Originally Posted by wakemaker01
what is involved in upgrading from a 65 amp alt to a 115amp alt my motor is a mercruiser 350 mag . Will you have to upgrade anything else?
What style belt do you have? If you only have a single v pulley don't go much over 100amps or you will burn up belts pretty quick.
For the alternators you have a couple choices if you want a reasonably priced OEM quality unit. Delco Remy makes the 95 amp unit that is currently standard on most Indmar engines. This should bolt in as it has a 2 inch foot. It also has dual internal fans so you don't have to worry about the fan rubbing on the water intake line if that is run close to the alternator. With the Delco 95 amp there is a plug that you have to buy with it and you have to run a wire to excite the alternator as it is ignition excited vs self excited.
The other ok option is a Prestolite/Leece Neville 90 or 105 amp 8MR unit. The problem with these is according to their output curve they don't turn on until ~1800 shaft rpm. The delco does at 1200. The Delco also has a better curve at low rpm's. Both alternators are probably going to be in the low 200's.
If you have a serpentine belt you have at least one better option. The Balmar 6 series comes in outputs up to 150 amps. It has a great curve and would be a great option if you couple it with Balmar's Max Charge regulator. This system isn't cheap though, probably running in the 700-900 range for the alternator, pulley and regulator.
With all these options, especially the balmar, you need to take a look at your current battery cables and see if they can handle the voltage. If no you risk creating to much heat and melting the cables and I am pretty sure you do not want to blow up your boat.
As for DB electrical, you tell me if you think a 150 amp alternator for a $150 is a quality product. There is almost no doubt it is made up of Chinese components. Also if they are advertising a 150 amp alternator will work with a single v pulley there is something weird going on.
I am sure there is a ton of other things to consider but this post is already too long.