azbill

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Well that 100% depends if it has a buffer like Taycan or not, and the charging curve. If R1T is 300 miles at using 100% of battery then you're wrong, if its 90% of battery, it's pretty close but again would depend on the curve(at 900v)
Has little to do with a "buffer", which might represent 5% of the battery capacity. The Taycan has 80KwH usable and thus charging at 270KW is 3.4C rating. C rating is charge rate / battery capacity. At 200KW charge rate the Rivian battery is at 1.5 C, at 300 KW it will be at 2.2C, still less than the Taycan. Taycan starts to taper at 25% SoC because of that high charge rate.

A Max Pack at 300KW would be charging at 1.7C.

As a reference point the Audi E-Tron charges at 1.8C all the way from 0% to 70% before it tapers.





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mkennedy1996

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Well that 100% depends if it has a buffer like Taycan or not, and the charging curve. If R1T is 300 miles at using 100% of battery then you're wrong, if its 90% of battery, it's pretty close but again would depend on the curve(at 900v)
Here is my understanding. The Taycan has a 79kw battery pack and the R1S has a 135kw pack. (The Taycan is including the buffer and I assume the R1S is as well). The R1S has a 71% larger battery. The Taycan charges in the 20 to 80% window at an average of 224kw (see below). So the R1S can be charged at an average of 383kw over that same range with the exact same amount of power being applied to each cell of the battery as the Taycan at only 224kw. This is because the charge energy is distributed over the size (total kw capacity) of the battery.

We are talking about the fast charging impact upon battery health and not the actual charging curve of the R1S, since that is unknown at this point. The larger the battery, the more energy you apply to the total pack without increasing the energy to any one cell.
p3-charging-index-2019-02-min-888x444.png
 
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CommodoreAmiga

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So the R1S can be charged at an average of 316kw over that same range with the exact same amount of power being applied to each cell of the battery as the Taycan at only 224kw. This is because the charge energy is distributed over the size (total kw capacity) of the battery.
In theory, that would mean the ~180kWh pack could sustain a higher average charge rate than the 135kWh pack, right?
 

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Has little to do with a "buffer", which might represent 5% of the battery capacity. The Taycan has 80KwH usable and thus charging at 270KW is 3.4C rating. C rating is charge rate / battery capacity. At 200KW charge rate the Rivian battery is at 1.5 C, at 300 KW it will be at 2.2C, still less than the Taycan. Taycan starts to taper at 25% SoC because of that high charge rate.

A Max Pack at 300KW would be charging at 1.7C.

As a reference point the Audi E-Tron charges at 1.8C all the way from 0% to 70% before it tapers.
Why do you use full capacity for Rivian and not for Taycan? Taycan has a 93.7 kwh battery but electronic buffer(limiting use) to 83, you calculate c rating on full capacity, not some arbitrary safety.
 

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mkennedy1996

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In theory, that would mean the ~180kWh pack could sustain a higher average charge rate than the 135kWh pack, right?
Yes and less stress on the battery. I think that is why Ducrider mentioned the 180 pack may be worth waiting for.
 

mkennedy1996

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Why do you use full capacity for Rivian and not for Taycan? Taycan has a 93.7 kwh battery but elecvtronic buffer(limiting use) to 83, you calculate c rating on full capacity, not some arbitrary safety.
I used the regular Taycan that I found specs for 71 usable and 79 total capacity
 

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And yes, I wasn't saying 300kwh was bad for Rivian, I was saying it's necessary. If you somehow went to 0-100 at 300kwh(Which you won't ) still 30 mins to full, which is good I admit, but that isn't happening. 200 is 45, which, still isn't happening. When my Model x would road trip, even at 200kw max rate at v3 sc, it was pretty painful to wait vs model 3 due to curve and battery capacity. Maybe people are ok waiting over an hour for full charge if it's only for a last stop before adventure but charging to me is more important than range.

Cause 200kwh average rate in a Taycan is 28 mins to full, 300 average in a 130kwh rivian is 29.
 

mkennedy1996

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Why do you use full capacity for Rivian and not for Taycan? Taycan has a 93.7 kwh battery but electronic buffer(limiting use) to 83, you calculate c rating on full capacity, not some arbitrary safety.
Redoing the calcs for the larger Taycan battery, yields similar results:

The Taycan has a 93.4kw battery pack and the R1S has a 135kw pack. (The Taycan is including the buffer and I assume the R1S is as well). The R1S has a 45% larger battery. The Taycan charges in the 20 to 80% window at an average of 224kw (see below). So the R1S can be charged at an average of 324kw over that same range with the exact same amount of power being applied to each cell of the battery as the Taycan at only 224kw. This is because the charge energy is distributed over the size (total kw capacity) of the battery.
 

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Redoing the calcs for the larger Taycan battery, yields similar results:

The Taycan has a 93.4kw battery pack and the R1S has a 135kw pack. (The Taycan is including the buffer and I assume the R1S is as well). The R1S has a 45% larger battery. The Taycan charges in the 20 to 80% window at an average of 224kw (see below). So the R1S can be charged at an average of 324kw over that same range with the exact same amount of power being applied to each cell of the battery as the Taycan at only 224kw. This is because the charge energy is distributed over the size (total kw capacity) of the battery.
Yeah again, not sure why you're arguing that. I simply said that I'd rather have 300kw charging and good battery life because it's possible, look at Taycan. It's new but got the buffer for the slight degradation and Porsche feels pretty confident or they wouldn't put it out. (additionally, the Rivian *can't* charge at the same respective rates(324kw), so 300 should be seen as the standard.)
 

mkennedy1996

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And yes, I wasn't saying 300kwh was bad for Rivian, I was saying it's necessary. If you somehow went to 0-100 at 300kwh(Which you won't ) still 30 mins to full, which is good I admit, but that isn't happening. 200 is 45, which, still isn't happening. When my Model x would road trip, even at 200kw max rate at v3 sc, it was pretty painful to wait vs model 3 due to curve and battery capacity. Maybe people are ok waiting over an hour for full charge if it's only for a last stop before adventure but charging to me is more important than range.

Cause 200kwh average rate in a Taycan is 28 mins to full, 300 average in a 130kwh rivian is 29.
I have only owned Teslas since 2015. The charging curve for a Tesla is very bad. They quote a large number, but it does not maintain that high level and drops rapidly. I believe Tesla is the exception. The Rivian is quoting an average of 180.6kw for 20 minutes to add 140 miles of range. That would put it way way way above the sustained Tesla levels.

You mention "until full" in your post. I have supercharged over 400 times and can count on 1 hand how many times I have supercharged above 90%. Your goal when road tripping should be to arrive with about 15-20% SOC and only charge enough to get to your next charger (with your comfort zone buffer added in). Anymore than that, and you end up spending more time charging than needed. (and with chargers that charge by the minute rather than kw - you end up wasting money as well). Note: All of the BEVs have terrible charge rates above 80% (even the Taycan) compared to the 20 -80% "sweet spot" range.
 

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I have only owned Teslas since 2015. The charging curve for a Tesla is very bad. They quote a large number, but it does not maintain that high level and drops rapidly. I believe Tesla is the exception. The Rivian is quoting an average of 180.6kw for 20 minutes to add 140 miles of range. That would put it way way way above the sustained Tesla levels.

You mention "until full" in your post. I have supercharged over 400 times and can count on 1 hand how many times I have supercharged above 90%. Your goal when road tripping should be to arrive with about 15-20% SOC and only charge enough to get to your next charger (with your comfort zone buffer added in). Anymore than that, and you end up spending more time charging than needed. (and with chargers that charge by the minute rather than kw - you end up wasting money as well). Note: All of the BEVs have terrible charge rates above 80% (even the Taycan) compared to the 20 -80% "sweet spot" range.
Yeah quite familiar with charging practices. But for Rivian I'm wondering if 140 in 20 mins is 400 pack or 300. Also we don't know how accurate 300 is, at like 70mph. Tesla is also bad at that. They get far under EPA at 70mph where Taycan gets far over. Which is another reason I gave Taycan as a good example Good charging, good actual range at hwy speeds, little to no degradation.
 

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This will be my first electric vehicle so pardon my ignorance/confusion but question for you guys... I was looking at the Chargepoint Flex vs the Rivian charger and charge point offers it as low as 16 AMP all the way up to 50 amps. What is the Rivian supposed to be and can a common electrical panel even support something as high as 50?
 

mkennedy1996

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Yeah quite familiar with charging practices. But for Rivian I'm wondering if 140 in 20 mins is 400 pack or 300. Also we don't know how accurate 300 is, at like 70mph. Tesla is also bad at that. They get far under EPA at 70mph where Taycan gets far over. Which is another reason I gave Taycan as a good example Good charging, good actual range at hwy speeds, little to no degradation.
I have to ask. You seem to be pretty enamored with the Taycan. Why aren't you buying one of those?
 

mkennedy1996

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This will be my first electric vehicle so pardon my ignorance/confusion but question for you guys... I was looking at the Chargepoint Flex vs the Rivian charger and charge point offers it as low as 16 AMP all the way up to 50 amps. What is the Rivian supposed to be and can a common electrical panel even support something as high as 50?
For most homes built in the last 20 or so years. I would say yes.

The charger rating has to be 20% less than the breaker than you install it on. So a 48 amp charger would need a 60 amp breaker. This is because the chargers draw a sustained current and code requires that the breaker and wiring be larger to handle that power over long periods of time.

I currently have a 72amp charger on a 100amp breaker and did in my previous house as well. No issues in either case.

I believe the Rivian can handle up to a 48amp charger.
 

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