None of that changes the wire sizes I'm seeing connected to the batteries.
In my limited electrical experience wire sizes are determined by amps, not volts...AC or DC.
The wires I see aren't even sufficient for grounds.
BTW, what are all the yellow packets under the batteries for? Dripping acid?
Those battery strings are modern day examples, but MUCH smaller than the types in the central offices where I did my work in the early 80s. I suspect the bags under the batteries are present to neutralize dripping acid. Wire sizes to individual batteries only have to carry the current that battery can produce, not what a whole shelf of batteries can source. The common bus bar must be able to carry the current sourced by the collective shelf of batteries.