Rivian Vs Tesla

[ajdelange]

Actually the Model 3 with the latest software update matches the NMC's quite well,
Tesla raises Model 3 charge capacity to 200 kW - electrive.com

it reaches 80kW charging speed on a 80kWh battery at displayed 73% SoC. Real SoC = (4kWh+73%*76kWh)/80kWh = 74%

If you had used this tapering curve, that puts the Rivian to 180kW net charging speed at 74% SoC.

Can't really figure out what you are trying to say here but I did put in the 140 kW charging curve from the link. The ratio, for that taper is 1.21 (Rivian time/Tesla time).

Not sure how profitable continuing to search for ways to prove me wrong is going to be for you. Just remember that whatever you might come up with for Super Chargers that when you are charging at home with a Rivian next to a Tesla the ratio of the kWh consumed to replace 1 mile driven in each is going to be the same as the ratio of the Wh/mi for each and, if you charge the two cars from the same charger at the same rate, the ratio of the required times is going to be that same number.

 

[Feathermerchan]

What people refer to as charge taper is the reduction in current (charge rate) as the battery state of charge increases.
I fly electric model airplanes with Lithium batteries. Our chargers are our BMS and are not in the plane due to weight. We remove the battery and connect it to the charger after each flight. The chargers are all digital now and show each cell voltage. When a cell in the pack reaches 4.2V the charger starts reducing current to prevent the voltage from exceeding 4.2
That can be the start of the 'taper'. As state of charge increases battery voltage increases. Battery Voltage also increases with charge current. So if you charge at a faster rate, taper will have to start sooner (lower SOC). This is assuming the same battery chemistry.
Battery chemistry (even within Lithium Ion) affects how much the battery Voltage rises with charge current and drops with discharge current. We model this using a thing called internal resistance.

 

[T3slaOwner]

What people refer to as charge taper is the reduction in current (charge rate) as the battery state of charge increases.
I fly electric model airplanes with Lithium batteries. Our chargers are our BMS and are not in the plane due to weight. We remove the battery and connect it to the charger after each flight. The chargers are all digital now and show each cell voltage. When a cell in the pack reaches 4.2V the charger starts reducing current to prevent the voltage from exceeding 4.2
That can be the start of the 'taper'. As state of charge increases battery voltage increases. Battery Voltage also increases with charge current. So if you charge at a faster rate, taper will have to start sooner (lower SOC). This is assuming the same battery chemistry.
Battery chemistry (even within Lithium Ion) affects how much the battery Voltage rises with charge current and drops with discharge current. We model this using a thing called internal resistance.

There are other issues than just exceeding a given voltage. When charging a Tesla the graphite anode absorbs lithium into the carbon lattice. This causes the anode to swell. On the low state of charge I don't recall the mechanism, but too high a rate of charge will cause the lithium to plate the anode rather than be absorbed. This problem diminishes as the state of charge rises. Then at higher states of charge the degree of lithium absorption becomes high enough the anode swells and causes damage if too rapid.

These effects are impacted greatly by the details of the construction and composition of the battery. It is likely your model airplane batteries have different issues that lead to charging limitations as well as using simpler controllers with fewer capabilities. Bottom line is what works best for your airplanes may not be what works best for Tesla batteries.

 

[Feathermerchan]

Agreed T3slaOwner.
We can charge up to 5C. That's 5 times the capacity which translates from 20% to 100% in 12 min or less. (I usually charge at 2C).
And the high performance planes limit flying time to 6 min. 100% to 20%
Helicopters more like 4 minutes.
The batteries come down pretty warm but are put right back on the charger and reflown over and over.
With 2 or 3 chargers you never wait for a battery to be finished charging. You can fly continuously all day.
I have batteries that are years old so they last pretty well considering what we do to them.

 

[acoste]

Can't really figure out what you are trying to say here but I did put in the 140 kW charging curve from the link. The ratio, for that taper is 1.21 (Rivian time/Tesla time).

Not sure how profitable continuing to search for ways to prove me wrong is going to be for you. Just remember that whatever you might come up with for Super Chargers that when you are charging at home with a Rivian next to a Tesla the ratio of the kWh consumed to replace 1 mile driven in each is going to be the same as the ratio of the Wh/mi for each and, if you charge the two cars from the same charger at the same rate, the ratio of the required times is going to be that same number.

What I'm saying is that if you used the tapering of this updated Tesla Model 3 for the Rivian, it should have finished in less than an hour. Yet you came up with 77.72 minutes. So your calc is incorrect.

 

[ajdelange]

When I used that taper for the Rivian the time came out to 58.2 minutes. So, according to you, my calculation is correct. As I said many posts ago this isn't rocket science. If you add taper to the problem you have to do a numerical integration over the taper curve but it still isn't rocket science. That's why my calculations are correct for whatever taper I put in. The 77 minute number was for an exponential taper to 20%. More to the point is that you have no idea what the Rivian taper will be.

Try again.

 

[T3slaOwner]

When I used that taper for the Rivian the time came out to 58.2 minutes. So, according to you, my calculation is correct. As I said many posts ago this isn't rocket science. If you add taper to the problem you have to do a numerical integration over the taper curve but it still isn't rocket science. That's why my calculations are correct for whatever taper I put in. The 77 minute number was for an exponential taper to 20%. More to the point is that you have no idea what the Rivian taper will be.

Try again.

Indeed, neither do you... so try again...

 

[acoste]

When I used that taper for the Rivian the time came out to 58.2 minutes. So, according to you, my calculation is correct. As I said many posts ago this isn't rocket science. If you add taper to the problem you have to do a numerical integration over the taper curve but it still isn't rocket science. That's why my calculations are correct for whatever taper I put in. The 77 minute number was for an exponential taper to 20%. More to the point is that you have no idea what the Rivian taper will be.

Try again.

Let me remind you what you wrote:

"Assuming it also arrives at the charger with 10% it would need to be charged to 76.5% of capacity to replace the 119.7 kWh. A 150 kW charger with the same taper would require 77.72 minutes to charge the Rivian. That's a factor of 1.3 times longer. This ratio does not, BTW, depend on the size of the charger but it does depend on the taper curve. I used a linear one for simplicity and another linear of different slope will give a different answer as will ones with different shape. For example, if I use an exponential taper (faster at low SoC) but to the same level at 100% SoC then the ratio increases slightly (1.314)."

"Yes, taper was adjusted to the battery and assumes that Rivian's tapering scheme and Tesla's are the same."

"Can't really figure out what you are trying to say here but I did put in the 140 kW charging curve from the link. The ratio, for that taper is 1.21 (Rivian time/Tesla time)."


Now even the 58.2 minutes is too much if you used the same taper as the updated Model 3 or the Audi from that link. ... "rocket science"

As I mentioned the Rivian (copying the Model 3's taper) can still accept 180kW charge at 74% SoC. So in the calculation above, there shouldn't be any decrease in charge power over time.

This is why I said: "If we use a 150kW charger with 10% efficiency loss, 119.7 kWh / 135kW = 53 min."

 

[ajdelange]

OK. 77.72 min was for a linear taper to 20%. 77.26 minutes is for an exponential taper to 20%. Conclusion? Linear or exponential doesn't make much difference.

I did what I did using a robust algorithm. I've said that the answer you get depends on the profile. So instead of criticizing what I have done based on my not using profiles you like why don't you do some calculations yourself using whatever taper or tapers you think might apply? It really very easy to do. You look at the energy in the battery at the current time and compute SoC from that by dividing by the capacity. Now look up in a table (or have a function compute) the rate allowed at that SoC. Convert that to Wh/sec (= kW/3600) and add the Wh/sec to the energy. Increment time by one second. Repeat until the SoC reaches whatever value you are interested in. This is trivial to program in any language and you can try charge levels and tapers to your hearts content, adjusting parameters until you get the answer you want.

 

[acoste]

OK. 77.72 min was for a linear taper to 20%. 77.26 minutes is for an exponential taper to 20%. Conclusion? Linear or exponential doesn't make much difference.

I did what I did using a robust algorithm. I've said that the answer you get depends on the profile. So instead of criticizing what I have done based on my not using profiles you like why don't you do some calculations yourself using whatever taper or tapers you think might apply? It really very easy to do. You look at the energy in the battery at the current time and compute SoC from that by dividing by the capacity. Now look up in a table (or have a function compute) the rate allowed at that SoC. Convert that to Wh/sec (= kW/3600) and add the Wh/sec to the energy. Increment time by one second. Repeat until the SoC reaches whatever value you are interested in. This is trivial to program in any language and you can try charge levels and tapers to your hearts content, adjusting parameters until you get the answer you want.

I have already calculated it. But you are not paying attention.

"Now look up in a table (or have a function compute) the rate allowed at that SoC."

As I mentioned the Rivian (copying the Model 3's taper) can still accept 180kW charge at 74% SoC.

This means if I charge it from 10% to 76.5% on a 150kW charger, it will never taper. So the equation becomes this easy: 119.7 kWh / 135kW = 53 min

 

[ajdelange]

But if you charge it to 85% it will.

I've shown you how to do these calculations correctly. Just do them for whatever assumptions/conditions you want to make.

I don't particularly need to know what you determine and you/we are focusing too much on this particular aspect of Rivian vs. Tesla. The Rivians use more energy than Teslas. It's going to take more to charge them. It's that simple.

 

[ajdelange]

Personally I pre-ordered Rivian R1S and canceled it after seeing it in NYC auto show.

What did you see, or not see, that made you do that?

Rivian had to cover long way to match with Tesla and it will match at some point, charging is the main issue as Electrify America charge rates at present r very expensive.

No doubt about that. Did you take into consideration that most of the charging will be done at home? It will cost more even there though as the Rivian is, relative to the Tesla a joule guzzler.

Autopilot also had a long way to go as their fleet is yet to start on roads.

I'd say Telsa's autopilot has a long way to go too!

Note that I am not trying to convince you to change your mind. I've got a deposit down on the truck but I have not seen it and am very curious as to what hit you when you did. The other stuff I can live with as a few extra bucks on a few road trips don't bother me and I charge from solar at home. I'm more concerned about the reliability/availabilty of non Tesla chargers than the cost at this point.

 

[Feathermerchan]

I watched a video today by Like Tesla Kim (?) and during an interview with the Rivian CEO, he said they were working on a charging network. Wouldn't say if it was a partnership or their own. An agreement with Tesla to use their Supercharging system would make a huge difference. Especially for an 'adventure' vehicle that is expected to travel not just get groceries.

 

[T3slaOwner]

I watched a video today by Like Tesla Kim (?) and during an interview with the Rivian CEO, he said they were working on a charging network. Wouldn't say if it was a partnership or their own. An agreement with Tesla to use their Supercharging system would make a huge difference. Especially for an 'adventure' vehicle that is expected to travel not just get groceries.

The Tesla network would be the best choice for the short term. I suppose that regardless of the eventual fortunes of the Tesla company, the network will remain. Potentially it will end up in mercurial hands and the costs will rise, but it is very unlikely it will be shut down. Rather like the Iridium network. Even when the company failed with it's intended plan, the satellites were such a significant asset they are being reworked for new uses.

 

[xG35]

Rivian will be an alternative to Tesla offering if they succeed and get off the ground somehow; yet to be seen.

That said, their focus in NA market will limit their potential. If it is not known in China or Asia, it will not fly.

 

[ajdelange]

A bit more info from an e-mail a member in a Rivian forum got from the company:

•Their goal for service is that it will be done at your location or you will be given a loaner and the vehicle trucked away.
•They are working on a charging network
•They will supply equipment for charging at home

They are still playing their hand pretty close to their vest (the second bullet is particularly cryptic) but just the fact that they responded to an e-mail is a sharp uptick in the information they are providing.

In further playing around with ABRP and PlugShare I conclude that as things stand today:
1)Tesla chargers are closer to arteries than non Tesla chargers
2)Tesla chargers are of higher capacity than the preponderance of existing non Tesla chargers
3)Tesla chargers are more reliable than non Tesla chargers.
4)You need to take on more joules per mile driven with a Rivian than with a Tesla
5)Joules are more expensive from non Tesla chargers

Putting 3) aside you are going to spend more time charging the Rivians and/or getting to the charging stations than with a Tesla and you are going to pay more. None of this really worries me. It is actually 3) that concerns me the most. I would, were I able to make a trip in a Rivian today, probably plan to avoid the higher rate CCS chargers today because if you look at what's reported on PlugShare it is not certain that charging will be available when you get to the station. We, of course, assume, hope and feel pretty certain that EA will have ironed out these problems by the time Rivian starts making deliveries but there will always be the trade of getting off the freeway to get to a Walmart to get a 100 kW charge vs staying on the freeway and using an existing 50 kW charger.

Now it is not necessary for anyone to post "Well I just put in a trip from my mother in laws house to my aunt Sophies and found the Rivian required less charging" because I already know that there will be cases like that. It is clear, for example, that if you are comfortable using 75% of the battery capacity on a BEV that you can go 300 miles in a Rivian without charging at all whereas with a pre Raven X you would most likely want to as 300 mi is more than the EPA rating for that vehicle. Thus my findings are what one can expect on longer trips with the charging network as it is today. For the moment, Tesla has the advantage. That may change.

 

[acoste]

A bit more info from an e-mail a member in a Rivian forum got from the company:

•Their goal for service is that it will be done at your location or you will be given a loaner and the vehicle trucked away.
•They are working on a charging network
•They will supply equipment for charging at home

They are still playing their hand pretty close to their vest (the second bullet is particularly cryptic) but just the fact that they responded to an e-mail is a sharp uptick in the information they are providing.

In further playing around with ABRP and PlugShare I conclude that as things stand today:
1)Tesla chargers are closer to arteries than non Tesla chargers
2)Tesla chargers are of higher capacity than the preponderance of existing non Tesla chargers
3)Tesla chargers are more reliable than non Tesla chargers.
4)You need to take on more joules per mile driven with a Rivian than with a Tesla
5)Joules are more expensive from non Tesla chargers

Putting 3) aside you are going to spend more time charging the Rivians and/or getting to the charging stations than with a Tesla and you are going to pay more. None of this really worries me. It is actually 3) that concerns me the most. I would, were I able to make a trip in a Rivian today, probably plan to avoid the higher rate CCS chargers today because if you look at what's reported on PlugShare it is not certain that charging will be available when you get to the station. We, of course, assume, hope and feel pretty certain that EA will have ironed out these problems by the time Rivian starts making deliveries but there will always be the trade of getting off the freeway to get to a Walmart to get a 100 kW charge vs staying on the freeway and using an existing 50 kW charger.

Now it is not necessary for anyone to post "Well I just put in a trip from my mother in laws house to my aunt Sophies and found the Rivian required less charging" because I already know that there will be cases like that. It is clear, for example, that if you are comfortable using 75% of the battery capacity on a BEV that you can go 300 miles in a Rivian without charging at all whereas with a pre Raven X you would most likely want to as 300 mi is more than the EPA rating for that vehicle. Thus my findings are what one can expect on longer trips with the charging network as it is today. For the moment, Tesla has the advantage. That may change.

This is what hardcore Tesla fans call FUD.

Earlier you kept miscalculating charging time favoring Tesla. Then you mistakenly state Rivian takes more time to charge than Tesla despite my inputs. And now this. Congrats.

 

[HostileHarry]

So I played with ABRP a little bit more this morning to test out a trip from my home in IL to Denver International Airport, which is roughly 1000 miles. Here is the breakdown for estimates from ABRP.

Tesla (Total trip time hr/m):
Model X Raven - 16:20 Total trip / 2:50 of that is charging
Model X 100D - 16:57 Total trip / 3:19 of that is charging
Model X 90D - 18:08 Total trip / 4:17 of that is charging

Rivian R1S (the SUV)
180 Battery - 16:43 Total trip / 3:36 of that is charging
135 Battery - 17:39 Total trip / 4:15 of that is charging
105 Battery - 19:13 Total trip / 5:06 of that is charging

 

[HostileHarry]

A bit more info from an e-mail a member in a Rivian forum got from the company:

•Their goal for service is that it will be done at your location or you will be given a loaner and the vehicle trucked away.
•

I saw this same response on one of the Rivian forums. This has absolutely no scale, which is my personal biggest concern. We are already seeing the challenges that Tesla is facing with service AND they have their own service centers. My assumption is that Rivian's early adopters will have that same white glove experience early Tesla owners experienced, but as they grow, they will suffer from their lack of scale. I really wonder why they won't take the route of utilizing Ford's dealer network as their long term solution to meet demand and scale.

 

[acoste]

So I played with ABRP a little bit more this morning to test out a trip from my home in IL to Denver International Airport, which is roughly 1000 miles. Here is the breakdown for estimates from ABRP.

Tesla (Total trip time hr/m):
Model X Raven - 16:20 Total trip / 2:50 of that is charging
Model X 100D - 16:57 Total trip / 3:19 of that is charging
Model X 90D - 18:08 Total trip / 4:17 of that is charging

Rivian R1S (the SUV)
180 Battery - 16:43 Total trip / 3:36 of that is charging
135 Battery - 17:39 Total trip / 4:15 of that is charging
105 Battery - 19:13 Total trip / 5:06 of that is charging

ABRP seems to overestimate the tapering for the battery. That affects the results quite a bit. Wait for the real world data.
Additionally non Tesla charging network isn't great in the US. Much better in the EU. Over there you won't find much difference even with this inaccurate tapering curve.