Merc 115efi over-charging battery

[Bigjohn1]

Engine: 2004 Merc 115efi. <br />Problem: Suspect regulator is allowing alternator to over-charge battery.<br /><br />300 hours of flawless running. Only problem has been regulator is allowing between 15.3-15.8 of charging voltage. While this is within factory specs, it is causing me have to add about a pint of water per month to my current wet cell battery. I should not be using this much water in a battery and am about to replace the battery to an AGM. Since you can't add water to a sealed AGM, I am worried this charging rate will simply ruin a $200 battery over time. I have tried<br />"adding load" while running by switching on some additional electrical components but it has had almost no effect on amount of water being boiled out of the battery. Any ideas on what I can do? From what I understand, the voltage regulator is pre-set and non-adjustable.

 

[andy6374]

Re: Merc 115efi over-charging battery

First off what type of battery are you using? An automotive or maintainance free battery won't work for you.<br /><br />As far as the voltage regulator, if you are going to replace it, get a rect./reg in one from CDI/Rapair. They are superior and have a cutoff voltage of 14.3 volts.

 

[Bigjohn1]

Re: Merc 115efi over-charging battery

Thanks Andy - The battery is Interstate deep cycle marine so it is a quality unit (as wet cells go). What does CDI/Repair mean?

 

[Bigjohn1]

Re: Merc 115efi over-charging battery

Ok, now I see CDI/Repair is a outboard parts source. BUT....They don't list a regulator for any mid-range 4-strokes and definitely not a 115efi. Any other ideas?