By parallel I assume you mean the two batteries are connected by positive to positive and negative to negative, then you can have the solar connected to the positive of one battery and the negative of the other battery. Also assuming the batteries are both the same amp.
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Glen
A diesel Nissan Pathfinder towing a Coromal Element 542.
Probably a 20 A DC fuse in line, should only need to connect the regulator output to one battery as they are in parallel. Just make sure pos and neg are correct. Be careful, it may only be ELV (12 Volts) but a deadshort can weld the battery terminals and create a big bang.... and thats no theory.. (pun intended)
Safe travels
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P B Crockart EX RAAF Electrician,
Aircraft Avionics tech. Senior high school teacher.
