I have twin merc 7.4 with about 800 hrs and notice my system output is ok during the day, not as high as i would like it to be, but when running at night, all the loads with the lights on will pull system output down to about 12v. I have called a very reputable electrical rebuild company in the area and discussed this issue with them. They said its common for voltage regulators to get "relaxed" and not increase the "field" when load is applyed. My question is this, is it better "more cost effective" to buy new or just overhaul what i have. They said they check out everything and I have used them in the past for automotive alts with very good luck. Has anyone been down this road?? I don't know what size (amps) i have but may want to increase amp output to charge my house bank, which i plan to add more batteries for an inverter system in the future.

Have your alternator rebuilt with added amperage

i will check with them for pricing, they do have the external regulator on the back. does anyone know the stock output? maybe part # for maybe 100amp or higher??

better to rebuild,if you have a reputable shop near...there is nothing worse than trying to install an alternator with a slightly different bracket set-up...usually on sunday morning

better to rebuild,if you have a reputable shop near...there is nothing worse than trying to install an alternator with a slightly different bracket set-up...usually on sunday morning...jmo

http://www.dbelectrical.com/c-3426-marine.aspx



I had one go this weekend,a member recommended this place.Mercury was $300.00 they were $79.00 new with a one year warranty.Will let you know how it is when I get it,if you type in the Mercury part number in the search it will come up to the replacement.They are knock offs but for that price I can buy almost five of them.

Yep, rebuild. Same with starters. Better to have a local guy with his good word on the line than a rebuild factory in Mexico pumping them out by the thousands.

Put a meter on your batteries to make sure that your readings at the dash are correct! Would suck to replace them and find out you have a different issue....

also load test your betteries. Alternators don't put out many amps at idle/low RPM's. So if you are running lights, stereo.... they can draw lower especially if the battery is not up to par.

batteries are new, i have used the dbelectrical for atv starter several times and had good luck with them. I have checked voltage at the battery with meter, it comes and goes. one time it will be a solid 14.3 and others 12.9-13.2 Its time to have them looked at.