After a first project quite efoil with 65161 and pelican suitcase, I embarked on a foil drive assist project thanks to the great inspirations of the DIY forum.
First tests on a gong hipe 5.5 110L, and a 6S 20A lipo, it works but you need the help of waves or wind to fly (67kg, big gong fluid xxlt front wing). Looking a bit at the FB page of the commercial foil drive assist, I saw crazy people using 15L boards, and I said to myself why not, and I pulled out my old kite foil board (125CM long, 16.9L ), and I managed to take off en efoil it with only one 6S lipo 20A, one simple fly color 150 A ESC, a simple 3D printed propeller, and it was a lot of fun water to learn to pump. (impossible on gong hipe 5.5 110L, too big and heavy).
Next test in the waves with this mini board for surfing waves with 17l below, it will be a lot more comfortable than with 110L.
I am building a second foil drive assist box in 2x4S 8A and flipsky mini 6.7 ESC in a lighter and smaller box.
I think I have found a simple and low cost way to make your DIY foil drive assist, without having to struggle to make your lithium ion battery.