[MetroMPG]

Thanks for the idea.

One reason I thought of using the "merry-go-round" relay approach is that it's a more efficient use of the panel. I assumed there would be greater losses going through a DC-DC setup.

EDIT: also, I like the idea of hitting 12v pairs with higher current every N minutes, rather than 1/4 (or less) of the current at a constant 48+ volts nominal across the entire pack. The higher current will mix the electrolyte better, and may be more effective against preventing sulfation (an EE who is an EV owner mentioned that to me).