I agree too. We all know the Quark runs just fine at 5s. So:
5s lipo at max charge is 21v (4.2v/cell). The nominal voltage is 18.5v (3.7v/cell).
6s A123 at max charge will be 21.6v (3.6v/cell). The nominal voltage will be 19.8v (3.3v/cell).
I would use 17volts (load) for voltage (6s A123) input on Brian's calc for top speed.
“The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens