Everything You Ever Wanted To Know About GM’s Ultium Platform — And More!

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Ultium. That’s the name General Motors has given to the suite of hardware and software it expects to carry it forward into the electric car future. It’s a word obviously made up by some corporate marketing types, combining the words “ultimate” and “optimum” to suggest a brave new world where GM will dominate the competition with the best electric vehicles possible.

It’s one thing to create a new marketing buzzword. It’s quite another thing to build something that lives up to the hype. The people at Motor Trend have done a deep dive into the magical mystery world of Ultium and have some insights into what it is — and isn’t.

The first thing the intrepid scribes at MT want us to know is that Ultium is not a “platform” in the same sense as the Volkswagen MEB chassis is a platform. Rather, it is a concept, a combination of battery packs, motors, and software intended to underpin a wide variety of vehicles from large to small, wide and narrow, 2-passenger to 9-passenger, sports cars to lifestyle vehicles like the obscene Hummer EV.

“It’s a shared modular battery system powering a family of related motor/drive units under the watchful eye and rigorous control of an Ultifi software operating system running on GM’s latest Vehicle Intelligence Platform electrical architecture,” Motor Trend reports. “[It’s] GM’s road map to profitably electrifying its fleet by sharing as much of the pricey hardware as possible — the battery cells and monitoring system, the essential motor architecture, and the operating system. This makes the unseen electrified underpinnings scalable across the product portfolio…..GM envisions some 19 battery and motor combinations.” By contrast, GM today has 550 engine/transmission combinations in its vehicle portfolio today.

Ultium Battery Basics

The Ultium battery uses large 23″ by 4″ by 0.4″ pouch-type cells that package energy more densely than cylindrical cells can. (See CATL Kirin battery for more on this topic.) They weigh about 3 pounds each, hold 0.37 kWh of energy, can be arranged vertically or horizontally to suit space requirements, and are typically bundled into 24 cell modules. Reportedly, the pouch cells are easier to replace if necessary and easier to recycle.

The Ultium NMCA battery uses 70% less cobalt than the battery cells in the Chevy Bolt. The aluminum is said to strengthen the electrodes and helps prevent dendrites during fast charging. This extends the useful battery life and reduces concerns about frequent DC fast charging.

Ultium marks the first time individual battery cells will be monitored wirelessly to check on battery health to detect potential issues with certain battery batches or use cases. One can certainly imagine the Chevy Bolt battery issues had a hand in showing the engineers at GM the need for such a system, although that is speculation on our part. The system will also permit flash reprogramming when retrofitting newer battery chemistries or when repurposing a pack for second life use as a battery storage device.

That ability to backfit battery cells with improved chemistries could be important in the future. GM is working with SolidEnergy (see our first story on that company from 2016) on semi-solid-state batteries that are expected to have twice the energy density of today’s pouch cells at 40% lower cost. In theory, any EV owner with an Ultium-based vehicle could retrofit those improved cells to an existing vehicle, thanks to the Ultifi software. Whether doing so would be economically feasible is an unanswered question at this point.

Each 24-cell Ultium battery module will store 8.9 kWh of electricity. In theory, 6 modules could make a 50 kWh battery pack for small, light (and less costly) vehicles or a 200 kWh pack for larger, more expensive vehicles. Need more range? Just add another module or two.

The cost of the latest Ultium batteries is reported to be around $100 per kWh — one tenth the cost of the battery for the Chevy Volt when it first went on sale 7 years ago. The Ultium battery packs will operate at 400 volts and be capable of DC fast charging at up to 250 kW. The Hummer EV will use two of those 400 volt packs virtually wired in series to simulate an 800 volt system during charging, allowing for charging at up to 350 kW.

Ultium Motor Basics

The Ultium system will offer three oil cooled axial flux motors. Two permanent magnet motors will offer 241 or 341 horsepower. The third motor is an AC induction unit with 83 horsepower that will be used to provide all wheel drive capability without the electromagnetic drag while coasting associated with permanent magnet motors. All three motors can be built using common tooling and all have an integrated reduction drive and power inverter. Motor control software adjusts the input power every 10 milliseconds, which helps make the motors nearly 97% efficient. Initially, the three motors will be offered in a total of 5 different drive configurations.

Ultifi Operating System

GM vehicles based on the Ultium architecture will utilize what The General calls Ultifi, a Linux-based operating system that enables secure over-the-air updates, vehicle-to-everything communication, and e-commerce. This is where the future of automobiles is headed.

Motor Trend says Ultifi is designed to do two things for General Motors — increase customer loyalty and generate a new revenue stream by offering subscriptions to streaming content and concierge services to selling permanent upgrades or renting temporary features over a vehicle’s useful lifetime. Some of those money makers include:

  • Vehicle authorization using driver-facing camera and facial recognition software
  • Automatic window/roof closing based on links to local weather forecasts
  • Planetarium app using GPS location to indicate nearby star constellations on the infotainment screen(s)
  • Gesundheit mode, which closes windows and activates air recirculation when pollen counts are high
  • Monitoring of nearby traffic to learn of icy/slick spots, potholes, obstacles, etc.
  • Enhanced powertrain and suspension settings for use during track days

The Takeaway

General Motors is pretty excited about its EV future and feels it will be fully competitive with offerings from crosstown rival Ford; European brands such as Volkswagen, Mercedes, and BMW; and Asian companies such as Toyota, Honda, Hyundai, and Kia. (Whether Chinese cars ever find a market in America probably depends more on politics than economics.)

All manufacturers are looking at the prospect of generating new revenue streams thanks to the wonders of digital communications. Tesla is thinking about making full self-driving available on an “as needed” basis for a fee. It’s a bright prospect for manufacturers, but will it be a hit with drivers? That’s a question only time will provide an answer to.

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Steve Hanley

Steve writes about the interface between technology and sustainability from his home in Florida or anywhere else The Force may lead him. He is proud to be "woke" and doesn't really give a damn why the glass broke. He believes passionately in what Socrates said 3000 years ago: "The secret to change is to focus all of your energy not on fighting the old but on building the new."

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