EA decides to shut down chargers along nearly 500 miles of I-95 over long holiday weekend to perform upgrades

DucRider

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The Rivian is a 400 V truck and the CT will be too.
Do you have a source for either of these?
AFAIK, neither Rivian nor Tesla has announced the voltage architecture on these products. Rivian filed far a patent for series/parallel, but that was quite some time ago and it may or may not be implemented (lots of patents are never brought to market).

800 - 900V has significant advantages in both charging and system architecture. 350 kW at 400V requires a significantly beefier cable than one at double the voltage. Internal wiring on the vehicle also can be smaller/lighter/cheaper. Same goes for motors - higher voltages have advantages in winding wires size, weight, cost, etc. (look at Lucid as an example).

Every EA location I have seen or pulled up on Plugshare has both 350 and 150 kW chargers, but it is possible a few may have only 150kW.

Note that times for either option will be longer than that because of taper. I thought it interesting the amount of emphasis RJ put on that aspect of it in the video interview.
Yes, RJ is ultra conservative in his promises and having it clear that 300 kW is dependent on SOC is a detail most companies gloss over. Tesla, for example, touts the Model 3 LR can charge at 250 kW, but that only occurs at a SOC of between about 10 - 16%. After that the taper kicks in pretty significantly.
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We don't yet know any real charging specs on the Rivian, but RJ has stated that the battery will be "smart" an adjust to charging and usage patterns of individual owners. I'm very interested to find out what parameters change.
 

ajdelange

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Do you have a source for either of these?
Alas, we must rely on what we do know and that very uncommon thing we used to call common sense. Tesla has always built 400V cars. It's latest motors are 400 V. The Semi uses 400V motors, their huge supercharging infrastructure is 400 V, their batteries are 400V. They have given no hint anywhere that they are considering 800 V but you can bet your bottom dollar that they are. Eventually they will migrate to 800 V architecture but not on this round of vehicles. Perhaps they will surprise us in the new Roadster.

Much less is known about Rivian. We can't look in one and see that it has a 400V battery as we can with a Tesla. Sandy Munroe hasn't torn one of their motors down but with Rivian we can ask ourselves "Why would they file a patent for a scheme that splits a battery pack into 2 for charging from an 800 V source which patent clearly shows how to keep the vehicle's 400 V system alive if they don't plan to use it on a 400 V vehicle?" Now it's possible that they have secretly developed an 800 V system (battery, motors, inverters) and only filed the patent in order to block Tesla from using this scheme. Personally I find the liklihood of that to be vanishingly small so, if it makes you happy, I will rephrase the statement to "In all liklihood the Rivian will be a 400 V architecture and in all liklihood Tesla will stay with a 400 V system for the near term."


Rivian filed far a patent for series/parallel, but that was quite some time ago and it may or may not be implemented (lots of patents are never brought to market).
It was files May2 2019. That may seem like an eternity ago in terms of which the state of the art is advancing. You may want to use this to construct a fantasy in which Rivian has changed their architecture to 800 V and indeed there is a finite but tiny chance that they did but a prudent man, i.e. one with a modicum of common sense (and perhaps some engineering knowledge is required too) would conclude that RJ's statement is evidence that the patent is being implemented.

800 - 900V has significant advantages in both charging and system architecture. 350 kW at 400V requires a significantly beefier cable than one at double the voltage.
You seem to be aware that losses (reflected as heating of a conductor) increase rapidly (as the square) of the current so that pushing 600 A through a cable will generate 4 times the heat generated with 300A. This is why the power company transmits at very high voltage over long distances. Most of the wire in a power grid is in the distribution part.

Internal wiring on the vehicle also can be smaller/lighter/cheaper.
If you run 300 A through a wire that is half diameter cross section of another wire which is carrying 600 A the losses are the same in each (current is halved but the resistance per unit length which is porportional to the wire diameter is quadrupled). If you decrease wire diameter by √2 the power loss goes down by 1/2 and you lose some weight. It's a trade space. You can be more efficient but have to keep the weight or lose some weight but have to give up efficiency.


Same goes for motors - higher voltages have advantages in winding wires size, weight, cost, etc. (look at Lucid as an example).
So now it's my turn to ask "Do you have a source for that?" You are evidently not aware that if you halve the current through a motor's windings you must wind twice as many turns in order to obtain the same flux (it is flux that develops torque). So if you decide to reduce wire diameter by √2 (half the area) you will have half the loss per unit length of wire but must have twice as much linear length to produce the same torque. Where's the savings there? In addition higher voltage requires insulation of higher dielectric strength which obviously costs more.

In the inverter higher voltage means semiconductors with higher withstand voltage ratings are required. In the off state the losses in these semiconductors are proportional to the square of the voltage so that for the same off state resistance an 800 V device will produce 4 times the heat. During transition to on state the high voltage device spends more time with high S-D voltage than is the case with the lower voltage architecture. Etc.

In the battery higher voltage means more cells (or groups of cells) in series. That doubles the equalization burden. But it does mean less cell current. Doubling the battery voltage results in a reduction of the heat dissipated in each cell's internal impedance (or the resistive part therof) by a factor of 4. But there are twice as many cells in series so the improvement is half - not a quarter as you might at first think.

Thus high voltage clearly shines where you have to send current some distance. Otherwise the advantages are not so clear.



Tesla, for example, touts the Model 3 LR can charge at 250 kW, but that only occurs at a SOC of between about 10 - 16%. After that the taper kicks in pretty significantly.
Do you have a source for that?

Showing me a single charging history only tells me that somebody under circumstances about which I know nothing charged a 3 at a V3 charger and got 250 kW over that band. What happened to the guy who pulled in behind him? Or the fellow who came in that night. What happens with a Y under various circumstances? You need to understand that it is the car, not the charger that determines the charging profile and what it asks for can depend on various factors. I've looked at enough charging profiles to know that but I certainly haven't the temerity to declare what the charging profile for a particular Tesla vehicle is.



We don't yet know any real charging specs on the Rivian,
Well he did say in the video that it will accept up to 300 kW dependent on SoC and so I don't doubt that it will do that.


...
but RJ has stated that the battery will be "smart" an adjust to charging and usage patterns of individual owners.
It had better be.

I'll note that Apple said in notes that came with the last iPhone I bought that the phone would keep track of my charging habits and automatically keep the battery out of the top 20% to the extent it could. If it is actually doing that there is no evidence of it that I can see.[/QUOTE]
 

DucRider

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RJ in Dec 2018 (LA Auto Show):
“To get to the 300-kw [charging] level that everyone wants to be at—of course us included—voltage levels have to go up to get the current levels down,” said Rivian CEO RJ Scaringe to Green Car Reports, in a long and far-reaching interview last month at the LA Auto Show. “So we’ve architected everything in the system to see higher voltages at the right time and therefore go to much higher levels of charging...but that won’t be at day one.”
The leap to double the voltage can be accomplished, Scaringe outlined, by doubling the S count [the number of cells connected in series] and halving the P count [the number of cells connected in parallel]. “So we go from a peak of 450 volts to 900,” he said.​
Rivian already has that double-voltage, peak 900-volt (nominal about 800V) battery pack in development, and it’s actually designed all the connectors and bus bars for production.​
It’ll be some time before the battery pack goes to 800-volts, however, Scaringe underscores. “The reason for that is the supply base of all the high-voltage ‘stuff’ in the vehicle, the electric compressor, DC-DC converter, is all built up around a sub-450 world,” he said. “As the world builds out 800-volt capability, everything’s architected so very quickly we can switch over to 800 volts."
Stepping up the voltage isn’t a matter of just swapping in a few components here or there. Relatively simple changes that need to be accommodated, such as the placement of connectors and the spacing of leads, need to be planned from the start.​
The industry won’t see a lot of availability of 800-volt components from suppliers until 2021 or 2022, Scaringe estimates​
Power levels go up, charging speeds go up, everything gets better,” added Scaringe, in a much more enthusiastic tone. “As good as the vehicle is today, when we double the voltage it’ll be better.”

In January of 2020, he confirmed that Rivian would be able to charge at 300 kW, while in 2018 he said that would not be the case. While it is possible they did not make the move with the rest of the system components, I think it likely that availability of components advanced faster than he originally anticipated, and there is a good chance we will see an 800V system

https://www.greencarreports.com/new...ready-for-future-800v-upgradepossibly-in-2022
 

ajdelange

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If you can interpret RJs remarks there as implying that the car I hope to see in my driveway will have an 800 V architecture, well, you are a much more imaginative guy than I am.
 

azbill

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GM has announced that the Hummer EV will be 800V and charge at 350KW. But they also stated that all their other EVs in development, including the Cadillac SUV, will be 400V. I seriously doubt that Rivian has changed their design to 800V, in the last two years, that takes a lot of engineering and changes to supply chains. Personally, I do not care which voltage it is at, but I do want the 300KW charging capability at initial delivery, otherwise GM may get my money instead.
 

azbill

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This is, of course, good news but the price is pretty steep.
I just got a bill from EVGO for a charge I did this month, and they are charging 45 cents per KWH, so this is on par with that.
 

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