The first step in the design of the DIYson 2.0 is optimizing the performances. It turned out that the first EDF I had choosen was expected to run with 4S Lipos. The battery I had been using was just 2S, so it was not providing enough power. Now I have just received the new Lipo: 5000mah, 4S, 40-50C (that is also another important value, it is not recommended to go below 40C), and the difference is huge!