-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
True, but we're not "almost noone". We're a bunch of Model S owners having a fairly technical discussion about the charge rate limits of our electric cars and the extent to which the need to balance the three phase supply from which the charger is powered may or may not affect the ability for power to be split between two vehicles. Inside this conversation, on this forum, the correct units to use are kW and kWh.
I think you've misunderstood how the car translates kW into mph. It doesn't factor your driving style in at all. If you configure your car to show rated miles then when you charge at 50mph that's 50 rated miles in one hour not 50 of your miles. If you configure your car to use ideal miles then when you charge at 50mph that's 50 ideal miles per hour. It is never 50 of "your" miles per hour.
As a UK owner all the people I talk to about the car know absolutely nothing about it, and have certainly never seen one before. They usually start by asking if it's a hybrid, and then when they discover it's all electric they want to know if it's fast enough to go on motorways, and how far it can go before it has to be put on the back of a truck. Of course I use mileages as easy units when explaining stuff in this context. I tell them it has a range of 250 miles when full, that all the motorway service stations in the UK have free charge points today that can put "half a tank" back in the time it takes to eat a fast food meal (CHAdeMO points; obviously I don't go into details about adaptor supply delays etc) and that Tesla are building a network of even faster (but still free) chargers that will half fill the car in less time than it takes to go to the toilet and buy a coffee. And then I tell them that they're thinking about it backwards, because where they're focussing on the perceived pain of road trip recharging, they should instead be focussed on the fact that I effectively have a gas station at my house, and a butler who carefully fills the car back up for me so that every single morning I leave home with a full tank.
Last edited:
Cottonwood
Roadster#433, Model S#S37
This picture and some other information about the Supercharger construction give pretty strong evidence that the maximum Supercharger rate per car for the next few years is going to be 120 kW. For an 85 kWh MS, that charges at 300 DC Wh/mi, that is a 400 rated mph charge rate.
Read the label that the maximum charger Voltage is 410 Volts. The 85's today finish their charging (100%) at just over 400 Volts, typically 402 or 403 Volts. That tells me that Tesla will not be increasing the number of cells in series (max Voltage) to go to larger packs; they will do it with more energy dense cells or more cells in parallel. A battery pack with a higher full charge would not be able to get a 100% charge on an ever growing set of existing Superchargers.
These batteries that go to just over 400 Volts at full charge, can accept max power when they are almost empty and are close to 360 Volts. Therefore, max charging power will happen at about 360 Volts.
The label says that maximum continuos current is 330 Amps. The screen shot shows 341 Amps, and there have been reports of 333 Amps being the typical max. Guess what? 360 Volts times 333 Amps is 120 kW.
The 333 Amp limit seems to be an assumption in the Supercharger construction, and I bet the wiring of the car. If you look at some of the detailed U.S. construction documents, the wire from the Supercharger Cabinet to the Pedestal is 350 mcm copper wire; Look that up in the NEC, and it is limited to 350 Amps. Inside the car, Tesla does not have to meet NEC rules and typically runs the wiring a little harder, but I would bet a case of goos Scotch that the wiring in the cars built today is limited to somewhere close to that 333 Amp mark.
There is a lot of momentum developing with this 400/360 Volt limit and the 333 Amp limit. That momentum will keep the max charge rate at 120 kW for many years.
In reality, this is not so bad. Because of the taper, a 90 kW limit only adds 5-10 minutes to the charge time vs 120 kW on an 85 kWh battery. Going to a 110 kWh battery, charged at 120 kW, would give you Supercharger charge times like an 85 kWh battery with a 90 kW limit. The really good thing is that 120 kW charge rate would keep going for a longer time before the taper hit.
Like I wrote
The picture is from the supercharger in Åmot in Norway.
No reports abow 330A in norway on the new 135 kW chargers.
All new SC in norway is conected to step up transformer 400 to 480v and they again gets power from a 400v transformer from the grid.
341A is reported in Midlefart in Denmark, but no pictutes from the SC spesifications.
Have seen screen shots with 348A current at this location.
This can be a diferent SC type or the step up transformers used in Norway can be the bootleneck.
Have not seen pictures of step transformers in Midlefart (Denmark).
Max power on a S85 is reported at 370v and 122kW, it had started to step down and was just below 330A.
A S60 got 116kW on the same SC and that is quite high.
Since the SC in Norway uses step up transformers to 480v I guess that they is using US chargers and not the EU models that is designed for TN and IT grids.
The EU chargers is splitt into 3 sub chargers that can handle 16A each (13A before the hardware fix/upgrade)
On both power systemd the chargers is feed with 230v.
One fase with IT grid (most parts of Norway)
IT net get max 7.4kW with UMC 32A x 230v
TN
3 fase 230v = 11kW with UMC.
16Ax3x230v = 11kW or
16Ax400v x 1.73 (120 degrees between fases)
TN have 400v between L1-L2, L2-L3, and L1-L-3 and
230v (Tesla use this) between L1-N, L2-N and L3-N
If EU chargers was used in the SC why step up to 480v?
sigurdi
The picture is from the supercharger in Åmot in Norway.
No reports abow 330A in norway on the new 135 kW chargers.
All new SC in norway is conected to step up transformer 400 to 480v and they again gets power from a 400v transformer from the grid.
341A is reported in Midlefart in Denmark, but no pictutes from the SC spesifications.
Have seen screen shots with 348A current at this location.
This can be a diferent SC type or the step up transformers used in Norway can be the bootleneck.
Have not seen pictures of step transformers in Midlefart (Denmark).
Max power on a S85 is reported at 370v and 122kW, it had started to step down and was just below 330A.
A S60 got 116kW on the same SC and that is quite high.
Since the SC in Norway uses step up transformers to 480v I guess that they is using US chargers and not the EU models that is designed for TN and IT grids.
The EU chargers is splitt into 3 sub chargers that can handle 16A each (13A before the hardware fix/upgrade)
On both power systemd the chargers is feed with 230v.
One fase with IT grid (most parts of Norway)
IT net get max 7.4kW with UMC 32A x 230v
TN
3 fase 230v = 11kW with UMC.
16Ax3x230v = 11kW or
16Ax400v x 1.73 (120 degrees between fases)
TN have 400v between L1-L2, L2-L3, and L1-L-3 and
230v (Tesla use this) between L1-N, L2-N and L3-N
If EU chargers was used in the SC why step up to 480v?
sigurdi
Last edited:
While trying to sleep a thought came to me:
I have IT grid and 240v is my regular voltage (short cable to the transformer)
The Tesla EU chargers have no problem to support this.
What if the EU SC have to chargers in serial connection to lower the current and rises the voltage to 480v?
They have calculated the power drop or power loss in the transformer so with 192A (192A/16A = 12 chargers) each charger deliveres 11.25kW
Eache charger takes 3fase, but the SC could then only dedicatd two and two chargers to eache car.
22.5, 45, 67.5, 90, 112.5, 135kW
When considering efficiency in the chargers you are down to around the 120kW people get.
I have IT grid and 240v is my regular voltage (short cable to the transformer)
The Tesla EU chargers have no problem to support this.
What if the EU SC have to chargers in serial connection to lower the current and rises the voltage to 480v?
They have calculated the power drop or power loss in the transformer so with 192A (192A/16A = 12 chargers) each charger deliveres 11.25kW
Eache charger takes 3fase, but the SC could then only dedicatd two and two chargers to eache car.
22.5, 45, 67.5, 90, 112.5, 135kW
When considering efficiency in the chargers you are down to around the 120kW people get.
Last edited:
reading through this thread the level of knowledge here is definitely beyond my mine. nonetheless, I think I've been able to pick up from your discussion something that I've long wondered about... why Tesla can't simply treat the battery pack as if it were four packs, and quadruple the charging rate with four cables hooking up to the car at 135 KW each. If an 85 kWh pack were treated like 4 21 kWh packs, hooking up 4 135 KW cables would have a "C rate" close to 7 which is WAY beyond what the battery chemistry can handle. Do I have that right?
For the most part. JB has said in the past that their engineers believe they could push the envelope a bit to allow charging to go 2-3x faster. I'd imagine having infrastructure to support it becomes challenging from the grid.
360 kW x 5 cabinets across 10 parking spaces = 1.8 MW. That's roughly what we provisioned entire data centers with a few years ago, concentrated to a few hundred sq ft.
Thanks Flasher.
I was aware JB said a year or two ago that they hope to get down to 5-10 minute SuperCharging. My recollection was that he described it as challenging and nothing that will happen any time soon. I hear what you are saying re the infrastructure challenge. My sense of JB's comments was that it was more of a technological advancement Tesla would need to make. I'm wondering if this is mostly about a new battery chemistry.
fwiw, I think a substantial increase in SuperCharging is the biggest open question where progress can accelerate EV adoption. To me it's nearly a given that range will get to at least 350 miles, probably 400 miles, by 2020. With that, I think the only thing ICE has on BEV is refuel time on a road trip. 80% recharge in 15 minutes would make a huge dent in this, let alone, 5-10 minutes. At that point I think only the ICE true believers would not recognize BEVs as the future.
I might push back a bit on that.
For road trips, I suggest that Tesla needs to "eek out" only about 40 more miles of "rated range" (permitting 250 miles of highway speed-limit driving) before the comfort level reaches all but the most crazy, catheter-wearing road warriors, provided that the Supercharging can occur in 10 minutes. Stopping for 10 minutes every 250 miles is well within reason, unless you're purposely looking for a reason to pan EV's. I'd even welcome pushing the envelope on battery longevity in exchange for a "super-supercharge" mode.
I argue that today is ALMOST "good enough" - if Tesla were to push the envelope on the taper curve at Superchargers just a bit more, I think it would fix the experience for we early adopters.
Case in point - when I travel to the Wisconsin Dells, I leave after school with the kids and we stop in Normal, IL for dinner. I do a full range charge and we spend 30-40 minutes at one of the restaurants... that's not a big deal. Then we skip Rockford and stop in Madison, WI (196 mi from Normal) right around 10:30 or 11 pm. This is a time of night when I don't really want to spend the 30 or 40 minutes in the only place open nearby (Buffalo Wild Wings) with 4 cranky, tired kids. I really need faster charging here, so that I can sit in the car for 10-15 mins, clean out the trash, go to the restrooms, then get back on the road for the final leg (less than an hour).
I guess I wasn't clear enough... I very much agree with you actually! 250 miles of real highway speed driving range would be great, and I think Tesla is quite likely to get there by 2020. as that's looking pretty good, I say developing 10-15 minute SuperCharging is really the biggest opportunity Tesla has on its own to accelerate winning pervasive public enthusiasm for BEVs whose execution/timing remains something of a question mark.
fwiw, I wrote 350 miles, or 400 miles, as an idea of where I see rated going based on 1) recent comments from Elon, 2) real highway speeds, and very cold weather will knock off 100 miles of range. if we are talking about SuperCharging to 80% (to avoid nearly ~doubling charge time on the road), I see a case for the 400 mile battery to allow for something close to 250 miles for the times all these variables are at play.
Danal
electricmotorglider.com
Exactly.
Until chemistry RADICALLY changes, the topmost 20% or even just the topmost 10% is out of consideration for any kind of "fast" charge mode.
brucet999
Active Member
Interesting example, but I think you had 175km maximum driving range of a Leaf in mind, not miles (108). Chademo 50kw charger (in US, at least) puts out about 44kw, so could charge a Leaf to only 99 miles of range in 1/2 hour.
- - - Updated - - -
That is a nifty way to put it. Well done.
Thanks for the picture of the nameplate on the EU SC, sigurdi. That answers a lot of questions. These are likely the same specs as the US units, and can only put out their full output when sourced by 480v. (Thus the need for the boost transformer in EU) The 135kW rating is a bit disingenuous, as that's it's max consumption, not what it can put out. Traditionally power supply ratings are the output power rating, which in this case must be somewhere around the 120kW figure that people have been mentioning. That would mean the system is about 89% efficient which is really close to my 90% guesstimate. I knew it couldn't be higher than 95% for sure. That also means that there is a fan blowing out around 15kW of heat when that thing is at full power! (That's about 10 electric space heaters worth, at least here in the states)
After seeing thermographs of the SC connector plug and vehicle inlet, I can only conclude that pushing 330A through there is probably producing so much heat, that is likely the limiting factor. They probably are carefully monitoring the heat levels in both the connector plug and the inlet, and throttle it if it gets too hot. Obviously as wear occurs on the connectors this heat rise will only increase, so it would be silly and dangerous to not have good monitoring.
After seeing thermographs of the SC connector plug and vehicle inlet, I can only conclude that pushing 330A through there is probably producing so much heat, that is likely the limiting factor. They probably are carefully monitoring the heat levels in both the connector plug and the inlet, and throttle it if it gets too hot. Obviously as wear occurs on the connectors this heat rise will only increase, so it would be silly and dangerous to not have good monitoring.
Cottonwood
Roadster#433, Model S#S37
The Supercharger Cabinets being shipped today can put out a total of 135 kW DC, but are limited to a max of 120 kW to each port. The 135 kW DC output can only happen charging two cars.
The AC to DC efficiency is about 90%, so the Supercharger Cabinet will take in a max of about 150 kW AC (135kW/90%=150kW). With a max input current of 192 Amps, the Supercharger needs at least 451 Volts to produce the full power out; below that input Voltage, the output power is reduced. That means a nominal input supply of 480 Volts allows for droop in the input Voltage while maintaining full output power.
The 330 Amp max DC Current to each port limits max power to an 85 to 120 kW and to a 40, 60, or 70 to 105 kW because of battery Voltage. The battery Voltage at low SoC is about 360 Volts on an 85 and about 315 Volts on a 40, 60, or 105.
Hmm, I suppose it could be. My original thinking was because of the labels on each module which state 40A max input. But since the internal fuses on the modules are 50A, so we know it could be up to that. So if they are to put out 135kW, that would mean they'd need to pull about 45A @ 277V each. I guess the supporting evidence is the main label which claims the max is 192A @ 480V 3-Phase. This means each unit would be pulling 48A. All this assumes a unity power factor, but supposedly they are all >.99, so close enough.
The module label also claims max output is 30A, with a total on the main label of 330A, that means output max per module of 27.5A, so that works out, although 27.5A would only be 132kW if assuming a Vbatt of 400v (which is well into the taper, so not going to happen on one car). I wonder how granular the outputs can be switched? Do they have relays on each module that can select A or B output? That would mean 8.3% increments are the max granularity. I suppose for full fault tolerance down to the module level, they must have 2 contactors on each module, one to select output channel A and one to select B, and if a module fails, it's contactors can remain off.
So I guess the main question is to run an experiment with 2 cars charging on one cabinet and see what the power split works out to be. Definitely interesting implementation!
Discussed this subjekt with some people from Tesla in Motion.
Compeated cold vs warm weather driving.
You gain around 5-7% in range in warm vs cold weather, and loose around 5% charging time because heat. The car do not manage to keep the battery cold enouch and reduces charge current.
Have you compared charging current and tapper in cold vs hot temperature?
Compeated cold vs warm weather driving.
You gain around 5-7% in range in warm vs cold weather, and loose around 5% charging time because heat. The car do not manage to keep the battery cold enouch and reduces charge current.
Have you compared charging current and tapper in cold vs hot temperature?
The Manual said:
So range mode supposedly limits power not only to the HVAC in the cabin, but also to the battery thermal management system. Has anyone documented the effect of a SC session from a low SOC with and without range mode enabled?
Each charger module in the EU cars and second-generation superchargers consists of 3 sub-chargers, 1 per phase, each capable of doing 16A. Superchargers don't use the L-L voltage, instead they use L-N voltage on a wye 3-phase configuration. Sub-chargers share a common neutral and receive one line conductor from a phase. So each charger module, at nominal power, is 277V * 16A * 3 sub-chargers. I don't think we know the balancing algorithm, or how the load is distributed across modules, but in the wild we know that for full power, step up to the full 277V is desirable (or they would simply use 230V transformers outside the US).
The label you showed was from a first-generation charger module which is a single-phase module @ 40A. These were used in the first-gen superchargers and in US cars.
Last edited:
I can't say either way because I haven't looked inside one of the units. The way that Tesla places restrictions on the chargers in the Norway isolated grid (the 16A single-phase limit) would point to more of a segmentation of the phases than just a bridge. Either way, it doesn't matter - we do know that the gen2 superchargers use the L-N voltage and that the total input of each charging module used is limited to 48A; they require neutral.
Similar threads
