[dad911]

You could measure with a voltmeter and see which connector is positive.

If it was me, I'd follow the wire and see if it looks like a factory connection. If not, I would remove it. I do not trust PO wiring.....

It does however look like a tender connector: https://www.amazon.com/Battery-Tender-081-0148-25-Disconnect-Extension/dp/B000FW2MWW/ref=pd_bxgy_2/140-0255688-4255110?_encoding=UTF8&pd_rd_i=B000FW2MWW&pd_rd_r=233d90bb-ff1c-4ee0-aa1f-32bbdb0d1bda&pd_rd_w=Oou36&pd_rd_wg=AtMLL&pf_rd_p=4e3f7fc3-00c8-46a6-a4db-8457e6319578&pf_rd_r=347CF8XY9C5293ZJHXPZ&psc=1&refRID=347CF8XY9C5293ZJHXPZ