View Full Version : Higher output alternator needed

07-05-2007, 08:08 PM
When I last looked into getting my '91 PS 190's alternator upgraded, the local alternator shop said mine ( OEM 55 amp Prestolite), was not upgradeable (because it was a 'Delco style'). He did bench test it at 14 volts, 50 amps, so it is doing what it can.

He recommended a new Delco Marine 100 amp single wire for about $200. Figuring I could get one much cheaper on line, I found hi output alternators, but it seemed the RPM had to be pretty high to get the 'hi amps'!

1) Can anyone confirm the stock 55 amp Prestolite cannot be upgraded?
2) Can anyone recommend a high output amp that puts out pretty good at idle and most of it's potential around the 1500 RPM range?
3) Any advice on max amp output I should go for? I read that for my 7/32" wide belt, 91 amps was maximum.
I'd feel OK stretching that to 100 amps, I think.

I have two stereo amps (120w & 100w rms) and a single battery. I do NOT want to give up the space under the seat or add the weight and expense of a second battery. Occasionally, my boat will turn over a bit slower than normal while out skiing (stereo is used when engine is running 95% of time). This was a concern, but now that a new stereo head unit 'beeps' when voltage drops, it is annoying and I just turn stereo off to stop the annoying beeping. Radio 'beeps' well before starting ability is lessened.

I think I would be fine if my charge (recovery) rate was higher than 50 amps. Any specific alternator recommendations and where to find them would be great!

PS. my OEM alternator has a 2" thick mounting foot.

07-05-2007, 10:16 PM
This looks too good to be true. New Delco 100 amp marine alternator $74.95


TX.X-30 fan
07-06-2007, 09:32 AM
My suggestion would be to do it right the first time and never worry about being stranded. 2nd battery(AGM), ISOLATER, ALT.

Try Jackrabbit Marine they have complete kits for most all marine applications.