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SeaGeo

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This is the biggest factor and limitation with a 400V-450V architecture.

Electrify America, the largest 350kW charging network in the US is limited to 500amps. With a 400V battery, the max charging rate is 200kW. This is why companies like Porsche and Lucid are using 800/900V packs which allow for a higher charging speed (270kW+) while drawing less than 500amps (the limit of the charger).

So even if the R1T/R1S can handle a higher charging speed, the chargers themselves might be the limiting factor. Which is a bummer. A 200kW limit with a 135kWh+ pack is relatively slow compared to some of the other modern EVs. That's 0-50% in 20 minutes under perfect condition with no charging losses, and maintaining 200kW for the entire 20 minutes. Again that's not bad, but we have cars like the Taycan, Ioniq 5, and Lucid going from 0-80% in about the same amount of time.
Welcome to the "we would like more than 200kw in a premium 2022 vehicle please" club.

Do you know where the patent for this is published? It sounds like the difference between wiring 2 1.5v batteries in parallel to double the amperage vs in series to double the voltage to 3v. Obviously this battery pack has hundreds of tiny batteries so I am wondering if there is some trickery in the HW that can change the power flow dynamically
There's a patent or IP thread floating around here that you should be able to find pretty easily. He's been storing most of their patent applications in one thread.

That being said, I think K and I think it's prudent to assume Rivian isn't using it with the first R1 vehicles. Hence my post pointing out the max charging rate listed in the EPA docs. Rivian has been very inconsistent in the messaging, but all of the formal documentation (s-1 and EPA) says the current vehicles are limited to about 200kw.
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Looks as if it's time to review the charging situation too. The big gun chargers out there now are CHarIn HPC350 class. A charger in that class must support the envelope shown in the picture below. A compatible vehicle commands the charger to whatever voltage it (the vehicle) wants and in so doing controls the current it draws. The Rivian battery is nominally 385 V. Assuming its impedance to be 0.02 Ω were it to draw the maximum an HPC350 can supply, 500 A, the terminal voltage would be 385 + 0.02*500 = 395 V and the charger would be supplying 395*500 = 197.5 kW with the battery getting 385*500 = 192.5 kW. That's 1.42C in a Large which is OK for the early (low SoC) parts if a charge but the truck will certainly pull back as SoC increases. Now it's only 1.07C for a Max and we'd probably want to go faster than that if possible but 500 A is the limit for an HPC350 charger.

Rivian R1T R1S R1T / R1S EPA Test Documentation Confirms Some Details: 210 kW peak DC charging, no heat pump CharIn HPC350

Rivian has filed for a patent (I have not ever seen confirmation that this patent was granted but that doesn't mean it hasn't been) that would split the pack into two equal halves for a nominal voltage of 385*2 =770 V. Reasonable battery impedance implies another load line with shallow slope that would not, as in the 385 V case, terminate on the current limit line but on the power limit line which means that an HPC350 charger could charge the MAX R1T at the full 350 kW. This would be at a rate of 350/180 = 1.94C which is pretty fast even for the bottom part of the SOC range and Rivian has indicated that they will not charge this fast at least early on. Using the 1.42C number from the Large above we'd have 1.42*180 = 256 kW and perhaps that's where the MAX will charge (if the split battery strategy is used).

With the 385V configuration we aren't going to get more than the 190 kW,
 
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Yes, but they do work. While a COP of 4 may be attainable at 45 °F COPs of 2 or so can be realized down to below freezing. Remember that the theoretical COP for a 20 °C cabin with a - 10 °C ambient is 9.76. True, for a +10 ambient the theoretical COP is 29.3.
Yes that’s possible. COP near 2 on modern efficient air source heat pumps at around 30°F and drops to around 1 at around 15 °F on most modern air source heat pumps.

Your theoretical values are just that….theoretical. Heat exchanger size correlates with efficiency and cars have packaging size limitations.

That said, it is generally more efficient than PTC and resistive heating in mild weather.
 
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Looks as if it's time to review the charging situation too. The big gun chargers out there now are CHarIn HPC350 class. A charger in that class must support the envelope shown in the picture below. A compatible vehicle commands the charger to whatever voltage it (the vehicle) wants and in so doing controls the current it draws. The Rivian battery is nominally 385 V. Assuming its impedance to be 0.02 Ω were it to draw the maximum an HPC350 can supply, 500 A, the terminal voltage would be 385 + 0.02*500 = 395 V and the charger would be supplying 395*500 = 197.5 kW with the battery getting 385*500 = 192.5 kW. That's 1.42C in a Large which is OK for the early (low SoC) parts if a charge but the truck will certainly pull back as SoC increases. Now it's only 1.07C for a Max and we'd probably want to go faster than that if possible but 500 A is the limit for an HPC350 charger.

CharIn HPC350.jpeg

Rivian has filed for a patent (I have not ever seen confirmatiob that this patent was granted but that doesn't mean it hasn't been) that would split the pack into two equal halves for a nominal voltage of 385*2 =770 V. Reasonable battery impedance implies another load line with shallow slope that would not, as in the 385 V case, terminate on the current limit line but on the power limit line which means that an HPC350 charger could charge the MAX R1T at the full 350 kW. This would be at a rate of 350/180 = 1.94C which is pretty fast even for the bottom part of the SOC range and Rivian has indicated that they will not charge this fast at least early on. Using the 1.42C number from the Large above we'd have 1.42*180 = 256 kW and perhaps that's where the MAX will charge (if the split battery strategy is used).

With the 385V configuration we aren't going to get more than the 190 kW,
I think you may have their voltage a smidge low based on the EPA docs (hence the 210kw max), but thanks for sharing with folks again.

And agreed. They've communicated to journalists 240kw, and 300+kW. I think the latter was miscommunication, but I can't explain where the hell the 240kw came from. My working assumption is they don't have the split enabled, and/or they're being quiet about it on the max pack to not cannibalize Large pack orders. We will see, but the prudent assumption is ~200kw max for this generation of vehicles.
 

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I work for FAANG too. We don’t design complexity into products if it isn’t adding broad value.
LOLOLOL. Holy shit. If you work for a FAANG, younshould know that needless complexity is like a FAANG forte! We currently have 200 SWEs making a needless dashboard that the Product Divisions have already stated they don’t want. That’s 200 swes that make 300k-600k TC each spending over a year doing random bullshit.
 

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Don't think it'd sell in the Nordics as well as it does if it was designed to work in TX and CA.

You can say a lot of bad things about Tesla and it's CEO that are accurate but to think they only test their vehicles in those two states or design for those two is laughable, especially since they've not made anything in TX and everything we're seeing today is easily a year old design done in CA.

Their cars would be failing everywhere if that were the case.
For what it's worth, there was definitely frustration with the heat pump performance, at least initially, in cold climates. VW ran into the same issue with the ID.4. It can be overcome with some tricks, but in very cold weather they're just not nearly as advantageous as they are above 40ish degrees.
 

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I think you may have their voltage a smidge low based on the EPA docs (hence the 210kw max),
Could well be. The important points are that a battery load line that starts somewhere around 400 V and has a shallow slope terminates on the current limit line whereas one with similar slope that starts around 800 V terminates on the power limit hyperbola.
 
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Could well be. The important points are that a battery load line that starts somewhere around 400 V and has a shallow slope terminates on the current limit line whereas one with similar slope that starts around 800 V terminates on the power limit hyperbola.
Yep! And at 800v with a 350kw cap, thst 140 miles in 20 minutes turns into about 230 miles in 20 minutes.

Also worth reminding folks that the RAN specs are also limited to amps.
 

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LOLOLOL. Holy shit. If you work for a FAANG, younshould know that needless complexity is like a FAANG forte! We currently have 200 SWEs making a needless dashboard that the Product Divisions have already stated they don’t want. That’s 200 swes that make 300k-600k TC each spending over a year doing random bullshit.
That’s the dichotomy of internal vs external customers. Our internal dev is a total shitshow, but our consumer-facing products are focused on mass appeal.

If Tesla’s heat pump wasn’t serving customers outside of California or Texas their cars wouldn’t be selling.
 

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That’s the dichotomy of internal vs external customers. Our internal dev is a total shitshow, but our consumer-facing products are focused on mass appeal.

If Tesla’s heat pump wasn’t serving customers outside of California or Texas their cars wouldn’t be selling.
Then you obviously don’t work for my company. We still pull this shit with external consumer facing products. Yet we’re still worth trillions in market cap.

We have multiple multi-billion (2b plus ) user products that are famously overly complicated.

I work with multiple ex-Tesla folks, one we even just hired from there this month on my team. They say it’s a development shitshow there too.
 

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Then you obviously don’t work for my company. We still pull this shit with external consumer facing products. Yet we’re still worth trillions in market cap.

We have multiple multi-billion (2b plus ) user products that are famously overly complicated.

I work with multiple ex-Tesla folks, one we even just hired from there this month on my team. They say it’s a development shitshow there too.
I’m sure it is a mess, but the point still remains: if the heat pump didn’t work in cold climates Tesla wouldn’t be selling cars.
 

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I’m sure it is a mess, but the point still remains: if the heat pump didn’t work in cold climates Tesla wouldn’t be selling cars.
And “Works” is very different than working well.
 

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Tesla is absolutely a California-centric company. Living in a colder climate makes it quite clear they just do not spend anything but the bare minimum of effort for non-moderate climates. There are software improvements that they could make that would definitely make living with my Model 3 in winter easier. Yet ... nothing.

They sell everything they make, so ultimately, good for them. Hell I bought one too. But I will be moving on once a remotely reasonable alternative is available. My R1S can't arrive soon enough.

To why not heat pump in the R1's? I imagine it was a complexity trade off. The first year of Tesla heat pump enabled cars had a rash of issues. A +1 for California company or shoddy testing? Why not both? But ultimately I don't fault Rivian for the decision. An issue like this one for a first gen product that is billed as an "adventure vehicle" risking not having heat? That would be extremely damaging to a new company/brand. Much safer to utilize tried and true "toaster tech" and take the efficiency hit.

https://electrek.co/2021/01/01/tesla-model-3-y-cars-plagued-heating-issues/
https://teslamotorsclub.com/tmc/threads/2021-model-3-y-heating-issues.221095/
 

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Really curious about the lack of heat pump as well. Tesla went all-in on the heat pump for efficiency. Aside from the obvious “cost savings” excuse why would they forgo a heat pump?
I don't understand how it can be that much more expensive than plain A/C. It is just running the A/C backwards, for all practical purposes.
And if it can't keep up in super cold weather, then just put a heating element in series to pick up the slack.
 

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Don't know a damn thing about Heat Pumps. Wonder if part of the rationale is simply about reliability.... just another thing that isn't there to go wrong :)
Heat pumps are A/C units that can run both directions. Pushing heat inside to the outside in the summer, and pushing heat from the outside to the inside in winter.
It shouldn't be that much less reliable than plain A/C.
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