Today during Thor's live stream of the dealer open house while doing a walkthrough of the the new
Sequence 20K they mentioned that the Sequence line now has a Lithium option which ditches the generator for two "5500Watt" Lithium Ion batteries and an extra 200 amp alternator on the engine for charging. In addition to that they said the main engine has an autostart (similar to the ones for generators) when the batteries get low. (Also included is 190watts of solar.)
I'm guessing they mean 5.5kWh batteries for 11kWh total.
Very interesting, here is the video: