The GMC Hummer EV lineup’s performance credentials are staggering: an expected 0-60 mph time of 3.0 or 3.5 seconds in its Ludicrous-like Watts To Freedom (WTF) mode, the diagonal dance enabled by Crab mode and its four-wheel steering, the heavy suspension lifting of Extract mode, and an EPA range targeted at more than 300 or 350 miles in the Hummer EV SUV or Hummer EV SUT pickup, respectively. 

But for modern electric vehicles positioned to fully replace gasoline models, the charging time is just as important. And what GM is revealing about charge times for the Hummer EV says something about a generation of Ultium EVs on the way, all powered by the same large-format pouch cells, co-developed with its production partner LG Chem and potentially arranged in several different configurations. 

2022 GMC Hummer EV

2022 GMC Hummer EV

The SUT, with its somewhat larger 24-module pack (roughly 213 kwh gross capacity) afforded by its longer wheelbase, will offer 350-kw DC fast-charging, while the SUV, with its 20-module pack (around 178 kwh), will charge at up to 300 kw. 

What that means is that with a CCS connector from high-power, 800-volt compatible charging hardware, the Hummer EV SUT is capable of regaining nearly 100 miles of range in 10 minutes. The Hummer EV SUV isn’t far behind, at nearly 100 miles of range in about 12 minutes.

In an interview earlier this week, we asked GMC Hummer EV chief engineer Al Oppenheiser what this means at the 400-volt CCS charging hardware that still occupies many roadside stations. 

400V charging will be speedy, too

The short of it: The Hummer EV won’t be saddled with a 50-kw rate. Oppenheiser said that in a test vehicle he went from 30% charge to 90% charge, on 400-volt hardware, in about 45 minutes—an indication its 400-volt power will peak at 150 kw or higher for a big portion of the charge curve. 

2022 GMC Hummer EV

2022 GMC Hummer EV

Oppenheiser said that GM has a patent pending for the way it minimizes mass in the cooling system, reducing bulk versus traditional HVAC components, while allowing some of the advantages of a heat pump. The system, as with many of the latest EVs, has the capability to cool the battery pack using refrigerant, when it’s being charged, or to warm them on a cold morning. 

In a Q&A with the media on Monday, Mike Colville, GM’s senior manager of electric vehicle integration, said that if your destination is programmed into the navigation system the battery will be preconditioned to the ideal temperature for charging. 

A charging-savvy trip planner for on- and off-road 

Very fast charging is only part of the puzzle, though. Finding the chargers, and coordinating your route around charging stops, is perhaps even more important for quashing range anxiety. 

2024 GMC Hummer EV SUV

2024 GMC Hummer EV SUV

The team behind the Hummer EV recognizes that owners will want to take trips that combine on-road sections and off-roading, which creates a complicated puzzle solved by a familiar name: Google. 

“With our Energy Assist app, and a trail map that goes with our Google Automotive Services, you'll be able to plot your entire trip before you put your first mile on the vehicle,” said Oppenheiser.

2024 GMC Hummer EV SUV

2024 GMC Hummer EV SUV

The trail map will know the elevation grade, the amount of rock-crawling, and other factors in energy consumption, he says—all in the interest of avoiding range anxiety in the first place. 

Will GMC Hummer join Rivian and Jeep?

GM hasn’t yet revealed whether it will invest in off-road-focused charging locations like Rivian and Jeep, though. Last year the company announced a partnership with EVgo that will result in the installation of more than 2,700 DC fast-charging connectors—all powered with 100% renewable energy—over the next five years. Getting a few of those on the route to outdoor getaways sounds a lot like Watts To Freedom to us.