Are you excited or dissapointed?

[godfodder0901]

I agree about being nervous about the batteries. There is something wrong here. They couldn't even put together a full 135 battery pack for Rebelle....

It was the full 135 pack, but limited to 70-75%.

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[SleepySheepie]

It was the full 135 pack, but limited to 70-75%.

75% isn't a full pack.

 

[discsinthesky]

75% isn't a full pack.

I think it was limited by computer, not by an actual battery pack constraint.

In either case, I think it makes a lot of sense for Rivian to start with the 135 kwh pack first, which informally seems to be the most popular option. Add to that the idea that they are probably making more profit on four 135 kwh trucks than on three 180 kwh trucks and it seems like a slam dunk. Based on what's been coming out of Tesla, it seems like the industry is generally pretty battery limited in the short-term, so I see the logic in managing supply to generate the most profit.

 

[DucRider]

It was the full 135 pack, but limited to 70-75%.

75% isn't a full pack.

You never have access to 100% of the pack capacity. They likely greatly increased the upper and/or lower buffers from what will be available on production units.
Having a battery issue during the rally would have been a disaster. They went the "belt and suspenders" route (with maybe some duct tape just in case) to make completely sure there were no issues.

Also worth noting that Rivian seems to be going away from listing pack size (which can be stated as actual or useable) and relying only on terms like "Large" for the 300+ mile vehicles. Likely we will see something along the lines of "Standard" and "Extended" or "Long Range" for the other options.

Since the kWh rating of a pack is actually a variable that changes with temperature and load, relying on a standardized system like the range tests defined by the EPA makes at least some sense.

 

[ajdelange]

75% isn't a full pack.

75% of what?

It's been discussed here many times before. The capacity of the battery is what the manufacturer says it is and that is arbitrarily set by the manufacturer as being the amount of charge one can take out of it in discharging it from one arbitrarily chosen voltage called "full" and another arbitrarily voltage called "empty". Note that the "empty" voltage is not 0 volts and the full voltage is not the open circuit voltage at which all the lithium is in the anode. This is because you want to stay well away from either of those voltages as operating close to them is detrimental to battery life.

The manufacturer wants to get Ve and Vf as far apart as he can without going into the caution or danger zones as this allows him to claim more range but he want's them as close together as is necessary to deliver a reasonable number of charge/discharge cycles (life). Not publishing battery capacity gives him maxiumum flexibility in this regard and in his marketing and adjust his available "range" just by adjusting those two voltages in firmware. Tesla has done this.

Telsa batteries have a part number sticker on them that used to say what the battery capacity was (in kWh). No more.

Besides all this batterys' capacities are not reckoned in kWh. They are reckoned in terms of the number of units of charge one can take out of them between the two defined voltages. That corresponds to some amount of power which depends on the voltage vs SoC curve which in turn depends on the rate at which current is withdrawn. So it gets complicated. There would need to be a standard (and for all I know there may be one or several ).

Since the kWh rating of a pack is actually a variable that changes with temperature and load,

Last week I would have agreed with that. This week I'm not so sure. I did some experiments with the lithium batteries used in hand drills. To my great surprise their open circuit voltages did not change as much as 10 mV between room temperature and soaking in the freezer for several hours (the packs have a thermister built in so you can measure their temperature with an ohm meter). Now these aren't the cells used in the Rivian or the Tesla so my single experiment can't be interpreted to mean that this is the case for all lithium ion chemistries but it is thought provoking. If true it implies that the stored energy is the same in a freezing battery as in a room temperature one and of course were that not the case we would have to ask where the deficit or surfeit energy went to or came from. Of course when the battery is cold the ion mobility will be low so some of that stored energy will be used to get those ions moving during discharge (thus warming the cell) and that energy won't be available for traction (or any other use). But once again First Law suggests that this will be the case. Now that's all over the map with nerdspeak but what it says is that kWh capacity isn't going to change that much with temperature, especially at models discharge rate.

 

[DucRider]

Last week I would have agreed with that. This week I'm not so sure. I did some experiments with the lithium batteries used in hand drills. To my great surprise their open circuit voltages did not change as much as 10 mV between room temperature and soaking in the freezer for several hours (the packs have a thermister built in so you can measure their temperature with an ohm meter). Now these aren't the cells used in the Rivian or the Tesla so my single experiment can't be interpreted to mean that this is the case for all lithium ion chemistries but it is thought provoking. If true it implies that the stored energy is the same in a freezing battery as in a room temperature one and of course were that not the case we would have to ask where the deficit or surfeit energy went to or came from.

From LGs spec sheet on the 21700 likely used by Rivian:

Even if this isn't the exact cell, it is likely that there will be at least a similar degree of temperature dependency.

 

[Babbuino]

Sounds like the TFL guys are on the dissapointed size

 

[thrill]

Sounds like the TFL guys are on the dissapointed size

Figured out long ago that's a toxic channel.

 

[R1Simon]

Does anyone know if the Amazon van is of the 135 kWh variant? If that’s the case, they may have chosen to start with the 135 to simplify manufacturing. Launching three vehicles simultaneously comes with challenges, limiting to one battery size out of the gate would help simplify things.

 

[zmachine]

Does anyone know if the Amazon van is of the 135 kWh variant? If that’s the case, they may have chosen to start with the 135 to simplify manufacturing. Launching three vehicles simultaneously comes with challenges, limiting to one battery size out of the gate would help simplify things.

I've read somewhere that it will have different battery capacity for different utilitisation and location.

 

[trickflow]

I think it was limited by computer, not by an actual battery pack constraint.

In either case, I think it makes a lot of sense for Rivian to start with the 135 kwh pack first, which informally seems to be the most popular option. Add to that the idea that they are probably making more profit on four 135 kwh trucks than on three 180 kwh trucks and it seems like a slam dunk. Based on what's been coming out of Tesla, it seems like the industry is generally pretty battery limited in the short-term, so I see the logic in managing supply to generate the most profit.

Then you can have the argument that they would make even more profit on the smallest pack, why not start with this one first. If I were a betting man, I would say that there are technical issues with the largest pack. And what everyone else is also saying about the Rebelle rally... Think about it, that would have been the time to stress the batteries to the fullest capacity (even remove the upper and lower limits) so you can take it back the R&D and see how much a stressed battery degraded. I think there is an issue the the BMS or architecture, but this is just my speculation.

 

[DucRider]

And what everyone else is also saying about the Rebelle rally... Think about it, that would have been the time to stress the batteries to the fullest capacity (even remove the upper and lower limits) so you can take it back the R&D and see how much a stressed battery degraded.

Think about the PR nightmare if there would have been a battery failure/issue during the rally.

 

[jimcgov3]

Did we ever determine if the Amazon delivery vans count against that total?

https://www.irs.gov/businesses/plug-in-electric-vehicle-credit-irc-30-and-irc-30d

Quoted from the website:

Internal Revenue Code Section 30D provides a credit for Qualified Plug-in Electric Drive Motor Vehicles including passenger vehicles and light trucks.


Are the Amazon vans classified as light trucks? I would say no, but this is out of my wheelhouse.

 

[trickflow]

Think about the PR nightmare if there would have been a battery failure/issue during the rally.

Think about the PR issues that people are saying the truck can't go more than 60 miles in the sand.....

 

[timesinks]

I haven't double checked the code itself, but the irs website says any 4-wheeled vehicle under 14k gross weight. So unless the Amazon vans are dulies, I would bet they're going to qualify.

https://www.irs.gov/instructions/i8936

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