How pairing at Supercharging works

[DCGOO]

What site was that? That's the first time I hear about a three way split at a Supercharger.

Fishers Indiana, suburban Indianapolis. 10 slots 1A,B,C, 2A,B,C and so forth (IDK for sure if 3 and 4 are 2-way or 3-way and a single). Have only been there once, honestly just to find it. Fourth floor of a parking garage.

 

[Lloyd]

I think your analysis is flawed. I

I do rather doubt they limit the total site power. I can't see a reason to do that. I expect they designed the installation to work with 100% load given the already noted limitation of pairs. Adding a further limit to the site would make for more complication of the design and provide little in the way of utility. Sites can have 6, 8, 10, 12 and 16 chargers that I have seen. Given that they size the number of chargers for the expected use, it doesn't make sense they would add a limitation to the overall site that would further reduce the average charging limit per car when most heavily used. I hope they wouldn't be that limited in their vision.

They do that to decrease/limit demand charges, AND at the request of the utility when usage is high and they need the capacity.

 

[gnuarm]

They do that to decrease/limit demand charges, AND at the request of the utility when usage is high and they need the capacity.

Sorry, too many unclear terms for me to get what you mean. Which type of "charges" do you mean, the verb or the noun? Who is "they" near the end of the sentence, the utility or the Tesla Superchargers?

If you are saying Tesla will roll back the charge rate because of the peak usage charges, is this documented anywhere? How do you know this?

 

[Lloyd]

They refers to the utilities you were discussing in your quoted comment, and earlier in my sentence.

I was told by Tesla employees. Take that for what you want as they (Tesla employees ) have been wrong before.

 

[Saghost]

Fishers Indiana, suburban Indianapolis. 10 slots 1A,B,C, 2A,B,C and so forth (IDK for sure if 3 and 4 are 2-way or 3-way and a single). Have only been there once, honestly just to find it. Fourth floor of a parking garage.

Are you positive? Here's the thread for Fisher. The permit shows 10 stalls on five cabinets. This photo of a car in 1A is hard to make out, but it really looks like 1B and 2A next to it...

 

[David99]

Fishers Indiana, suburban Indianapolis. 10 slots 1A,B,C, 2A,B,C and so forth (IDK for sure if 3 and 4 are 2-way or 3-way and a single). Have only been there once, honestly just to find it. Fourth floor of a parking garage.

Just looked at photos from that site on PlugShare and it's A and B. There are no Cs.

 

[David99]

Watching one of Rich's videos I saw something interesting. Internally the new gen chargers are made from 24 Amp modules. The 48 Amp charger has 2 of them, the 72 Amp charger has 3 of them. The housing is the exact same one for both.

 

[Rocky_H]

Watching one of Rich's videos I saw something interesting. Internally the new gen chargers are made from 24 Amp modules. The 48 Amp charger has 2 of them, the 72 Amp charger has 3 of them. The housing is the exact same one for both.

Yep. Early on, when the Model X first came out, people figured that out from mapping charger efficiency. They could see little peaks of best efficiency at 24, 48, and 72A, when the modules were being fully utilized but not having the next one active and partially used yet. And there have been a few cases on this forum where we've diagnosed a charger problem because the car was stuck not being able to charge at any more than exactly 24A, so it was a telltale sign of one of the internal modules not working.

 

[WdstockWizard]

Totally! I've also been saying for years that the "A" or "B" is meaningless to owners/drivers, so they should discard that labeling scheme, and just put big "1" or "2" etc at the TOP of each stall. Leave the A/B there for the technicians who need to know which is which.

I've also been saying scrap the numbers all together (you can tell the SC numbering scheme was designed by an engineer).. and just go with colors or some other highly visible indicator.. so when pulling into a location, you can easily avoid pulling into a stall color where there's already someone charging.. i.e. look for a color with two empty stalls, and use one of those for maximum charging rate.

@David99 -- great post, thanks. Makes me wonder what's happening when people report a stall charging at 50kw-60kw (which has happened to me several times recently). Maybe a broken single charging unit in the stack.

.

Right, because not everyone understands numbers but we all know what colors mean!!

 

[Rocky_H]

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Right, because not everyone understands numbers but we all know what colors mean!!

How pairing at Supercharging works
Read it. It's on page 1

 

[WdstockWizard]

It is 72 kW, not 73. 72 / 12 = 6.
Supercharger sites are fed by 3 phase power. Three chargers always act as a group to ensure all three phases are used equally. the max total of 144 kW comes from 4 groups (of each 3 chargers). 4 x 3 x 12 kW = 144 kW. 120 is the maximum per stall probably limited by switches / wire / breaker size. Urban chargers are 72 kW per stall. Again, two stalls are fed from one cabinet so the total is 144 kW.



It's sometimes the limitations found at a specific site and a matter of cost to avoid hefty peak demand charges. As mentioned, it is much better to divide the total power up to more stalls. 12 car charging at a slightly reduced rate is better than 8 car charging and 4 waiting in line getting frustrated and posting about it on social media. It is much preferable to be able to plug in and getting a coffee rather than having to wait in line. Even when all stalls are in use, there is a chance all of them combined are not reaching the max power. Two cars at a pair could be at a high SoC and thus not use the full power available. By having more stalls this extra power could charge more cars even if they are not getting the full power they could take. Also keep in mind, if you wait in line and then charge faster, you spend just as much time overall, than when you plug in and charge at a slower rate. Except it is much better to be able to plug in and do other things.

I’m with David. When it comes to charging, he da man!

I don't know how expensive those switches are compared to just adding more chargers. Tesla came up with a reasonable compromise between cost and available charge rate. Pairing made sense in the early days when the battery packs would taper down quickly. My old 85 only accepts 58 kW at 50% SoC. Today is different. A Model 3 or S/X 100 charges at around 100 kW up to 70%. There just isn't much power left the entire time a Model 3 or S/X 100 charges on the other side of the pair. Ideally a supercharger site would have all stalls connected to one big charger that can divert to all stalls individually. Every car would get the maximum rate all the way up to the limit of the site. It would not matter where you pull in. I guess that would be a wiring nightmare, though.

As for upgrading existing sites. From what I have learned, the wires from the cabinets to the actual stalls are pretty much at their limit. They are not able to sustain much more power, especially not over a longer period of time. Those are down in the concrete so they would be very difficult to upgrade. The only way to get significantly more power is higher voltage. That would require a new pack. Maybe with the Model Y and Model S refresh it will come. I believe the Tesla plug is also at the limit of what it can handle in terms of Ampere. So again, only higher voltage would enable a higher rate.

 

[David99]

Well with the Superchargers V3 the whole pairing things will be history. I believe it will take at least 2 years for Tesla to convert most sites to V3 and some will most likely just stay as they are.

 

[Saghost]

Well with the Superchargers V3 the whole pairing things will be history. I believe it will take at least 2 years for Tesla to convert most sites to V3 and some will most likely just stay as they are.

One more tool to manage network volume. They needed sites all over the place for coverage, but the ones that only see a couple cars at a time during "rush hour" won't really benefit from an upgrade anyway.

Now Tesla can strategically roll out the upgrade to sites that are heavily loaded as an alternative to opening still more sites near them, and the lightly loaded sites may get updated in a few years if they acquire more traffic volume.

 

[Fiver]

Well with the Superchargers V3 the whole pairing things will be history. I believe it will take at least 2 years for Tesla to convert most sites to V3 and some will most likely just stay as they are.

Elon time™

I doubt most will ever be converted outside of high traffic areas for a lonnnng time.

40x250kW at Kettleman? I doubt the power company can even provide that without existing external infrastructure upgrades.

 

[gnuarm]

They refers to the utilities you were discussing in your quoted comment, and earlier in my sentence.

I was told by Tesla employees. Take that for what you want as they (Tesla employees ) have been wrong before.

I think I have received as much mis-information from Tesla as I have information. As to cutting back charging speeds, my understanding is a commercial facility is charged a rate based on their peak usage. I don't think this is time oriented. Since a charging station has a fixed maximum capacity which does not have startup spikes, the max rate is set by the number of units. If they use the max rate at any one time in the month there is no cost advantage to trimming the usage at any other time in the month.

I've never seen any sign the utility asks electric consumers to cut usage at any times.... at least not in any manner that would encourage Tesla to inconvenience their customers. My utility in central VA has asked residential customers to cut back peak usage, but it is a general request they send in the morning. I'd be very surprised if there was much point in asking any business to cut usage. If they don't need the juice, why would they be using it?

 

[gnuarm]

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Right, because not everyone understands numbers but we all know what colors mean!!

Numbers are pretty easy really. But it would help tremendously if they put the chargers in a consistent order, 1A, 1B, 2A, 2B... then people's natural tendency to park apart from each other would give you 1 car per pair. I've seen chargers lined up 1A, 2A, 3A, 4A, 1B, 2B, 3B, 4B which is a bit odd.

But Tesla needs to explain to people how this works too. I am still educating others at charging stations even now.

 

[gnuarm]

One more tool to manage network volume. They needed sites all over the place for coverage, but the ones that only see a couple cars at a time during "rush hour" won't really benefit from an upgrade anyway.

Now Tesla can strategically roll out the upgrade to sites that are heavily loaded as an alternative to opening still more sites near them, and the lightly loaded sites may get updated in a few years if they acquire more traffic volume.

I don't think we are going to see many upgrades to existing chargers. If you look at what is required, it is pretty much the same as a new installation plus removing the existing equipment. Very economically inefficient. Much better to spread the wealth to new stations... at least for the next couple of years. There may be a few upgrades at high profile locations.

The reality is they need to get more chargers out there and create a highly visible presence. And they need to NOT put chargers at pay parking lots at airports!!! The only Supercharger for miles of Chattanooga is in the airport, the most inconvenient spot in the city.

 

[hiroshiy]

I think I have received as much mis-information from Tesla as I have information. As to cutting back charging speeds, my understanding is a commercial facility is charged a rate based on their peak usage. I don't think this is time oriented. Since a charging station has a fixed maximum capacity which does not have startup spikes, the max rate is set by the number of units. If they use the max rate at any one time in the month there is no cost advantage to trimming the usage at any other time in the month.

I've never seen any sign the utility asks electric consumers to cut usage at any times.... at least not in any manner that would encourage Tesla to inconvenience their customers. My utility in central VA has asked residential customers to cut back peak usage, but it is a general request they send in the morning. I'd be very surprised if there was much point in asking any business to cut usage. If they don't need the juice, why would they be using it?

What @Lloyd was talking about is true. The utilities need to manage the peak electricity usage to avoid blackouts. If your car starts charging, utilities will burn more natural gas to cope up with the demand. Consumption of electricity and generation of it must match every second, or the frequency of AC will fluctuate, or worse, cause voltage drops/rises.

Tesla chose the original design to "half" the demand charge by limiting to 135kW per two stalls. Supercharger V3 now requires 250kW per ONE stall, making demand charges roughly FOUR TIMES more expensive to them at peak.

InJapan demand charges are timed per minute, and lasts one year. That means if you use peak power for 1 min, then the next one year you have that rate (per kW base charge). Here in Tokyo demand charge for 1kW is approx 14.34 USD. With one 250kW supercharger stall, Tesla will pay 3585 USD per month per stall, in addition to "per kWh" electricity cost.

 

[Saghost]

What @Lloyd was talking about is true. The utilities need to manage the peak electricity usage to avoid blackouts. If your car starts charging, utilities will burn more natural gas to cope up with the demand. Consumption of electricity and generation of it must match every second, or the frequency of AC will fluctuate, or worse, cause voltage drops/rises.

Tesla chose the original design to "half" the demand charge by limiting to 135kW per two stalls. Supercharger V3 now requires 250kW per ONE stall, making demand charges roughly FOUR TIMES more expensive to them at peak.

InJapan demand charges are timed per minute, and lasts one year. That means if you use peak power for 1 min, then the next one year you have that rate (per kW base charge). Here in Tokyo demand charge for 1kW is approx 14.34 USD. With one 250kW supercharger stall, Tesla will pay 3585 USD per month per stall, in addition to "per kWh" electricity cost.

Unless they buffer it all with battery packs at the supercharger site.

They'd have to have a clear understanding of the typical usage and it might risk slower charging if the site gets overwhelmed, but they can give v3 speed to cars without higher demand fees using powerpacks, as long as the total usage doesn't rise.

 

[gnuarm]

Unless they buffer it all with battery packs at the supercharger site.

They'd have to have a clear understanding of the typical usage and it might risk slower charging if the site gets overwhelmed, but they can give v3 speed to cars without higher demand fees using powerpacks, as long as the total usage doesn't rise.

I think the impact of the charging load on the utilities is a bit overstated. Montgomery county Maryland is one of the richest and highly populated counties in the US. It has exactly one Supercharging station. That station could turn on 100% and back off again every hour and the power company would not even notice. EV charging is so inconsequential to the power grid that it means pretty much nothing.

Here in the US the utilities have higher charges for customers that have more erratic usage in that they charge based on peak consumption. But that is not likely to mean it would be profitable for Tesla to install battery packs. Consider they would need an equivalent pack for every car that is charging during the four hour peak time. That's a lot of batteries and right now they want to put every one they can make into cars.