I have twin 454 mags and i only use two batteries. I have to master switches and can keep each motor on there own battery. The thing is one battery has trouble starting the motor by itself. I want to always have a single bank of two batteries but was wondering if it would hurt anything if both engines are charging to the same bank of batteries. WIll this damage the alternator or batteries?

It causes what is called bucking, over time it will kill the alternators. This was a common practice by the manufacturer of SeaBird boats which were mostly powered by the Merc 470 which had expensive stators built into the harmonic balancers. We had three at our marina, it took us awhile to figure out what was killing them. You need to take the time to find out why one engine is not getting enough juice to fire off, could be as simple as a bad ground or dirty battery connections.

Phil

I agree with MOP on the fact you need to figure out why the one batt has problems IE bad batt, bad alt, bad connection


on the 470 note....the 470 stator /regulator rectifyer system was one of the worst ideas merc ever came up with using a water cooed reg/ rec ect made it an overly expencive, inferior system and the best thing anyone ever did was come up with the delco single wire retro fit for it


after 25 yrs in this bus I could write a book on the pros and cons of the 470/485 merc motors

phil by the way the stator was behind the balancer the magnets where built into the balancer( glued)

Joe