# GM Ultium batteries



## rmay635703 (Oct 23, 2008)

Once we start getting wrecked ultiums I will drop one in my c-car


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## remy_martian (Feb 4, 2019)

They’re designed to sit on a cooling plate. I don’t think a module will just “drop in”


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## brian_ (Feb 7, 2017)

The caption for the first image includes this:


> You can tell from the tires it's a truck frame, and if you click on the image to enlarge it, you might be able to see that the cells are aligned vertically, which GM says allows for better energy density at the cost of a taller pack.


The cells in the Volt, Spark EV, and Bolt are all vertical (standing on edge). For some reason GM's marketing people decided to hail the ability to place the cell plane either horizontally or vertically as some sort of big advance, and the writers who know almost nothing about EV designs are running with that.


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## brian_ (Feb 7, 2017)

Here's the GM statement about that orientation issue, as paraphrased by the writer of this article:


> GM has gone for a pouch cell design for the Ultium batteries, which can be configured in different ways depending on the vehicle and its needs. For a big pickup or SUV, that means pouches arranged vertically in the modules (i.e., with their second-longest edge vertically), which GM says is best for energy density, but at the tradeoff of a taller pack. For cars that need something a little lower profile, the pouches can be stacked on top of each other in a module.


This all makes sense, but it's not new. The Volt, Spark EV (2014+), and Bolt all use LG Chem pouch cells. Almost all current production EVs other than those from Tesla use pouch cells. The original Nissan Leaf battery design (but not the new 63 kWh variant) places pouch cells horizontally under the seats and rear seat floor, but vertically under the rear seat where more height is available.


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## brian_ (Feb 7, 2017)

rmay635703 said:


> Once we start getting wrecked ultiums I will drop one in my c-car


With not much change from the Bolt battery - at least from the limited descriptions available so far - you don't need to wait... just use the Bolt bits. If you really mean the whole pack... that's tough in any vehicle because packs and vehicles are designed to go together; what do you mean by "c-car"?


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## brian_ (Feb 7, 2017)

remy_martian said:


> They’re designed to sit on a cooling plate. I don’t think a module will just “drop in”


That's an important point: there's substantially more to designing and building a pack than just packing a bunch of them in a box. That's especially true for modules needing active thermal management, and most challenging for modules like this which need an external heat transfer plate.


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## brian_ (Feb 7, 2017)

The article says:


> GM says that a car would use between six and 12 modules in a pack, with up to 24 in a 200kWh, 800V double-layer battery pack for something like the 1,000hp electric GMC Hummer that was trailed at this year's Super Bowl. (The smallest six-module packs would be 50kWh units.)


That's just about 8 kWh per module, or one-third more capacity than the larger of the two current Bolt module sizes, which have a 10S 3P configuration. The higher-capacity pack configurations would presumably have half as many cells in series (and twice as many in parallel) in each module to get 400 V in 12 modules and 800 V in 24 modules, with the same 8 kWh per module.


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## Tremelune (Dec 8, 2009)

And now the motors:









This is GM’s new series of Ultium Drive electric motors


GM will have 22 new EVs on sale by 2023, and they'll all use these motors.




arstechnica.com


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## brian_ (Feb 7, 2017)

Tremelune said:


> And now the motors:
> 
> 
> 
> ...


No surprises, but it's good to see some information. Now for some notes about details that are suggested by this material, but not specifically mentioned in the article...

The motors are bar-wound (or "hairpin"), like the Remy (now BorgWarner) motors that they used in the Two-Mode hybrids and the motors in the Spark and Bolt. An SAE paper about the design of the Bolt motor mentioned going to 6 conductors per slot from the Spark's 4 conductors per slot, but the image showing hand assembly of a pre-production motor looks like they're back to four, at least in this particular motor.

Ignoring the nonsensical wording ("induction magnet") it's interesting to see that they are taking the approach of using permanent magnet synchronous motors in general, but induction motors to minimize drag (and cost) where the motor is normally spinning unpowered (the "assist" unit).

It appears that GM is moving away from the hollow motor shaft and concentric (motor and axle) configuration of the Spark and Bolt to a more conventional layout... although not all units are shown in detail. The AWD assist unit seems to be the exception, appearing to be a concentric design (with a strange extra housing protrusion, unless it's a dual-motor unit which would be good).

In the AWD set of components on display, the rear unit appears to place the motor behind the axle line, while the front motor is ahead of the axle line. This makes sense to maximize space available within the wheelbase for the battery pack. Of course the difference between front and rear units is primarily that the inverter package is on top of the front unit (and the truck unit), and on the side (front side) of the car rear unit to minimize height.

Only three motors - one of which is an assist unit that is probably quite low-powered - doesn't seem like much variation for the company's entire product range. It will presumably be like the generation of Nissan Leaf: one motor limited to various power levels due to other components of the system (mostly battery), so the smallest cars haul extra motor weight around and the most powerful run the motor at screaming high temperatures if pushed hard. That might be okay, and will make aftermarket modification and DIY use easier.


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## Tremelune (Dec 8, 2009)

I'm hoping the compact packaging allows them to put them in wildly different cars that only need similar power delivery...Millions of "standard" motors flooding junkyards like so many small blocks...


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## brian_ (Feb 7, 2017)

Tremelune said:


> I'm hoping the compact packaging allows them to put them in wildly different cars that only need similar power delivery...Millions of "standard" motors flooding junkyards like so many small blocks...


That is how it works with engines now - a Corvette and a Silverado pickup are not similar, but have the same engine with only tiny variations. The drive units will be even more similar, because much of the performance variation between vehicles will be due to battery differences. The nice thing about the EV drive units is that nearly every wrecked vehicle will a source of a salvaged drive unit or two, since the motors and very simple gearboxes should have no problem outliving the vehicles that they're in.


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## Duncan (Dec 8, 2008)

"I'm hoping the compact packaging allows them to put them in wildly different cars that only need similar power delivery...Millions of "standard" motors flooding junkyards like so many small blocks. "

And that is why this is such an awful idea!
GM has NOT got the message!
An EV is not a petrol car with a different power unit

To be a good EV you need to throw away all of the petrol bits and design the car from scratch as an EV

If you don't do that you get a dog and Tesla eats your lunch

Having deep "parts bins" was an advantage in the petrol days but turns into a disadvantage when the market changes to EV's


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## brian_ (Feb 7, 2017)

Duncan said:


> "I'm hoping the compact packaging allows them to put them in wildly different cars that only need similar power delivery...Millions of "standard" motors flooding junkyards like so many small blocks. "
> 
> And that is why this is such an awful idea!
> GM has NOT got the message!
> ...


Duncan, I think that you completely misunderstood the comment. There is no use of petrol engine powertrain components in the new GM products. Just like with engines, there are components which can be used over a range of vehicles: just as one engine family works in both sports cars and pickup trucks; one EV drive unit can work in various cars. Tremelune is just hoping that after a few years of production there will be many interchangeable GM EV drive units in salvage yards, just as there are now many nearly interchangeable GM small-block V8 engines in salvage yards.

And although this discussion is only about powertrain, much of a vehicle really is the same regardless of powertrain. A Tesla Model S/X rear suspension is nearly indistinguishable from the many large sedan "integral link" suspensions in many brands of cars; a Tesla Model 3 rear suspension is indistinguishable from the common five-link IRS systems in everything from Mercedes sedans of the 1980's to current Mazda Miatas.


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## Duncan (Dec 8, 2008)

Hi Brian
Nope I understand the ideas - but I can also see that the old car engine thinking is prevalent in the GM organization

With a dino burner the engine is the "core" you build the car around the engine

GM are using the same thought train with these engines - and its simply the wrong way of thinking with an EV

The "core" of an EV is the battery - the motor is small enough not to be a major issue


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## remy_martian (Feb 4, 2019)

Management apparently wants to spit motors out like jellybeans and minimize production types, so telling the engineers, "here are the motors, go design your car", which seems opposite to Tesla's bespoke motor per model (which is not sustainable as competition heats up) and I think is the winning strategy to bring sub-$30k EVs to market. Tesla will soon have several motors as well, I'd suspect.

I agree the battery is the core of the vehicle platform design, but frankly I'm not thrilled with GM's idea of a wireless BMS. Too much PowerPoint in these established companies.

More interesting to me is the steering rear wheels on the new eHummer. Seems to have a lot more angular compliance than the rear steer in my GMC. There's around a 2HP motor back there in mine to move the wheels....range sucker.


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## remy_martian (Feb 4, 2019)

brian_ said:


> No surprises, but it's good to see some information. Now for some notes about details that are suggested by this material, but not specifically mentioned in the article...
> 
> The motors are bar-wound (or "hairpin"), like the Remy (now BorgWarner) motors that they used in the Two-Mode hybrids and the motors in the Spark and Bolt. An SAE paper about the design of the Bolt motor mentioned going to 6 conductors per slot from the Spark's 4 conductors per slot, but the image showing hand assembly of a pre-production motor looks like they're back to four, at least in this particular motor.
> 
> ...


Anyone have the PDF to that paper that they can PM to me?


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## brian_ (Feb 7, 2017)

Duncan said:


> Hi Brian
> Nope I understand the ideas - but I can also see that the old car engine thinking is prevalent in the GM organization
> 
> With a dino burner the engine is the "core" you build the car around the engine
> ...


No, you don't build the car around the engine. This is obvious, because many cars are available with a range of significantly different engines, and very different cars are built with the same engine. The engine location and orientation is an important feature of the design, just as the location, shape, and size of the battery (more than the motor) is an important feature of an EV's design.

There is nothing in the GM announcement which suggests that they are designing vehicles around the motors, or the drive units. They have just shown a set of drive units (built with only three different motors) to meet the range of requirements of their wide range of vehicles.


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## brian_ (Feb 7, 2017)

remy_martian said:


> Management apparently wants to spit motors out like jellybeans and minimize production types, so telling the engineers, "here are the motors, go design your car", which seems opposite to Tesla's bespoke motor per model (which is not sustainable as competition heats up) and I think is the winning strategy to bring sub-$30k EVs to market. Tesla will soon have several motors as well, I'd suspect.


It's strange how some people in a forum for an inherently technical activity seem to have so little respect for technical professionals. The engineers developed the motor and drive unit range, within budgetary limits approved by management in response to professionally developed financial requests. That's how the real world works; to assume that engineers are helpless idiots following whatever technical direction comes from some executive is insulting.

It's also interesting how in this discussion there are two completely opposite ideas of best practice, both supported by reference to Tesla. Either a minimum of different motors or a bespoke motor for every model and variant is right, but either way someone thinks that is what Tesla does. 

In fact Tesla only builds two models (with two body variants of each one), and they are from different generations (several years apart), so it's hard to tell what their idea of best practice might be.


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## brian_ (Feb 7, 2017)

remy_martian said:


> Anyone have the PDF to that paper that they can PM to me?


Not me - I've only read the abstract. You could try a local university with an engineering faculty - they often have SAE publications, and some allow the public to use their resources within the library. Of course, that won't get you a PDF copy, for which you would legally need to pay.


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## brian_ (Feb 7, 2017)

remy_martian said:


> More interesting to me is the steering rear wheels on the new eHummer. Seems to have a lot more angular compliance than the rear steer in my GMC. There's around a 2HP motor back there in mine to move the wheels....range sucker.


The power challenge with steering is turning while stationary (or nearly so). In normal driving, average power consumption is minimal, both because they don't turn much and because little force is required to steer a rolling tire.

I think that the independent suspension which logically appears in any AWD EV leads to easy implementation of four wheel steering, and that feature has appeal in the off-road market so it was included. With rear steering in the original design, greater steering angle can be accommodated than in the retrofit of rear steering to an existing platform (such as the Quadrasteer GMC). The rear steer motor won't likely actually run very often in practical use, even though it does have real value in many situations.


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## remy_martian (Feb 4, 2019)

brian_ said:


> It's strange how some people in a forum for an inherently technical activity seem to have so little respect for technical professionals. The engineers developed the motor and drive unit range, within budgetary limits approved by management in response to professionally developed financial requests. That's how the real world works; to assume that engineers are helpless idiots following whatever technical direction comes from some executive is insulting.


As a tech professional, I don't have to "respect" my peers. 

You, evidently, have never worked in/with a large American, Korean, or Japanese corporation. Worker bees have almost zero say in the big picture.

GM is seems to be on a "building blocks" kick. Its "platform" pitch by Bob Lutz locked the company into the Volt abomination, when Cadillac could have buried Tesla and its Model S with an all-electric ELR. Now it has this "ultium" ultimatum.

Large corporations can be pretty FUBAR. 

Its engineers are not only idiots, to use your framework, but their voices are suppressed by the career-politicians we call "management." In many large companies, engineers are given TASKS by marketing or product planners. Yes, engineers get to work on high technology content, but they get next to zero input on strategy or architecture. You call that idiocy - fine.

I'd also put out the strawman that if engineers weren't helpless idiots, there wouldn't be any advanced weapons for psychopaths to exercise power with.


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## brian_ (Feb 7, 2017)

remy_martian said:


> You, evidently, have never worked in/with a large American, Korean, or Japanese corporation. Worker bees have almost zero say in the big picture.


Actually, I worked for a quarter-century for a major North American company in technical positions. We defined the technology, within regulatory and budgetary constraints and limited by what executives could be convinced of... with some inappropriate middle-management interference, of course. No, I will not name the company.


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## remy_martian (Feb 4, 2019)

"North American", eh? 🤓

Canadian is not American by any sense of the imagination. 

School system in Canuckistan being superior may be one explanation.

You'd think it would be the same, but not even close in my experience.


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## P.S.Mangelsdorf (Dec 1, 2014)

brian_ said:


> Only three motors - one of which is an assist unit that is probably quite low-powered - doesn't seem like much variation for the company's entire product range.


From what I have seen of GM's product planning they are intending to only have something like 3 EV and 3 ICE platforms (car, truck, crossover, maybe a 7th for Corvette only) that will underpin everything. Wheelbase and width will stretch and shrink as needed to fit the body.


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