what is the voltage system for the Rivian compared to Tesla?

ajdelange

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Tesla does "advertise" fast charging capabilities and "range" to enhance sales and image.
Of course they do. When Tesla started selling cars the oil interests launched a big campaign to try to suppress sales. Range anxiety, charging time, lack of charging infrastructure, cost and safety (battery fires) were the subjects of much of the disinformation they spread. While most of the "FUD" has been forgotten at this point some of it is still around. And FUD or no there are situations where people don't want to spend more than a couple of minutes refueling their vehicles. The average Super Charger visit seems to be 20 - 30 minutes. Getting that down to 10 - 20 minutes would clearly be to any BEV maker's advantage and 5 - 10 would be even better. This can be done but there are engineering challenges as mundane as the size of the conductors required in the charging cable and as subtle as the effects of high charging rates on battery longevity, The manufacturer has to decide where he wants to be in this trade space.

I have read of owners having their SC experience throttled.
Yes, they have. I even got a warning on the screen (2018 X) to the effect that I had charged to 90% (L 2) several times in a row and advising me that if I didn't tone it down the car would,

I am aware that they reduced the L2 capacity to 11.3kW(is that the number a 60 amp, 240V line can create?) from some higher number.
Tesla used to sell EVSE which could be connected to circuits up to 100 A. EVSE must be derated to 80% of circuit capacity so that meant maximum charging at 80 A and some old Model S could accept charge at that rate. Newer TESLA EVSE (and it seems that of other manufacturers too) is limited to 60 A circuits, Derated that's 48 A which gives the 11.52 kW number which is the number Rivian publishes.


I'm not positive that I am reading significant degradation of their battery packs (-20%) over time but where is the data for this?
Within the fleet. The car calculates its estimated full charge range at the end of each charge. This information is made available through the API. We do not know for certain that Rivian will do the same but assume they will. There are a couple of third party applications that collect this data from your car and others in the fleet. This data gets published from time to time in various places resulting in plots like the one at https://www.teslarati.com/tesla-bat.../tesla-battery-degradation-data-points-chart/.

At least 2 applications I know of will plot the data for your car and one also plots the 'fleet' data for your model with the caveat being that the 'fleet' is others who own your model and subscribe to this app's service.

Untitled 3.jpeg


Note that in this case the 'fleet' is only 19 other cars.
 

Hmp10

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I'm not positive that I am reading significant degradation of their battery packs (-20%) over time but where is the data for this?
The 20% you're remembering probably relates to warranty issues. The Tesla battery warranty is triggered if the battery charge capacity drops more than 20% during the 8-year warranty period. The warranty has only a time limit, not a mileage limit -- meaning that it is not limited by the number of charging cycles.

I have read that as fleet data has accumulated, most EV manufacturers are finding that battery life is longer than anticipated. One study (and I don't remember what generations of the cars were included) showed that Tesla packs experienced a decline of charge capacity of about 6% within a couple of years, but the rate of decline slowed considerably beyond that.

I don't think there's any way Tesla would set the trigger for warranty replacement at 80% if they anticipated packs losing anywhere near 20% of charge capacity over 8 years. I almost always charge my 2015 Model S at home and have my charge limit set at 80%. The range indicated for that limit has only dropped a few miles since I've owned the car. Assuming there is not something dodgy going on in the calculation, that would seem to indicate the battery pack is still taking a pretty good portion of its original capacity.

(For what it's worth, I had to have a battery replacement in my 2015 Model S P85D about three years in. A weld joint failed somewhere between the battery pack and the rear drive unit, and both had to be replaced. Oddly enough, the car began sending me dire warnings of imminent failure, but the car never became undriveable. I was upgraded to a 90-kWh pack, and the car was rebadged as a P90D. I also got a later-generation rear drive unit.)
 

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Yes, I can see how that might be. The statement is true. At double the voltage half the current is required to deliver the same charge rate (with the heat reduction) but a 350 kW charger delivers 350 kWh in an hour whether it delivers it at 437.5 A (800 V) or 875 A (400 V). Perhaps it is because people are less likely to want to build a 350 kWh charger with 800 V architecture than 400.
I have actually looked at the nameplates on the EA 350KW chargers and the ratings for maximum voltage and current are this:

Max voltage = 900V
Max current = 500A

You cannot get 350KW charging even from these stations at 400V. Maximum charging at 400V will be 200KW.

At 900 Volts, to get 350 KW, requires 389 Amps.

At 800 Volts, to get 350 KW, requires 437.5 Amps.

The lowest voltage that can actually get 350KW (500 Amps) is 700V.

The car controls the voltage and current allowed by the charger, thus my Bolt can charge on one of these at 56-57KW peak. Nominal battery voltage on the Bolt or Leaf is 360V, with fully charged being 400V. The Bolt requests up to 160 Amps from the charger at 360V nominal.
 

ajdelange

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I'm not sure where you are going with this but tracing back through the thread I think the claim was made that a higher voltage charger would charge faster and I said BS, that a 350 kW charger delivers 350 kWh in an hr whether the voltage is 800, 400 or 10 but it was then pointed out that there are no 350 kW hr chargers that operate at 400 V. Given that it is apparent that a 800 V charger would be faster and that's where I think it got left.

Your original question was as to whether the Rivian vehicles will take advantage of their patent and charge at 800V. Of course I don't know but using what you just learned the current required to charge the packs in series at 350 kW is below the capability limit of the EA chargers (500A) so 350 kW charging is possible. With the 500A limit at 400 V they can only support 200 kW. Thus charging time if they use the patent would be 200/350 = 4/7 = 57.1% of what they are at 400V. That's certainly worth having. Average DC charging time for a Tesla with a 100 kWh battery generally runs about half an hour to 40 minutes. With the Rivian's 180 kWh battery and potentially greater consumption (relative to Tesla's current heaviest vehicle) that's going to go up to closer to an hour and 800 V charging would get you back to the half hour to 40 minute range. So I guess my best answer to your question is "I hope so". My reasons for fearing that they may not is that 800 V is higher than 400 and thus there are considerations with respect to insulation, PIV ratings of semiconductors (I assume the series/parallel switching is to be done with solid state devices), etc. But they announced that patent application some time ago and the trucks aren't rolling out yet. If the people that supply EA can get these components presumably Rivian can too.

Note that the Tesla 250 kW Super Chargers are 400 V and are thus capable of 625 A.
 
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Hmp10

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Off topic, but Electrify America warns customers that even though charging slows as the battery fills, the cost-per-minute of using the charger remains the same.

Here's the warning: on the EA website:

"We automatically put you into the highest power level available at the charger that is compatible with your car’s charging capability. This is to ensure you get the fastest charge possible . . . . However, once you’re placed into a power level at the beginning of your session, the per-minute price will stay the same throughout the session."

In other words, if you want (or need) a full charge, besides the lengthening time per kWh, you're going to be paying a lot more money for the last 20% of charge than for the first 20%.
 

jjwolf120

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Which is why they should be charging per Kwh, not per minute. Which is why California passed this:

"On December 16, 2019, California’s Office of Administrative Law approved amendments to its Electric Vehicle Fueling Systems Specifications. These rules ban operators of electric vehicle charging stations from billing by the minute at new 240Vac stations in 2021 onwards, and new DCFC stations 2023 onwards."

Also, this is why I want Rivian to have a charging network of their own.
 

DucRider

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Off topic, but Electrify America warns customers that even though charging slows as the battery fills, the cost-per-minute of using the charger remains the same.

Here's the warning: on the EA website:

"We automatically put you into the highest power level available at the charger that is compatible with your car’s charging capability. This is to ensure you get the fastest charge possible . . . . However, once you’re placed into a power level at the beginning of your session, the per-minute price will stay the same throughout the session."

In other words, if you want (or need) a full charge, besides the lengthening time per kWh, you're going to be paying a lot more money for the last 20% of charge than for the first 20%.
EA is shifting to a per kWh model where they are allowed to. Primarily driven by new CA rules that require it.
These rules essentially mandate that electricity be treated like any other fuel, with a display that shows the EVSE’s kWh capacity, price per kWh, and a running meter of kWh delivered. Much like gas/diesel pumps already do.
 

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Note that the Tesla 250 kW Super Chargers are 400 V and are thus capable of 625 A.
I know that Tesla uses a proprietary connector, and that must be rated higher than for CCS. Every spec I have looked at so far for CCS connectors is 500A and 1000V maximums. Also for the CCS standard, liquid cooling is absolutely required for any power above 200KW. The cables and the connector have the liquid cooling, and this is why the EA charging cables are so heavy and stiff, and also are pretty short in length. Without the liquid cooling the wire size would be unmanageable.
 

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Assuming the R1T/R1S can charge at 200kW or more, I'm selfishly okay with per-minute charges. It sucks for Nissan Leaf and Chevy Bolt owners that can't charge at fast rates, but that's a great disincentive to not have a vehicle taking up a spot and trickle charging for long periods of time. If gas stations charged by the minute while you were in a spot, you wouldn't see nearly as many people leaving their cars in the way while they got themselves a drink, went to the washroom, etc...
 

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"On December 16, 2019, California’s Office of Administrative Law approved amendments to its Electric Vehicle Fueling Systems Specifications. These rules ban operators of electric vehicle charging stations from billing by the minute at new 240Vac stations in 2021 onwards, and new DCFC stations 2023 onwards."
I wonder why the long delay in making these regs effective? I assume it would require no equipment modification, but just software reprogramming?

I can see the point, though, in EA's approach, as it would discourage people from spending long times at charging stations for the last few miles of range, thereby speeding up turnover when other cars are waiting.
 

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I wonder why the long delay in making these regs effective? I assume it would require no equipment modification, but just software reprogramming?

I can see the point, though, in EA's approach, as it would discourage people from spending long times at charging stations for the last few miles of range, thereby speeding up turnover when other cars are waiting.
In a lot of places the resale of electrical power comes with limitations that were imposed on the producer because they're a utility, including resale not allowed, so some EV charging stations have even tried pricing the parking space and giving the power away. Every single contract is different and has required changes in legislation/regulation in some places.
 
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