I run a Benchmark AD2K+, V-3, R-44 and an MT all off of the Tekkeon double battery pack.
All run at 12volts, the MT2 off the usb port. Get 6 hours with this setup. MT2 fully charged to start.
Thought the V-3 would be a problem but Grace told me anywhere from 6-14 volts would work fine.
Page shoepsnbox for a custom cable, he made mine.