It is recommended that you use the Engel Posi-fit connection for connection to a 24 volt system. This fitting is supplied with your 12 volt lead as standard, simply unscrew your cigar lighter fitting and this will expose the pos-fit connection two pins with a keyway to prevent incorrect polarity damage, and also has a screw on flange to prevent the fitting vibrating out. This is the best fitting for all your off road uses. Please refer to the “Posi-fit connection” under fridge accessories. Part Number # ASPAN, APAN or BPAN.