Mercruiser 470 charging system

[Loyd Dinneen]

I have twin 470's with I think they are rectifier charging sysyems. The port side charges at 13.5 volts where the starboard side charges at 16.5 to 17.0 volts. It seems to me that is a bit on the high side and can damage my batteries. Does anyone know if there is an adjustment that can be made on the regulator to lower the charging voltage or is this normal for this system?

 

[Bt Doctur]

Non-adjustable , you could try using a Harley Davidson rectifier from one of the big bikes. They have ratings to 30 amps
Other option is to convert to a standard alt system

 

[Loyd Dinneen]

I was looking at a forum on IBoat and a guy there replaced the regulator with a ford solid state regulator #f400 from O'Riallys back in 2009 and it worked fine and was putting out 12.8 volts. It only cost him about 38.00 then. I checked on the age of my marine battery and it is 5 years old which in deep cycles is a bit over it's life span, it still starts the engine fine and seems to hold a charge What I did notice(even though it was dark and using a flashlight) was there was some dampness on top of the battery as though it had been cooking over. I have two new house batteries and I may disconnect the old battery and hook in one of the new ones in and see if I still get the high charge rate. If not I will change out the new batteries to the engines and put the old ones for the house. The house batteries are only charged by the on board charger and a 50 watt solar charger, not hooked into the engine charging system. I only need it to run the fridge thru an inverter and maybe a 12 volt fan.
The alternator conversion is very expensive and I have already spent my limit on this boat and haven't even got it in the water yet. I would at the most buy a new rectifier regulator for 300.00 and that is really a no go. It is double that for the conversion and it is a bear to get at anything in the engine area with the twin 470's, and if you do one you have to do both. If the one regulator stops working the system on the other engine will keep the two batteries charged up anyway because the system is some how tied together.