wiring a regulator/rectifier on auxillary outboard
I have a 16ft fiberglass bay boat, with a two stroke 50hp Yamaha tiller. It has electric start and a 6amp charging system. The charging rate is just adequate for my needs, but the engine is not conductive to prolonged trolling. To address this I am installing a two stroke, manual start, 8hp Yamaha as an auxiliary for trolling purposes. It has a charging circuit(6amp according to the manual) as is evident by the two green wires coming from under the flywheel. I have installed the correct regulator/rectifier. My question relates to the wiring for the battery. I have only one battery, and no room for another.
Do I have to run the charging wires red to pos, black to neg, directly to the battery terminals, or can I just run the two wires to the main engine battery cables under the 50hp cowling?
I understand that I cannot run the 8hp with the battery disconnected, as damage to the regulator will result. But, could I safely run either or both engines if the charging circuits are hooked up either way as previously stated? Any other suggestions or ideas would be appreciated as well.