Looked - again - all around the battery box/rack from under the step and from underneath, and the only other thing I see is where the battery negative lines mount to the chassis. No type of device at all within reasonable distance of the batteries.
Weather here has been unfavorable, crawling around on wet concrete isn't my favorite pass time.
I will hopefully have time in the next day or 2 to contact Thor as bevedfelker suggested.
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