Best to share... when?

[FakeStewartAlsop]

So, I'm an aspiring Model S owner. I'm aware, that when a SuperCharger gets busy, its best to try to use unpaired stalls, since the 'A' side shares power with the 'B' side. In other words, both cars in the A/B paired stalls max out at 60kW ... which is not much of an issue if the incumbent, who first arrives to the pair, is already charged to 65% SOC or higher. This 'optimal' pairing, as I understand it, happens because the battery normally tapers its charging flow as it approaches 100% SOC and can't even access half of the current after 65% anyway.

This leads to the conclusion, that if given a choice, a new arrival to a SuperCharger should, if pairing is absolutely necessary, choose to pair with somebody who is nearly done with their charging requirements. Its good for you, the new arrival, because the other guy will leave soon, and it is no worse for him, given the limited capacity to absorb charge. Having said that, if you arrived to a Supercharger and you had only two choices of stalls to go to, which would you choose:

a) a stall paired to a Tesla without any arrival/departure or SOC information; or
b) a stall that suggests that the best time to share is in about 5 minutes (we'll call this one 'Sign Owner').​

So, given the above, assume you arrive at 11:31. Which stall do you park/charge in? Why?

IMG_7194-crop

• FakeStewartAlsop
• Mar 29, 2016

Charging signage

Does your answer change if the Sign Owner (b, above), is chronically late by 10 minutes to pull their car out of the parking stall, and you know that is the case before charging?

 

[FlasherZ]

A quick correction: Both cars do not max out at 60 kW as you suggest (the newest cabinets are actually rated at 135 kW, with maximum to one car at 120 kW). The first car to arrive gets everything it needs on the taper, with the remaining going to the second-to-arrive. Charger outputs are dynamically switched to the other car as the taper occurs. Some people abuse this by pulling in, then clicking the supercharger's button on the first car of the pair so that their car then becomes the primary car.

If you arrive at an 8-stall supercharger and all four "A" stalls are used, obviously you'd like to know which has the highest SOC - because you'll get more current to your car, the further along he is. And so without any other information, knowing their state of charge (which is sometimes conveniently displayed in the car for you to look at - even if they're gone) is the best way to hedge your bet.

It may not always be the best, though -- from St. Louis to Indianapolis, one might choose to stop in Effingham and spend only 5-10 minutes there, because you need only 5-10 to give you a safety margin to Indy where you'll settle for a long charge (dinner at the Steak-n-Shake). In that case, even though I'll arrive with a slightly lower SOC than others, I might be gone more quickly.

Bottom line: Pull into an independent charging pair if one is available, otherwise just pull in and don't worry. Taper will occur soon enough.

 

[FakeStewartAlsop]

OK, I stand corrected. Then in a pair of charging cars, the first-in gets 'all it can eat' of the 135 kW, unless somebody tampers with car1, in which case car 1 gets a sudden step-down in charging kW. At which point, a war of the clicks begins

 

[FlasherZ]

Yes. It's rather unfortunate what human beings will do to each other. "Do unto others before they do unto you" seems to be their mantra.

 

[FakeStewartAlsop]

Surely, a smart Tesla employee could whip up some SuperCharger controller code to bar spurious clicks? I mean, Tesla can afford to send out Vehicle Charging Specialists to busy supercharger sites to valet people's cars in and out of the chargers... am I right?

 

[FlasherZ]

It's for safety purposes, it must interrupt charge when the button is pushed, unfortunately. There is another thread where we discussed some anti-cheat measures that could be put into SC control software, but it's pretty rare that it happens.

 

[Boatguy]

It seems like Tesla has already addressed this communication issue:

"During charging, the charge port pulses green... The frequency at which the charge port’s light pulses slows down as the charge level approaches full. When charging is complete, the light stops pulsing and is solid green."

Why won't observing the flashing of the paired vehicles charge port communicate the status to the new arrival?

 

[FlasherZ]

It seems like Tesla has already addressed this communication issue:

"During charging, the charge port pulses green... The frequency at which the charge port’s light pulses slows down as the charge level approaches full. When charging is complete, the light stops pulsing and is solid green."

Why won't observing the flashing of the paired vehicles charge port communicate the status to the new arrival?

When the car is locked the light no longer pulses.

 

[Boatguy]

When the car is locked the light no longer pulses.

OK, sorry for the Noob ignorance.

In any case, that would be easy to change and makes more sense than owners leaving notes on the dash.

So my point is that it benefits all to know more about each other's vehicle when supercharging, and since Tesla has the information, they should share it.