Nominal voltage of the VX1 is 125 Volts. The charger and motor controller can go up to 156 Volts and some VX1 owners are now converting their bikes with Nissan Leaf modules to Lithium. 18 or 19 Leaf modules are the configurations to choose from and it is almost like the battery box of the VX1 was designed to hold them!
By the way, the Vectrix provided Lithium option is rubbish so don't get too exited about that...