Rivian R1T & R1S: Is Electric Battery Pack Designed Right? Video

FEB 9 2019 BY ERIC LOVEDAY 39

We believe in Rivian’s battery design, but apparently, some question it.

Called into question is the design of the Rivian R1T electric truck and R1S electric SUV battery packs. Are there really design considerations that need to be fixed?

Well, if there are, we believe in Rivian and its team of engineers enough to say a fix will be implemented prior to launch. However, we’re not sure there’s an issue here.

The video focuses on cooling of the cells in connection to the unique 2170 double stack. The cooling side has been only partially explained by Rivian. What we do know is that the cooling plate is there to support the cells above. This doesn’t necessarily imply that cooling ends there though (see graphic below with blue spacing between cells). There could be additional between-cell cooling. We’re just not quite sure if that’s the case yet.

We should further note that thermal runaway events have not often been reported with 2170 Tesla cells. It was seemingly more common with the 18650 cells and, in particular, with the Model S, a low-slung vehicle that has its share of objects impact the battery.

Lastly, Rivian has a different approach to battery protection and, of course, much better ground clearance than the Model S. To protect the battery, Rivian states:

The pack uses a carbon composite shell and a “ballistic shield

Looking Back

As we reported in an earlier article the pack is indeed a 2170 double stack. A 7 mm flat cooling plate is sandwiched in between the 2 layers of cells.

Rivian’s solution to battery thermal management is the use of a cold plate that’s placed between two battery cells. A single cooling system chills both layers of cells at the same time. According to Rivian, this reduces the amount of energy needed to power the system, thereby allowing the car to have better range in all types of conditions. In addition to saving power, the cooling system’s design allows for tighter packaging of cells within the modules. According to Farquhar, Rivian’s unique packaging allows the module to be 25% denser than any other battery module on the market. 

 The different kWh pack sizes are made by including different numbers of modules. Each module has 864, 2170 cells (432 cells in each layer).

Although not verified by Rivian, customs import records indicate LG Chem is the manufacturer.

What About Battery Heating Though

What we lack knowledge on is what Rivian refers to an as advanced heating system. Rivian is not yet openly sharing that heating info, other than to basically say that cold weather won’t impact the range of the R1T or R1S.

Again, we must mention that battery heating is surely included in Rivian’s design. However, the details on this seem a bit under the wraps still. But we were told to expect the strongest cold-weather performance of any EV from Rivian. This was before the LA debut, back when we visited Rivan’s facilities in Plymouth, Michigan. Unfortunately, even still today, that info is largely off the records and under wraps. We do expect this battery heating info to become known well ahead of the sales of the R1T and R1S though.

Order Away

Go ahead and place that pre-order (and discuss it on our Rivian pre-order thread on our forum here). We have confidence in Rivian’s engineering abilities.

It’s not as though Rivian sprung to life yesterday. The company is a decade old, ya know.

Categories: Rivian, Trucks

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39 Comments on "Rivian R1T & R1S: Is Electric Battery Pack Designed Right? Video"

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Cooling on the side of the batteries is better than then cooling the top or bottom because there is more surface area to dissipate the heat. It would also allow the batteries to slightly larger which should decrease the production cost and assembly complexity.

Logically I would expect the plate to have fins that act like a radiator bonded to the cooling plate, but don’t have direct fluid contact. Easy enough to manufacture and plenty of surface area.

I am more curious how the battery connections on the bottom half work— is the battery pack weight resting on them, or is weight supported some other way?

That’s intuitive, but not necessarily correct. I just learned recently that because of the way that the cells are wrapped, they actually conduct heat far better axially than radially, so cooling on the ends of the cells ends up being about as good as cooling on the sides, but of course way easier to pull off and slightly more space efficient. I will say, however, that I’m a bit surprised that Rivian wouldn’t want to cool both ends of the cells… They have to connect busbars at both ends anyway, they might as well run some coolant though those plates.

Cylindrical cells essentially have a higher thermal resistance radially versus axially. There is an equalization point where you can match the axially cooling with radial cooling, but the surface area required to do so is extremely high and begins to affect your space efficiency.

I have no doubt Rivian has done their homework.

smarter than the rest. They seem to have studied Tesla and use their tech. Very smart.

The only long term issue with this is the temperature gradient along the height of the cell.

Rivian has a contract with Munro and Associates (the top automobile consulting firm in the USA) likely to look for areas in which a given Rivian model could be designed better and/or for manufacturing consulting. And Munro and Associates does have a battery guy working for them.

I’d love to see a thorough review like Munro did for the TM3 (the later, more complete review, rather than the first rush review).

When the author said, “I wonder if Rivian did any test …” I stopped. Too much speculation compared to facts and data.

Yup. I knew less than a minute into this video that this guy is pretty clueless. I watched the rest of it just to see how many gross errors of fact and absurd assumptions he made, not because I thought I would learn anything.

> cold weather won’t impact the range of the R1T or R1S

Only possible if their batteries need no heating, and thrive in cold conditions, but if they do need heating, where do you think the energy for that comes from? I guess, they can use waste heat from the motors, but that takes time to develop, after driving for awhile.

Sounds too hard to believe, that will not impact range.

It’s possible they’re storing heated coolant in a vacuum flask like the Prius, and then using it to heat up the batteries faster.

That’s going to be one hell of a thermos to heat up a tonne of battery from -15°C

Agree, but am willing to be surprised.

Article sez:
“Again, we must mention that battery heating is surely included in Rivian’s design. However, the details on this seem a bit under the wraps still.”

For more details about the Rivian battery, battery heating and cooling system, and other cool facts about the Rivian powertrain see:

https://electricrevs.com/2018/11/29/rivian-the-powertrain-details-you-wont-read-about-elsewhere/

Thanks for the link. Good details and not at all ‘under wraps’. It would appear the ‘plate’ has antifreeze/water flow through it and the motor/etc are similarly liquid cooled. There’s also a radiator in the traditional spot just behind the grill and also a ‘heater core’ just like every ice car. The coolant loop through the battery plate is also used as heating loop. So depending on the whether and other factors, the battery pack and motor are cooled via this loop and the hot liquid is routed to a radiator with fan just exactly like an ice vehicle. In cold weather (heat needed) the radiator is isolated from that loop (as long as cooling isn’t needed) and the cab is heated at least partially by the standard heater core via excess heat from the motor and battery pack. When it’s really cold, the battery pack has a heater. Although your article doesn’t specify that piece, it stands to reason that this heater is a resistive heater that heats the fluid rather than direct heat. This minimizes size, cost, and complexity of the heater. One other note on the plate going between the two slabs of batteries. Newton’s laws of… Read more »

Thanks for your detailed summary of the physics and engineering involved! Too bad the guy who created this video doesn’t even remotely have your grasp of the engineering involved.

one thing that surprises me, is that both tesla and Rivian, choose to use a flat hose that was then interwoven between batteries. That is a long hose, which means that the end battery will have higher temps, then the initial one (with higher temps being far more damaging, then losing a bit of energy due to cold).
It seems to me that a more efficient way would be to wrap each cell and then run from top to bottom of the cell. With that approach, you have a distance of only 70 mm, instead of some 70+ cm.

The Model 3 pack does use shorter cooling loops than Model S/X packs, and does handle waste heat better.

But if an engineer wants to reduce the temperature difference between the start of a loop running thru a battery pack vs. the end, all he needs to do is increase the flow rate. What you’re proposing, a separate loop for every cell, would be unnecessarily complex and expensive in a pack which, like Tesla’s and Rivian’s packs, contains thousands of cells.

The Chevy Volt and the Bolt EV cooling systems do put a cooling plate between each pair of the much larger flat cells in those packs, so would be a lot closer to what you’re suggesting. That involves a lot more parts and a lot more connections which have to be water-tight under pressure, so I would guess they are more expensive.

George Bower, who has written many EV engineering articles for IEVs, thinks the Volt/Bolt EV system is more effective at heat transfer than the Model S/X system. I don’t know about a comparison between the Model 3 and the Volt/Bolt EV cooling systems.

The very thin Volt plate sandwiched between the pouch cells in the pack have coolant channels running inside them with no shared coolant plate below. This is a very aggressive cooling design that was done due to the high power density of the Volt cells.

The Bolt EV design also places thin aluminum plates between the pouch cells but they have no coolant channels and are just passive heat sinks to help transfer heat down to the shared coolant plate running underneath the pack. The Bolt EV battery operates at lower power density than the Volt battery. Instead, the Bolt EV cells and pack are focused on maximizing energy density.

I weep for the state of ignorance displayed by wannabe armchair engineers. Someone posted a comment to YouTube about this video: “Someone needs to look up Dunning-Kruger effect”

Yeah, that sums it up pretty well. This guy knows much, MUCH less about EV li-ion battery packs than he thinks he does. It would take a rather long thesis to explain every place he’s wrong, but let me hit a few of the low points:

1. It’s true that if the battery pack gets big and heavy enough, at a certain point you hit the law of diminishing returns, and more capacity won’t take the vehicle further because it will be too heavy. However, the range of 180-200 kWh with cells of the approximate energy density (and weight) of current BEV cells certainly isn’t anywhere near that limit. I guess this guy doesn’t know that Tesla is planning on putting battery packs of something like 600-800 kWh in its Semi Truck.

(continued…)

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2. We don’t have any idea just how Rivian is going to engineer its battery pack for effective cooling. The idea that it will be just a simple flat plate is IMHO pretty naive. Rivian has been working on
EV design for some years, and it’s rather difficult to believe they are as clueless about heat transfer out of battery cells as this guy suggests. He’s right to say that simply resting one end of tall cylindrical cells on a flat cooling plate would be insufficient, but instead of making the logical conclusion — that Rivian has designed a cooling system more effective than that — he’s jumped to the conclusion that Rivian doesn’t know what the heck they’re doing.

3. His reference to lithium plating again shows ignorance of the subject. That happens when you try to charge li-ion cells that are at freezing temperature (of water) or below… not to cells which are overheated!

Also… his choice of monotonous light jazz music for this video is both inappropriate and annoying.

Few points…First, more batteries means they may be able to run at a lower charge/discharge rate than Tesla packs, and may have a lower overall peak C draw where the most heat would be generated. Second, how much of the cooling hose on the Tesla pack is making contact with the cell versus its total surface area, versus the Rivian plate solution? Third, unlike Tesla, will the Rivian 2170 cells have top vents that help with heat dissipation? Lastly, is it possible Rivian may have added air flow across the tops of the batteries to help dissipate the heat?

I do wonder if Tesla’s spacing is completely due to heat, or if it also may have to do with being able to add padding around all of the cells in the case of a crash to avoid breaching the cells and causing a fire.

They haven’t released the flow rate of the glycol through the battery. Its trivial enough to have a sufficient water flow so I think the part of the picture where he has cold glycol in , and hot out – only varies by a few degrees due to the high specific heat of the glycol mix, assuming they have more than a trivial amount of glycol flow through the battery.

As far as the battery temperature gradient itself – I would imagine either the casing can transmit the heat effectively – but you would think that the cell manufacture’s recommendations would have been followed since no one knows better the performance of their cell.

Its a simple calculation to figure out the heating of various objects once you get the recommendations of the cell manufacturer. Any video should provide that but you would assume engineers either at the cell manufacturer or Rivian would have thought the problem through.

I can’t believe that the Tesla engineers didn’t think of this simple and low cost method of cooling the battery cells. But they rejected it in favor of a much more costly method. Why?

Because the simplistic method describes almost certainly wouldn’t provide adequate cooling. The surface area involved in heat transfer is much smaller, compared to the entire surface of the cell, than what Tesla uses in the Model 3 pack. That would limit how fast heat can be transferred out of the cell, leading to heat buildup and eventually a fire.

Bill Howland has a clever suggestion in this thread: Use the cell’s metal “can”, or casing, to enhance heat transfer. But I think that would have to be coupled with some way of making better contact with the cooling plate than just resting the bottom of the cell on top of it. Perhaps some sort of socket for each cell, or fingers attached to the cooling plate, in a perpendicular direction, which extend upwards along the side of each cell.

Remember, cylindrical cells by design conduct heat more efficiently axially versus radially. Although there is a clear surface area difference, you can achieve the roughly the same rate of heat removal as you would with the Tesla partial side interface. The next challenge for axial-only cooling is the temperature gradient, but you still have to solve electrical isolation on both methods which tends to add more to the equivalent thermal resistance.

No disrespect to anyone, but it is laughable that some people here or elsewhere online would be pointing out battery design errors. And then you wonder they like to keep always things close to their chest???

What’s next, YouTube cancer diagnosis and treatment? …. Please.

Yeah the loudest mouths here have proven they know almost nothing about basic physics – and as far as engineering is concerned – have never been able to accurately PREDICT ANYTHING, which is an engineer’s job in the first place – to predict final performance from an as of yet untested design.

I’m with you – I’d trust Rivian engineers and Panasonic battery manufacturing engineers before trusting the more dopey people here.

Does this kid realize this base cooling architecture is whats used in the gen 2 formula E battery? If it works there I think it will work for soccer moms just fine.

I also doubt this will be the last time we see this thermal architecture.

Any details on that?

I just hope they make a drop down “Frunk” gate so it can be accessed without scratching up the fenders. (or accessed ALL practically!)

Here is a Rivian patent titled ELECTRIC VEHICLE THERMAL MANAGEMENT SYSTEM WITH BATTERY HEAT STORAGE:
http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1=20180086224

That patent is already linked-to in my article (see earlier comment above) that was published over 2 months ago.

This patent may or may not exactly match the actual design in their prototype vehicles.

Their prototype design, described to me by Rivian execs at the LA Auto Show shortly before I found that patent, is similar.

I am surprised at how these are done.
Basically, straps. that flow around about 1/2 of the battery from right to left in the pac, in basically a flat hose similar to a small firemen’s hose.
How about instead wrapping the battery and then running the fluids from top to bottom?

That should say, how TESLA’s are done (no edit).
I am also surprised on Rivians, but I have a funny feeling that there is more going on than is reported.
It is possible the batteries are simply immersed in oil, as opposed to glycol, so as to transmit heat to the

Why not ask them to provide some engineering details? They can only say no.