Hello, I have a single 1997 502 MPI and it says 65 AMP on the alternator (serpentine belt). I have added a Inverter and some T-145 golf cart batteries and would like more output from my alternator. I know that I can spend 1-2 grand on a Bomar, Etc. Are there any budget upgrades? Can mine be "rewound" for more output or is there a different one that I can pick up used with more output? Do I need a "marine" unit or can I use one for a car? Suggestions?

NEVER use an automotive alternator. Marine units by design have screening to prevent an arc explosion for occuring

You can get a one wire 100 amp marine ALT. I got one and then later installed a sense and excite leads to it because it was boiling bats.

Issues you run into is the feeder cable needs to be increased in size. The one wire does not work very well with the standard Merc wiring, hence why I got the plug for sense and excite.

I would suggest not even doing it, just not worth the trouble. Maybe I did something wrong, but personally, don't think so. Used ALT for one season and removed, and mine is V belt type, and if you want to replace the V with serpentine, I'll sell it to you for $50 plus shipping. Been sitting on the shelf for maybe 5 years now

I just had a 45 amp converted to a 85 amp at the local alternator rebuild shop. Cost $85. He told me that he can make them 100 amp, but they won't charge at idle. This was a marine alt.