in the queue even while far away.
Money could also be involved, which would surely be controversial.
- People paying for supercharging can get some priority over those with unlimited free supercharging. Of course, if the latter wish to pay, they would not lose any priority. Tesla promised them free supercharging, but not free priority in any lines. What to do with the money? See below...
- Controversially, people could pay to jump ahead in the line, with the caveat that any such fees are put in an escrow pool allocated strictly to the building of additional supercharger facilities, or to pay for more portable superchargers to reduce lines in future.
- The more people plan their supercharging well in advance, the more readily Tesla can predict long lines and dispatch their portable superchargers. (These are trailers with 8 chargers and a diesel or battery power source that temporarily increase capacity.)
- People could also pay in to fund this extra charging capacity in advance. They would pay a lower price than the "real time" price, and be assured priority. This builds the extra capacity in advance, so while they jump the line, they are also making the line move faster for all the people who didn't pay.
- Slots could just be sold at auction. Those with more money than time would pay. Of course, some people think this is terribly unfair, and others think it is the best working system. Which are you?
- Reverse financial incentives can be given to those willing to wait longer, such as free supercharging (paid from the above fees) or discount meals. In addition, free charging at different, less busy superchargers can also push the incentive to go to them.
- People could literally buy their way through the queue by making offers. "Who will let me ahead of you (ie. 2 minutes extra delay at a big station) for $2?" If 6 people refuse and 40 people accept, the driver in a hurry pays $80 and goes to spot #7 in line. Drivers could also pre-publish the price they will accept for being bumped. (To accept money, drivers must really need charge and must complete their charge and drive a long distance, to prevent people from getting in line just to sell position in it.)
- People accepting charging at another station might be charged immediately for their session, to make sure they follow through on their reservation.
Some people say, "They should just build enough capacity" but the reality is that building capacity for extremely rare peak events is a very uneconomical thing to do. Temporary portable capacity is a better choice for localized peaks (such as one from a road closure or event.) It doesn't work as well for wide-area peaks like Thanksgiving, but it still helps -- some stations are always underutilized, even today, while some are more likely to need that extra help in a peak.
At the same time, with a proprietary network, there can be reason. The original Tesla supercharger network was way overbuilt, and sat mostly empty much of the time, but it was a key factor in getting people to buy Teslas. So it may be worth the money to overbuild it again, in advance of demand, to make customers feel secure in their purchase. In some cases, stations can't easily be expanded but more stations can go online.
Once you establish your desire to enter the queue, you will keep your place. This allows drivers on their way to a supercharger to pause and pull over to perform any user interface needed to do any of the above, such as confirm willingness to switch chargers. You don't want that happening while driving.
This approach would provide immediate benefit today. As I write this, I can see that Tesla's 18 bay Harris Ranch supercharger is full and probably has a line, while the larger Kettleman station just down the road has several empty stations. Many of those charging at Harris could have either continued past it, or taken a very short charge there and gone to a reserved bay at Kettleman to finish the charge. Earlier this weekend, Kettleman had a one hour wait due to people moving up from the snowy pass to Los Angeles.
In spite of the highly accurate estimates, some people won't be there when their space becomes available. No worries -- Tesla knows they aren't there waiting for their spot and immediately can put somebody else in the spot. They can give the other car the next slot when it gets to the stalls, or punish it with a longer wait even when it gets there. Generally, when it gets to be a few minutes before your spot frees up, you should be camping on the spot, like you do in a busy parking lot when you see people putting in groceries and about to leave. If you don't do this, you take some risk.
The question of whether passers-through should get priority over locals is a controversial one. When Tesla first created the supercharging network, it was meant entirely for people on intercity road trips -- in fact, there were few superchargers actually in the cities at all. Locals were and are expected to charge regularly at home or work. Over time, more people have purchased cars but don't have home charging, and they often use superchargers, especially when they have free supercharging. Nobody would say those drivers don't have a right to exist this way, but it is also likely that they are the causes of the full superchargers and lines which are found at certain urban chargers. If you support the "superchargers are for road trips" philosophy, it makes sense to not make people on long road trips wait in line behind locals getting their daily charging. If you are such a local, naturally you will be opposed to that. My own view is that Tesla, when it gives out free supercharging, should not allow it on the chargers within 50 miles of your home. (Paid supercharging could still be allowed there.)