[wallyman424]

So I have a 2005 2900 coronet with twin 8.1 crusaders. The boat has internally regulated alternators. Port motor charges Engine battery bank and STBD charges house bank. All batteries are brand new.

The house bank charges fine, motors on, charges to ~14V
The engine bank charges to only 11.8V, the battery bank rests at 11.2-11.4V.

First thing the guys did was send the Port alternator to a repair shop, they dynod it, repaired the rectifier and sent it back saying it was fixed. Alternator was reinstalled and the same problem occurred. Then the guys swapped the Port and Stbd alternators to see if the problem followed, and oddly the problem stayed on the same side. Even weirder they say if only one engine is running, everything works fine. Meaning if the Port engine is running alone, the engine battery bank is charging properly. When you start the stbd motor the engine bank voltage drops.

They yard folks are going to look into it more in depth later this week. But do you guys have any ideas? Im stumped.