Why some 2023 EVs may fail on 600 amp fast chargers

2023 model year, and likely 2022 though no one has tried yet. It is happening on the new chargers that have 600A output capability.

The working theory is that the Hummer (2023 and earlier) only knows of 500A output chargers and tells the charger, when at low SOC, to give it full output. The charger gives 600A, and the Hummer stops the charging session, thinking there is a problem because it has been told anything above 500A is impossible and therefore must be a fault. So it eliminates newer high-output chargers as an option because it will never go past the first initial seconds.

There might be a workaround to turn the HVAC on full blast to take on some of the power so the battery does not see the full 600A at first, but again, just a theory. Since it is likely a software issue, the odds of getting confirmation are low unless the charger companies come to bat for us.