[TimV]

Yes. Lithium is the way to go.
I already have a thread running on that forum. But i aim not shure if i can fit a normal crank motor conversion in it. And i want to update the readers of my cars thread what i do now

Hopefully i can discover how the pedals are attached to the frame and then i can make a descision on what i need to use.

On a normal bike you cruze like 20 to 25km/h. With the velomobile, thanks to the aero benefit, you cruze with the same effort at 30 to 35km/h. That is a nice benefit.
Only when you need to climb a hill. The extea weight will work averse and slow you down. Until it is back downhill.

I used to have an 45km/h pedelec with a 350W crank motor. I aim aiming for equal power. Like the 350W or the 500W version.