Tesla needs 200kW Superchargers for A+B pairing and future proofing.

[green1]

I think the attempt at battery swap stations was supposed to help mitigate some of the overloading of SCs and expedite those that are in a rush or maybe dont want to wait in line as they get more popular. However the quite test run and likely higher cost deterred people from pursuing it any further. Maybe it will be revived in the future.

I don't think Tesla ever really wanted to do battery swap, they did it for the CARB credits, that's it. And all they needed for that was one station, so that's all they built.
Tesla's opinion is that Superchargers are all you need. I agree. I see very little benefit to the pack swaps.

 

[daxz]

I simulated some scenarios:
Assume a S70 and S85 meet at a charger at same time and S70 plugs in first. The S70 needs 90% and a S85 needs 80% to be safe to get to next charger.
A S70 charges 0-90% ~ 43 minutes when alone
A S85 charges 0-80% ~ 44 minutes when alone

So the extra time the S85 in the "B" slot would take is:

kW     B extra Minutes
110	34
135	23
150	16
175	 8
200	 3

So upping the max charge rate to 200kW for a pair would be beneficial for the second car being charged.
The slope of line of the Charger size vs time saved starts gaining less and less around 175kW, anything more then they might as well take away the pairing.
Adding another stall to the pair (trio) with 200kW charge would mean Car B takes 3 more minutes and Car C (S85) would take 31 more minutes then when charging solo.


assumptions:
polynomial curve x=Percent from Kim.T's graph for S70: 0.00000003350003971 *x^5 - 0.00001321346353 *x^4 + 0.001821921886* x^3 - 0.1071476344 *x^2 + 1.406596214 *x + 108.9813348
S85 has same curve as S70
S70 has 68kWh 0-100%
S85 has 78kWh 0-100%
135kW is fully available to cars
(no losses from other draws (heaters/AC/...))

 

[ratsbew]

A 200kW Supercharger with A+B+C stalls would give about 67kW per stall if all three cars could take that much. In a two car scenario, the first car arriving could take max rate (120kW) and then the remaining (80kW) could go to the second car. As the first car tapers, the second car could ramp up until it too has to start tapering. A third car that shows up could have the remaining capacity which should ramp up as the first two cars take less and less charge rate. By the time the first car leaves, the second and third cars will be well into their taper and a new fourth car should have plenty of rate.

There are lots of ways to arrange this and I'm sure the Tesla engineers decided that 135 with A+B is the most optimal.

This doesn't become much of an issue until some miracle batteries that can take 5C charging from 0-100% in which case we'll need some 500kW chargers per stall for 12 minutes to charge 100kWh batteries.

 

[brkaus]

Interesting analysis for the worst case!

I would have to imagine the assumption that both cars arrive at the same time is not typically the case. Even if there was a super long line that all arrived at exactly the same time, the first two would finish 23 minutes apart and the rest would be skewed from that. By how much, I have no idea were to even start calculating that

I simulated some scenarios:
Assume a S70 and S85 meet at a charger at same time and S70 plugs in first. The S70 needs 90% and a S85 needs 80% to be safe to get to next charger.
A S70 charges 0-90% ~ 43 minutes when alone
A S85 charges 0-80% ~ 44 minutes when alone

So the extra time the S85 in the "B" slot would take is:

kW     B extra Minutes
110    34
135    23
150    16
175     8
200     3

So upping the max charge rate to 200kW for a pair would be beneficial for the second car being charged.
The slope of line of the Charger size vs time saved starts gaining less and less around 175kW, anything more then they might as well take away the pairing.
Adding another stall to the pair (trio) with 200kW charge would mean Car B takes 3 more minutes and Car C (S85) would take 31 more minutes then when charging solo.


assumptions:
polynomial curve x=Percent from Kim.T's graph for S70: 0.00000003350003971 *x^5 - 0.00001321346353 *x^4 + 0.001821921886* x^3 - 0.1071476344 *x^2 + 1.406596214 *x + 108.9813348
S85 has same curve as S70
S70 has 68kWh 0-100%
S85 has 78kWh 0-100%
135kW is fully available to cars
(no losses from other draws (heaters/AC/...))