An In-depth Explanation of GM’s Ultium Battery System for the Layman

Here’s An Exceedingly Nerdy Explanation of GM’s Ultium Battery System

The GM Ultium platform, utilized by the Cadillac Lyriq, features modules comprised of 103 amp-hour (Ah) pouch cells using the NMC chemistry. Each cell has a peak voltage of around 4.2V and a nominal voltage of approximately 3.6V. The Chevy Bolt will also incorporate the Ultium platform but with a lithium-iron-phosphate chemistry that operates at lower voltages.

The Lyriq’s battery configuration consists of 24 cells per module in an 8S 3P setup, resulting in a nominal module voltage of 29V. These modules are connected in series to create the Lyriq’s 96S pack configuration. This design highlights GM’s confidence in the lower voltage architecture of the Ultium system.

The Hummer EV shares the same cells and modules as the Lyriq, but with a pack configuration of 96S 6P, essentially two Lyriq packs stacked together. Despite operating at 400V, the Hummer can charge at 800V through contactors that connect the pack’s two halves in series.

GM’s focus on production volume over higher drive voltages aims to reduce costs initially. The system’s discharge rates remain impressive, with the Lyriq capable of continuous charging at 190kW and regenerative braking harvesting up to 240kW.

Further advancements in charge/discharge rates are expected in the Lyriq V performance version, without altering the core cell. GM continues to explore the potential of its systems through analytical methods and test data correlation.

As GM dives deeper into electrification, there is potential for different configurations and form factors to be unlocked for future EVs. The Ultium system’s versatility and adaptability signal an exciting era for Electric vehicles.