I have the cure for the lack of an alternator on your test bench. Use something like a shop fan motor, or similar device that can create steady rpm, to belt feed an alternator mounted on a tension pulley. Then wire as necessary and viola, alternator powered battery bank to simulate a running vehicle. Of course you could do some math and get the right pulley sizes, or a variable speed motor, that way you could control the rpm for all the haters that love to try to find some way you cheat in every video.