I am new here and I know this topic has been around before but I haven't found a good answer to what I am looking for. I recently purchased a boat with a 4.3L Mercruiser with 100A alternator, it also has a Honda BFP 8 Kicker with a 12A alternator. Both motors have their own regulator/rectifier. The wiring is in shambles so I am going to be redoing it anyway. Right now both motors are connected to one starting/house battery. I do not think this is right, especially if I run both motors at the same time. I am worried about output voltages being different and one back feeding into the other, or one alternator puking and there some how being a back feed. An example might be if I do not use the kicker very often and want to run it between two lakes where there is a no wake zone just to keep it lubricated and idling the main in neutral. Or another might be if the kicker can't keep up with charging the electronics on board (4 downriggers, 2 chartplotters, etc.), and I want to start the main to charge the battery(s). Anyway what are some thoughts on how to wire the two alternators I would also prefer to go to 2 batteries. I have looked at 2 alternator isolators but don't know if they work with two different sized alternators, and the alternator on the kicker does not look like it can be brought back separately. I have room for 2 batteries but not for 3. I also have 3 independent batteries in series in the bow for my trolling motor, I lock the kicker straight and use the trolling motor for turning, and also the trolling motor independently. I am an industrial electrician but don't work a lot with DC systems. I understand them but this one has me stumped because they are two different sizes. Thoughts are appreciated. Thanks.
) and use 4 electric downriggers (also FF, wash down pump, live well, etc, etc) so I want the Honda to turn on the Pro Mariner as well.