It IS the battery disconnect. It is a switch we found that i used in the marine industry...not sure why the labeling is ridiculous.
ON-means power on
OFF-means power off.
You need to have it ON to charge the batteries will plugged in.
At some point this year (right around the same time we switched to the progressive dynamics converter), we started wiring the convertor charge line directly to the batteries, so the switch position will not matter on late model 2015.
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