very interesting video of Lithium batteries and the cold problem.
they show a HD that is in stone cold (upper 20'sF) with a lithium battery.
what they are showing here is during the crank stage the battery will produce internal heat. They will do a short crank, let it sit for a couple seconds, do another short crank, let it set and each time you see how the battery works better as it heats up with internal heat. Long story short, after battery warms up from it's own internal heat, bike cranks fine.
PS: Watch the volt meter when he hits the starter button.
Remember as the voltage goes down, the required amperage goes up. I bet that voltage drop could weld the starter relay in the start position (Which does happen to older K100's with low batteries).