GM is betting its electrified future on a revolutionary new battery system

When the Hummer EV SUT (sport utility truck) and its newly-unveiled SUV variant hit dealer show floors in the fall of 2021 and 2023, respectively, they’ll be among the first models in GM’s new electrified lineup to be built atop the company’s Ultium battery system.

General Motors is no stranger to the electric vehicle market. GM began its electrified venture in 1996 with the EV1, one of the very first viable battery-powered sedan models produced by a major automaker which continued its run until being discontinued in 2003. It was superseded by the BEV2 platform of which the 2016 Chevy Bolt was the first model. Today, GM relies on an EV platform powered by the Ultium battery system as the basis for the 30-plus models it plans on producing in the coming years (with 20 zero-emission models available by 2023) as part of the company’s quest to reinvent its business into that of an EV automaker — though you’ll be hard pressed to find references to a “BEV3” in GM’s press materials.

“Thousands of GM scientists, engineers and designers are working to execute an historic reinvention of the company,” GM President Mark Reuss crowed in a 2020 press statement. “They are on the cusp of delivering a profitable EV business that can satisfy millions of customers.”

During a press event last May, GM CEO Mary Barra assured reporters that the company plans to turn a profit on every Ultium EV it sells and is aiming to sell 1 million EVs annually by 2025. Of those, GM plans to release its EVs with 19 different battery pack-drivetrain combinations — down significantly from the 550 permutations currently available across its internal cumbustion fleet.

Unlike Tesla’s battery technology, which utilizes cylindrical cells (i.e. shaped like AAs), GM instead opted to use pouch- and prismatic-style cells (both of which are shaped like flattened rectangular boxes). This enables GM engineers to combine 6 to 24 cells in each module unit — the Hummer EVs have 16 to 20 modules on board depending on selected powertrain options — and then stack those modules either horizontally or vertically within the frame of the vehicle. Cylindrical, conversely, are only ever oriented vertically. With this flexibility, GM can pack in anywhere from 50 kWh to 200 kWh of energy capacity (double what the current largest Tesla battery, the P100D, can hold), translating into 350 - 400 miles of estimated range and a 0 - 60 in as low as 3 seconds.

“It's a long complicated optimization routine,” Tim Grewe, General Director Electrification Strategy and Cell Engineering at General Motors, told Engadget. Getting the most out of an Ultium battery pack of any given size “really comes down to, what are you using it for in your portfolio and how can you have the most efficiency — that's generally [with using] the biggest cell. You have the flexibility to configure those cells in any way you want,” thanks to GM’s Wireless Battery Management System (WBMS).

GM developed the WBMS in conjunction with Analog Devices. The system requires 90 percent less wiring and reduces the battery pack’s volume by fifteen percent while “improving design flexibility and manufacturability without compromising range and accuracy over the life of the battery,” according to a September press release. The WBMS is a wholly integrated system with “all circuits, hardware and software for power, battery management, RF communication, and system functions in a single system-level product.”

“The transition of battery packs from wired to wireless connectivity enables automotive manufacturers to scale their electric vehicle platforms across multiple vehicle models to meet growing consumer demand,” Patrick Morgan, VP of Automotive at Analog Devices, said. “Our wBMS solution not only simplifies manufacturing, but also allows new systems to be built on wireless data, accelerating the entire industry towards a sustainable future. We are honored to bring this breakthrough system innovation to market with General Motors.”

This management system isn’t just sleeker than its competition, it’s smarter as well. When the Ultium modules are assembled, specific details about each cell’s particular chemistry is programmed into the BMS. Not only does this enable the BMS to better balance load between the individual cells as a module ages, it should enable vehicle technicians to swap out full modules should a more effective chemistry come to market, without having to replace the entire pack. That also means GM won’t have to keep stocking cells that use the old formulation once a new one arrives — the entire production process can switch over to the new chemistry nearly immediately.

What’s more, once one of these batteries reaches the end of its automotive service life, it can easily be repurposed for other applications — such as home energy storage — thanks to the BMS’ ability to balance output between modules. “It’s a single cell that can meet all of these needs,” Grewe continued. “we do it the most efficiently while maintaining the highest quality.”

The Ultium cell’s chemistry is also unique to the industry. The Chevy Bolt, for example, used a NCM battery — Nickel-Cobalt-Magnesium. Cobalt has proven to be very effective at stabilizing a cell’s chemistry, thereby greatly extending the battery’s overall durability. However, Cobalt — while a fairly common element in the Earth’s upper crust — is produced almost exclusively in the Democratic Republic of Congo, Russia and Australia with the central African country mining more annually than the other two nations combined. The DRC is a politically volatile nation and whenever trouble starts popping off there, the entire world feels the subsequent supply pinch while cobalt exports are temporarily halted.

Unlike coup-positive Tesla, GM (partnering with LG Chem) has taken a more calculated approach to avoiding interruptions to its EV supply chain by doping its anodes with aluminum. Ultium’s NCMA (Nickel-Cobalt-Magnesium-Aluminum) batteries contain 70 percent less cobalt than NCM-based cells without seeing a notable decrease in cell durability. In fact GM and LG Chem are currently working to further develop the technology with the hope of eventually eliminating cobalt and nickel from their battery chemistry entirely.

Grewe notes that the two companies are eyeing a silicon-based hybrid electrolyte lithium metal anode, dubbed its Solid Energy System, as a successor to NCMA. “The beauty of silicon is it is just way more efficient on the periodic table and it can hold a lot more lithium than carbon can.”

“Aluminum doping was a real breakthrough that they were able to add into the cathode material to have even better life characteristics and confirmed its fundamental capability.” Grewe noted. “These cars, we'll run 'em on a fast charger much harder, and we're going to use them harder on the Hummer EV with Watts to Freedom (aka launch) mode. This dope has really made us say, 'well you can really start using [the battery system] much, much harder and have it last the life of the truck.'

“We’ve actually had a very good spring on this technology,” Grewe noted of GM’s recent research into lithium-metal last May. “We now see a very viable path with almost twice the energy density of today...that’ll easily enable 500 - 600 mile vehicles in the future."

What’s more, the Ultium system is capable of handling an 800V electrical architecture. That is, most mainstream EVs on the road today (luxury models like the Porsche Taycan, Audi e-tron GT and Polestar 2 being exceptions) as well as a majority of the DC fast charging stations, use a 400V standard, which limits the amount of energy a station can dump into your car’s depleted power cells to around 200 kW. With an 800V architecture, a DC station can pump as much as 350 kW across its line — more than double that of Tesla’s 150 kW limit. This should enable Ultium vehicles to charge faster — GM claims it can add 100 miles of range with 10 minutes of charge time — and also output some of that power to other devices (even other EVs) using an Integrated Charging Control Unit (ICCU). There’s no word yet from GM as to when or whether Ultium-powered vehicles will be capable of V2L (like the Hyundai Ioniq 5) or bi-directional charging.

GM also claims that by eliminating relatively-expensive cobalt from its chemistry in favor of more-affordable aluminum, the company may be able to get its battery price down to $100 per module by 2024. $100/module is widely considered the holy grail of EV battery technology as it is at that rate EVs achieve price parity with fossil fuel-powered vehicles. What’s more, as Doug Parks, GM’s executive VP for global product development, explained last May, cell costs currently represent 80 to 90 percent of the battery’s total price. That percentage has risen over recent years from the 60 - 65 percent range with casing, wiring and other components representing the remaining production expenditure.

“When we started with the Volt and the Bolt, we probably over-designed those battery packs. I mean, there’s a lot of really cool stuff in them and they may not ever die. We don’t have a lot of warranty (claims) with that stuff, which is beautiful,” GM president Mark Reuss told reporters in January. “But along the way, you learn how to control it, and how people really use it, which —until you do it— you’re really guessing at. So the efficiency you get out of the use of the battery along the way, where you’re decreasing cell cost and size, makes the curve of performance and value even better, independent of cell chemistry.”

“I don't know the bottom of the cost curve yet,” Grewe told Engadget. “And it continues to accelerate down faster than anybody predicted. When the initial Ultium chemistry launches on Hummer EV and Cadillac Lyriq in the next year, we project battery costs are going to be 40 percent less than today's costs. By mid-decade we're targeting that battery costs will be 60 percent less than today's with twice the energy density.” The first generation of Ultiums already pack 60 percent higher energy density than the batteries from last year’s Bolt EV, according to Grewe.

Those batteries will likely be developed and built at GM’s new Factory ZERO, though gearheads of a certain age will of course recognize it as the venerated Lordstown Complex, in northeastern Ohio. GM owned and operated the Lordstown assembly from 1966 to 2019, initially producing iconic Chevrolet models like the Caprice, Impala and Bel Air, as well as more recent compact cars like the Cavalier, Cobalt and Cruise.

“Factory ZERO is the next battleground in the EV race and will be GM’s flagship assembly plant in our journey to an all-electric future,” Gerald Johnson, GM executive vice president of Global Manufacturing, said in an October press statement. “The electric trucks and SUVs that will be built here will help transform GM and the automotive industry.”

GM has reportedly pledged $2.2 billion to overhaul and retool the site’s facilities after shutting down Lordstown in 2019 — the single largest investment in a plant in GM’s history. Once it begins operations, the new plant is expected to employ 2,200 workers and be powered exclusively by renewable energy by 2023. GM has announced plans to produce some 250 million Ultium cells a year by 2025 and, once fully online, the Lordstown facility shouldƒ produce at least 30 gigawatt-hours of batteries annually — that’s 50 percent more than Tesla’s Nevada-based Gigafactory is capable of. The Hummer itself will be produced in GM’s recently revitalized Detroit/Hamtramck Assembly plant in southeast Michigan, which was erected atop the old site of the original Dodge factory built in 1911.