Supercharger V3 Power - 1000kW?

[arnis]

Tesla already tried active cable cooling. This way they could make it thinner. Though problem is with connectors. Male and female sides.
In US there are two male pins and two female receptacles. Tesla proprietary US plug does not support coolant.
Nor does Type2. Type2 DC has two pairs of power pins.
Though it is possible to feed coolant to the socket on the vehicle side and feed coolant to the plug side from the stall.

Tesla's solution is modest and reasonable: No need to do anything. 120kW is enough.
What can be done is less tapering. 120kW from 5% up to 80% at almost all conditions would speed up charging significantly.


I know I know - other manufacturers of vehicles (and chargers) have promised a lot. But those are promises.
As soon as they get to making a real thing, they will realize, that 200kW is not going to happen in few years
at a price that is "up to Model S/X class" - one liquid cooled charging station will cost a fortune. Making thousands of those - not going to happen as nobody will be ready to pay for those saved 10 minutes per week. Only those who "will switch as soon as EV's
will have a range of 1000 miles and charge within 5 minutes" - aka poop-talkers, will. But, those are promises as well.

 

[KarenRei]

Tesla's solution is modest and reasonable: No need to do anything. 120kW is enough.

Not when you're going for mass market. Not when you're going for larger vehicles. The average person who's skeptical of EVs and doesn't want to drive around in a hair shirt is going to keep bringing up charge time issues until the number comes down. The goal is to replace the average person's car, not just EV fans.

120kW is a great starting point. It is not in any way, shape or form an ending point. And Tesla appears to well recognize this with V3.

one liquid cooled charging station will cost a fortune.

And service vehicles faster, being open for the next vehicle, and thus reducing the total number of chargers needed.

Your arguments remind me strongly of the sort of people who were insisting that 20kW or 50kW or so forth was enough. "It's modest and reasonable." "People will wait." "People don't go on long drives that often". "Higher power chargers are too expensive to be practical."

It's not, they won't, they do, and they aren't.

 

[ccutrer]

Not when you're going for mass market. Not when you're going for larger vehicles. The average person who's skeptical of EVs and doesn't want to drive around in a hair shirt is going to keep bringing up charge time issues until the number comes down. The goal is to replace the average person's car, not just EV fans.

120kW is a great starting point. It is not in any way, shape or form an ending point. And Tesla appears to well recognize this with V3.



And service vehicles faster, being open for the next vehicle, and thus reducing the total number of chargers needed.

Your arguments remind me strongly of the sort of people who were insisting that 20kW or 50kW or so forth was enough. "It's modest and reasonable." "People will wait." "People don't go on long drives that often". "Higher power chargers are too expensive to be practical."

It's not, they won't, they do, and they aren't.

You ignored @arnis's point about the taper being the major limiting factor. Of course we can keep working on increased power, but if we're tapering within 2 minutes with a 350kW charger, it's a moot point.

I'm not a scientist, but my naive thought is there are two approaches to improve the taper: better battery chemistry (seems like we have a new cure-all announced monthly, but in reality we're only making slow progress on this), or to increase cooling to keep the battery happier for longer while we charge. And how could we improve that cooling? By offloading it to the charger! Yours is a great idea - have the coolant exchange flow through the charge cord, and you also get the connector cooling for free. Which means we could use smaller wire for similar charge rates as now, hopefully keeping the overall connector size similar (adding heft for the coolant lines), or keep the wire the same size, and raise the current, with a larger overall cord.

 

[KarenRei]

You ignored @arnis's point about the taper being the major limiting factor. Of course we can keep working on increased power, but if we're tapering within 2 minutes with a 350kW charger, it's a moot point.

Taper limits are based on heat removal, just like max charge rate. Cells charge at different rates. When you try to charge a cell that can't charge any more (or is nearing its limits), the excess energy gets released as heat. At least with passive cell balancing methods... there's also active cell balancing methods (which move energy around between neighboring cells based on the difference between their charge states), but they require control circuitry on every single cell... and they still don't overcome ion mobility limits.

BTW, usually when you see those "charge in 5 minutes" or "charge in 10 seconds" things, they're usually talking about just a single cell, with no heat considerations - aka just looking at ion mobility limitations, how quickly you can get lithium into the electrolyte, through the membrane, and intercalated on the other side. Real-world battery packs are more complicated.

 

[X Fan]

I'll be quite satisfied if they continue their new build program coupled with a better service program to fix the base of 'slow' chargers (with updated SW that details current status of chargers ie 110, 60a capable).

 

[arnis]

The main reason for tapering is that maximum cell voltage (of around 4.12-4.15V) has been reached.
The better the chemistry (less resistance while charging) the higher will be state of charge when
first cell gets to this voltage.
Thermal problem is also there. Especially in warmer weather. But the main reason is voltage limit.

Coolant exchange will likely never happen. Coolant is consumable. It must be replaced every 3-5 years.
In case of coolant exchange with chargers it will be mixed. All vehicles will leave their own coolant there.
And if even one will use wrong coolant it will be a catastrophe.
Also watertight connectors, with low pressure. Coupling a hundred times per day. Servicing nightmare.

I would bring back KISS principle. External cooling is not one of them.
And, going back to the first sentence: the MAIN reason charging isn't happening at 350kW... is charge acceptance.
Not cooling.

 

[scaesare]

The main reason for tapering is that maximum cell voltage (of around 4.12-4.15V) has been reached.
The better the chemistry (less resistance while charging) the higher will be state of charge when
first cell gets to this voltage.
Thermal problem is also there. Especially in warmer weather. But the main reason is voltage limit.

Coolant exchange will likely never happen. Coolant is consumable. It must be replaced every 3-5 years.
In case of coolant exchange with chargers it will be mixed. All vehicles will leave their own coolant there.
And if even one will use wrong coolant it will be a catastrophe.
Also watertight connectors, with low pressure. Coupling a hundred times per day. Servicing nightmare.

I would bring back KISS principle. External cooling is not one of them.
And, going back to the first sentence: the MAIN reason charging isn't happening at 350kW... is charge acceptance.
Not cooling.

This is not accurate. Typical Li-ion cell charging methodologies use a dual-mode constant-current then constant voltage approach. Supercharging modifies this by using a variable-current initial step that biases the curve to be higher current while the SOC is low.

While the cell is below max voltage, you can watch the current ramp up, then taper back down. It's this downward taper portion of the curve that that people refer to, and it happens below max voltage.

Only when you hit that target voltage, does the system witch to constant-current mode. Typically this is very close to 100% SOC, however... and you notice it when your charge session will stay at a couple of amps for an extended period of time before finishing. Charging to 80-90% doesn't even get to that point, yet you've still experienced the taper.

You can see all of this for yourself during a supercharging session... the current has tapered down to less than half it's max while the pack is far below it's ~400V max:

 

[Got-EMF]

The diagram appears to show a heat exchanger specifically for external connection. This eliminates cross contamination of fluids.

Additionally, thermal management also includes warming the battery when cold.

One could cool the cable while warming the pack at the same time if need be.

 

[Big Earl]

Bumping this old thread because it seems like the most relevant place to post.

Thinking about SCv3, I think it will go one of two ways, as described below.

Currently, Superchargers are made up of a stack of twelve 40 amp chargers (like you'd find in classic Model S) at 277 volts (277/480), providing a max output of about 135 kW. Tesla could upgrade those to the new 48 amp chargers and get a maximum rate of 160 kW or upgrade them to 72 amp chargers for a maximum rate of 240 kW.

If they go this route, existing locations could easily be upgraded. However, existing stations have transformers and switchgear designed for the existing load. I haven't come across very many installations with a transformer that exceeds the current system specs, and in some cases, falls short of the theoretical full load. An example of this is Springfield, VA, which has 9 Supercharger cabinets (1,200 kW) on a 1,000 kVA transformer.

Thoughts?

 

[KarenRei]

V3 us expected to use battery banks, such as power packs, which will in turn charge vehicles, such as with DC/DC converters.

The existing cabinets could of course charge the batteries.

 

[arg]

Currently, Superchargers are made up of a stack of twelve 40 amp chargers (like you'd find in classic Model S) at 277 volts (277/480), providing a max output of about 135 kW. Tesla could upgrade those to the new 48 amp chargers and get a maximum rate of 160 kW or upgrade them to 72 amp chargers for a maximum rate of 240 kW.

The first generation superchargers (max 120kW output per cabinet) were built from the charger modules out of the original N.America Model S. These had an architecture where their main limiting specification was their input current (40A) and hence power went up with voltage - they delivered about 9kW per module at 240V input (240V*40A*91% efficiency), but about 10kW output per module when driven at 277V in superchargers.

The second generation superchargers (max 145kW output per cabinet) were then built from the charger modules introduced with the EU-spec Model S. These again had an input-current-limited architecture, this time 16A three-phase, and 11kW input at nominal 400/230V, going up to 13kW input/12kW output per module on 480/277V in superchargers. This was an easy upgrade in the supercharger design, as the charger modules were mechanically the same (fitting in the same mechanical space in the cars).

The new charger modules introduced with Model X/facelift S were not such a straightforward upgrade - they are a different shape, and they also have a different architecture such that the overall power is limited rather than just the input current and they don't give a proportional increase in power by stepping up the voltage as the old ones did. 12 of the new modules would still be an upgrade - probably about 180kW output compared to the 145kW of Gen2 superchargers, but would have needed a new cabinet design and evidently Tesla didn't consider this worthwhile.

In the early days, building the superchargers (manufactured in 10's) out of the charger modules from the cars (manufactured in 1000's) was a huge win in economies of scale. Nowadays with superchargers being built in higher volumes, it would still be an advantage but not such a dramatic one. Tesla also have other product lines to share with - commonality with parts used in the energy storage products might be a better fit than sharing with the cars.


Personally, I'm not anticipating Supercharger V3 as offering a material change in output power to the cars - this is limited by the batteries and it's fairly clear that the existing cars can't take a huge increase. There's signs that the Model 3 could take a little more, and possibly the P100D too, but not by a huge margin - maybe 10%-20%. There's also the connectors to consider; in Europe Tesla are transitioning to the CCS connector which are only rated for about 150kW at the voltage Tesla cars use (even with water cooling), while the Tesla N.America charge connector is already pushed quite hard at current supercharger levels. They can't readily go higher while keeping the existing battery voltage, and there's no incentive to go to higher voltage when the batteries can't take any more total power for cooling or electrochemical reasons.

Tesla Semi is the one application they have for significantly higher per-vehicle power output, but indications are that at least the prototype of the Semi has 4(?) separate batteries rather than one huge one - with a connector that has multiple pins for multiple channels of power delivery, currently charged by connecting to multiple superchargers at once.

So, a bump to 150kW maximum at the car might be sensible to give a little headroom above the capabilities of current cars while remaining feasible with the connectors they have to use.

The big change I am expecting with V3 is an architecture more suited to the large sites that are standard nowadays - rather than just sharing one cabinet across two stalls and the inconvenience if users end up 'paired' suboptimally, have one larger cabinet powering many stalls (and the same large cabinet would suit charging a Semi). Other architectural changes are possible - maybe the charger output modules sharing a high voltage DC bus with battery storage, maybe high-voltage electronics to run directly from 11kV rather than stepping down to 480V with transformers. Again, this stuff probably has synergy with what they are doing in the PowerPacks in the energy storage business.

Solar could be part of the package, but that's really window-dressing rather than an important part of the technical package. When they were building 2-stall sites with low utilisation, on-site solar could make a significant impact. Nowadays, with much larger sites and higher utilisation, the proportion of the required energy that can be generated by panels over the stalls is tiny. It's a nice-to-have: if the energy generated can pay the costs of giving you shelter from sun/rain by having a canopy then that's a win, but most of the energy is going to be generated elsewhere.

 

[KarenRei]

Personally, I'm not anticipating Supercharger V3 as offering a material change in output power to the cars - this is limited by the batteries and it's fairly clear that the existing cars can't take a huge increase. There's signs that the Model 3 could take a little more

Ignoring that Tesla has previously stated that all of their current vehicles are charger limited, not pack limited... and ignoring that you can clearly see where the charger current limit ends and where battery limits begin on the charger curve, and extrapolate that backwards.... Model 3 in factory mode says that the pack can take up to 525A. That's what the computer itself says. Might there be some other limit elsewhere? Sure, there could be. And surely currents that high would only be at the bottom of the SoC curve. But that's in no way "a little more".

, and possibly the P100D too

100kWh packs are the only types Tesla makes for S/X now. And they show a similar curve as the 3, and also fall under Tesla's past statements.

Heck, both S and X have already been shown to take more than superchargers and deliver. Model 3 charged at 126kW on a FastNed 175kW charger (again, charger current limited, not vehicle limited), and similar speeds were seen on a Model X in China, similarly limited. So sure, this doesn't tell us the upper bound, but it extends the lower bound.

Tesla Semi is the one application they have for significantly higher per-vehicle power output, but indications are that at least the prototype of the Semi has 4(?) separate batteries rather than one huge one - with a connector that has multiple pins for multiple channels of power delivery, currently charged by connecting to multiple superchargers at once.

Semis will not be stopping at Supercharger stations. What, you want them to block half the station? The prototypes have only been stopping there by necessity.

Solar could be part of the package, but that's really window-dressing rather than an important part of the technical package.

Totally disagree again (at least from the perspective of large scale solar, rather than just a little solar roof). Solar power generation costs now are dirt-cheap, but this is tempered by its high grid overhead costs. Pairing a small solar farm with a battery-backed Supercharger does the following:

• Direct DC/DC solar conversion to the powerpack(s)
• Solar is buffered by the powerpack(s) (e.g. against clouds, etc). Powerpacks also offer some limited evening timeshifting.
• No grid connection costs for the solar
• Powerpacks do double-duty - converting / storing the solar, and doing DC/DC higher-power charging for vehicles.
• Higher charging powers = less vehicle time per stall = higher Supercharger throughput = lower capital costs per vehicle
• Solar offsetting daytime (peak) energy consumption, and powerpacks buffering out peaks, dramatically reduces demand charges (aka, the really expensive part of operating a Supercharger)

 

[arg]

Model 3 in factory mode says that the pack can take up to 525A. That's what the computer itself says. Might there be some other limit elsewhere? Sure, there could be. And surely currents that high would only be at the bottom of the SoC curve. But that's in no way "a little more".

Fair enough, 525A at the bottom SoC would mean 180kW, which I agree is more than "a little more" - it's 50% more. But it's not really "huge", and it's only for a few minutes at the lowest SoC.

If your figure is correct, then they could potentially enable 180kW charging for Model 3 in the V3 supercharger. However, it wouldn't serve much purpose - running at that rate for a few minutes at the very bottom SoC saves maybe 2 minutes compared to 120kW and perhaps 20 seconds compared to 150kW, all assuming you have the ideal conditions to get the best possible charge rate (SoC, battery temp, car age, power sharing etc). For the user, that's insignificant compared to the potential gains from more even sharing between the cars at a site which can make 10's of minutes difference to charge times.

You might say, "ah, that's just today's model 3, future cars will make better use of the 180kW", but that's ignoring the issues of cable and connector, where you might just squeeze 525A for a few minutes through a connector rated at 400A, but that doesn't give you the ability to run long enough to make it actually useful (and if you are running the connector at the temperature limits to achieve the 'party trick' of 525A for a couple of minutes, that may slow the charge overall if you then have to throttle the power because the connector is overheated).

It's possible they could go back to actively cooled cables/connectors to achieve a genuine 525A. But as above, that gives a trivial benefit for current vehicles (though potentially more for the future) at significantly higher cost in both installation and maintenance - which is contrary to the stated aim of Supercharger V3 to improve costs.

They might still have done it for bragging rights, but Porsche have claimed the high ground there and there's no way Tesla can beat them on that particular metric (instantaneous charge speed) - getting to 350kW with the existing cars is just not plausible. So they need to change the focus to overall performance and experience - yes, Porsche can install a couple of stalls that can go up to 350kW occasionally, but Tesla can cost-effectively install 50 stalls that deliver a consistent charging experience to large volumes of cars.

So, I stick with my prediction of about 150kW at the car. Could possibly be as high as 200kW, but very unlikely to be higher.

The kW per cabinet figure could be much more interesting. The ABB chargers to deliver Porsche's 350kW are huge - output 160kW per cabinet and a cabinet 2103 x 1170 x 770mm = 1.89m^3, compared to Tesla's V2 supercharger at 145kW per cabinet and dimensions 920 x 820 x 1800 = 1.36m^3 - so Tesla are ahead even with the V2; I'm looking for an even more impressive power density figure for the V3.

 

[arnis]

I'm pretty sure SuC v3, for Tesla owners, will mean less problems with sharing a charger.
I believe this is easily done with
a) upgrading to 800-1000V support and
b) having one, much more capable chargerstack (300-400kW) that is made out of newer charger units and
c) connecting one charger unit to 4-8 stalls.
Last one raises SuC throughput without making it significantly more expensive.

b allows semis to visit the same chargers. There is no reason to have another charging network called Tesla SemiCharger.
Just separate parking spots/stalls that are for huge vehicles, similar like this:

 

[KarenRei]

Bob heads out to his car in the morning to drive to a business client.
Bob realizes that he forgot to plug in his car after a long drive the other day, and the battery is nearly empty. Stupid, stupid Bob!
Bob stops at a Supercharger on the way to his client (250Wh/mi / 155Wh/km) to add 55km/35mi of range, enough to feel comfortable of making it there and back to a place where he can charge. This takes him:
A) At an average of 110kW (counting rampup time): Bob shows up 5 minutes late to his client
B) At an average of 160kW (counting rampup time): Bob shows up 3 minutes late to his client.
On V2, Bob shows up in 2 minutes (60%) later to his client than on V1.

Alice is on a ~1300km/800mi road trip. 250Wh/mi, 310mi range.
She sets out at 10 AM and wants to get to her destination quickly. The driving time alone will take 11 1/2 hours.
It's about 160km/100 miles between Superchargers that Alice would like to stop at in the area she's driving in, so she'll be stopping 8 times.
Alice never wants to drop below 55km/35 miles range as a safety buffer.
Alice stops to charge at around 55km/35 miles (11,3%) and finishes her charges around 215km/135mi (43,5%)
A) At an average 114kW (counting rampup time): Alice finishes charging in 13 minutes. Her total trip charging time is 1 hours 44 minutes.
B) At an average of 147kW (counting rampup time): Alice finishes charging in 10 minutes. Her total trip charging time is 1 hour 20 minutes.
On V2, charging time is 29% more than on V3.
On V3, Alice gets to her destination at 10:50 PM. She's in bed at 11:50 PM. On V2, she gets to her destination at 11:14 PM. She's in bed at 12:14 PM.
On V3, Alice gets 24 minutes more sleep than on V2.

(Alice could have gotten there even sooner if she had been stopping more often than 160km/100mi, if she was really in a rush and the network was dense near her E.g. a person charging every 50 miles would spend ~40% longer on V2 than on V3 (although you start to rack up stop overhead, so there's a point of diminishing/negative returns) )

No, it's not "world changing", but it's not insignificant. All reductions of charging time are important steps toward "mainstreaming" EVs to the general public.

(And yes, I'm aware that not everyone wants to rush on trips, and that taking long relaxation / meal breaks is good for your mental state, and so on and so forth. But trying to explain that to non-EV people usually doesn't go over as well as one might hope. And sometimes you are in a rush)

 

[KarenRei]

There's also the issue that taper rates aren't locked in stone. Tesla can and almost certainly will (as they've done in the past) reevaluate taper rates vs. degradation over time, and adjust the charging curve appropriately. They have to be conservative in the beginning, but if the current generation's chemistry proves to be holding up well, I wouldn't be surprised to see them extend the curve.

A bigger question IMHO is whether they'll overcome the "cold battery heating delays" that have been problems for some people. High charge rates are useless if the pack can't accept more than a trickle until it warms up.

 

[scaesare]

Bob heads out to his car in the morning to drive to a business client.
Bob realizes that he forgot to plug in his car after a long drive the other day, and the battery is nearly empty. Stupid, stupid Bob!
Bob stops at a Supercharger on the way to his client (250Wh/mi / 155Wh/km) to add 55km/35mi of range, enough to feel comfortable of making it there and back to a place where he can charge. This takes him:
A) At an average of 110kW (counting rampup time): Bob shows up 5 minutes late to his client
B) At an average of 160kW (counting rampup time): Bob shows up 3 minutes late to his client.
On V2, Bob shows up in 2 minutes (60%) later to his client than on V1.

Alice is on a ~1300km/800mi road trip. 250Wh/mi, 310mi range.
She sets out at 10 AM and wants to get to her destination quickly. The driving time alone will take 11 1/2 hours.
It's about 160km/100 miles between Superchargers that Alice would like to stop at in the area she's driving in, so she'll be stopping 8 times.
Alice never wants to drop below 55km/35 miles range as a safety buffer.
Alice stops to charge at around 55km/35 miles (11,3%) and finishes her charges around 215km/135mi (43,5%)
A) At an average 114kW (counting rampup time): Alice finishes charging in 13 minutes. Her total trip charging time is 1 hours 44 minutes.
B) At an average of 147kW (counting rampup time): Alice finishes charging in 10 minutes. Her total trip charging time is 1 hour 20 minutes.
On V2, charging time is 29% more than on V3.
On V3, Alice gets to her destination at 10:50 PM. She's in bed at 11:50 PM. On V2, she gets to her destination at 11:14 PM. She's in bed at 12:14 PM.
On V3, Alice gets 24 minutes more sleep than on V2.

(Alice could have gotten there even sooner if she had been stopping more often than 160km/100mi, if she was really in a rush and the network was dense near her E.g. a person charging every 50 miles would spend ~40% longer on V2 than on V3 (although you start to rack up stop overhead, so there's a point of diminishing/negative returns) )

No, it's not "world changing", but it's not insignificant. All reductions of charging time are important steps toward "mainstreaming" EVs to the general public.

(And yes, I'm aware that not everyone wants to rush on trips, and that taking long relaxation / meal breaks is good for your mental state, and so on and so forth. But trying to explain that to non-EV people usually doesn't go over as well as one might hope. And sometimes you are in a rush)

 

[arg]

No, it's not "world changing", but it's not insignificant. All reductions of charging time are important steps toward "mainstreaming" EVs to the general public.

Your Bob example is meaningful, but actually he arrives 8 minutes late rather than 10 minutes (or worse).

In your Alice example, she'd have shorter journey time by stopping less often.

It's extremely rare to find a supercharger you can get in and out in less than 5 minutes excluding charging time. Many sites are worse relative to routes you are likely to be traveling.

Given that it's impossible to achieve substantial amounts of charge in a minute or two, chasing ever faster charging (and making people pay the costs accordingly) isn't really a win. Even at current charge rates, when traveling with the family I have almost always found that the car has more charge than needed before the passengers are ready to get back on board. Occasionally I'm in "Bob" mode, but even then I usually want a coffee while I'm waiting.

It's technically infeasible to make EVs like petrol cars. "Mainstreaming" has to be about education rather than making EVs closer to petrol cars - if you don't change the expectations, saying "look! It's now only 5 times worse than your petrol car, rather than 8 times!" doesn't win the argument.

There are lots of things holding up mainstream adoption, but shaving a couple of minutes off best-case charge times doesn't solve any of them. Making charging more consistent - in terms of availability and rate is more important. Solving the issues of people who can't charge at home is the toughest one in the charging area, where the cost of provision is the real challenge.

 

[arnis]

There's also the issue that taper rates aren't locked in stone.

And how can one change internal resistance with software?
Have you ever monitored Tesla's cell voltages during SuperCharge?

 

[Big Earl]

Hi all, thanks for the thoughtful discussion, technical explanations (thank you, arg) and math problems. I’m Alice in Karen’s example, although we run from 12 to 50 or 60% because travel speeds are around 80 MPH and a bit more energy is required.