Instead of connecting the 100k resistor directly to the battery it have to be connected on the 5v on the Wemos. For now i did some quick test and voila there where some 1024 results. So it seems the A0 is working properly.
I can't understand what you mean, and it doesn't sound like the reason for the problem to me. Can you post a schematic showing how you had the 100K connected before, and a schematic showing how you have it connected now?