Industrial environment installed wet-cell storage batteries in a series configuration with a nominal 540VDC. Doesn't artical 480.7 require a "split string" connection to seperate the batteries to keep the battery group nominal voltage below 250VDC? Manufacturer isn't addressing this article requirement and says series connection is acceptable. Battery disconnect has a diagram on the door which shows configuraiton for both series and split connection.
View attachment 9416
Section 480.7 appears to apply to field constructed battery banks rather than manufactured assemblies, so I am not sure it applies to your situation.
If the internal design meets the separation requirements, then there is no problem with how the + and - leads are brought out to the load.
The two diagrams shown on the sticker seem to be conveying the important requirement that all three poles of the switch must be in series with the current path to safely open under load and withstand the applied DC voltage.
Whether you connect anything external to the middle pole of the disconnect seems to be almost irrelevant if there are only two terminals on the battery bank itself.