I guess the folks to ask would be Vexilar customer service. They have live people answering the phone, or at least they did last time I called.
I think it would just spin the disk in the Vex a little faster is all. Kind of like using a 12volt battery to start a 6 volt car. You’ve done that, right? Starter spins faster and it works great but you need a reducer to protect the rest of electronics in the car from frying. I’d say you’d be better using the conversion device like the Milwaukee power source. Slayer came up with this and as much as I hate to stoke his ego, it’s brilliant. You have to make your own cord using a barrell plug and alligator clips or similar. I measured just under 13 volts with my Harbor Freight voltmeter.