Alternator diagrams

[ndutton]

I stumbled across a pretty good alternator treatment including connection diagrams for a variety of styles.

http://www.arcomarine.com/xhtml/Tech%20Marine%20Alternator%20tips.pdf

[jpian0923]

I don't feel like thinking right now, so, is my Delco Remy 10Si (po install) up to snuff?

p.s. I'm vigilant about sniff testing engine compartment before starting engine.

[ndutton]

I don't feel like thinking right now, so, is my Delco Remy 10Si (po install) up to snuff?

Yes but only if it has the visible screen on the back.

[jpian0923]

Doesn't. It's a $50 alternator from O'Reilly auto parts.

[ndutton]

Then it's a pure automotive alternator and not ignition protected, sorry. The screen's function is the aforementioned ignition protection.

[jpian0923]

It's probably been in there for years, with no problems. I'll have to stay vigilant about leaking fuel. I am though. From gas tank to manifold intake I've rebuilt or replaced everything.

All I can smell is burnt oil (which I like).

[ndutton]

Did he say wahzoo?

Besides safety, my concern for you is the chance that some insurance actuary gets a bug up his wahzoo or Heaven forbid you have a loss that is denied coverage after the fact because of it. Sometimes we have to protect ourselves against our paid protectors.

Note that starters are required to have the same protection.

[jpian0923]

Appreciate the concern. Ok, what alternator would you recommend to replace what I have? (if you have the time)

I'm a day sailor with 2 group 24 DP batteries and an AC inverter running some 120v Christmas lights around the length of the lifeline, and about 36 feet of 120v white rope lighting around the inside of the cabin. Some nights we have movie night on the boat and run a laptop, VGA monitor, 2 companion speakers and a 2 terabyte external hard drive. Engine at WOT is at 1900 rpm, at cruise, 1500.

I want to be safe, secure and responsible.

[ndutton]

Bruddah, you've asked a real hot-button question. Ask three sailors and you'll get four answers.

Here's what I think:

1. A general rule of thumb is a 4:1 ratio of battery capacity to alternator size.
2. From your description your needs exceed the norm, I'd go as big as space allows both in batteries and alternator.
3. I feel larger alternators consistently run at a lower percentage of their capacity than the smaller ones. This translates into easier operation. Note that alternator size has little to do with load on the engine. It's the battery bank's need that determines load.
4. What really matters is your assessment, not mine. Are you happy with the performance of your O'Reilly Special? If so, why not get the same thing except with the required ignition protection?

[jpian0923]

So far it's fine. With engine off I can run the inverter fully loaded for quite awhile. If the inverter warns me, I run the engine for awhile and all is well.

But, like I said, I'm just a day sailor (actually a night sailor) right now. That might change. I want to be prepared.

Would it make sense to get the Moyer 120 amp or 55 amp, or stay with what I got? I want to do what's right for the boat. Money no matter.

[ndutton]

Trick question

Would it make sense to get the Moyer 120 amp or 55 amp, or stay with what I got?

Dunno what you've got but I will say this: when it comes to alternators I think bigger is better.

[jpian0923]

Thanks Neil.

[edwardc]

Why can't Jim just get the screen (and any other needed protection) added by an alternator shop? If his alt is in good shape, and big enough for his needs, this would seem to be the most economical and functional route.

[ndutton]

Very possible Ed,

I'm not certain the screen is all that's done to meet the standard but you're right, an alternator shop knowledgeable in marine installations could say for sure.

Jim, I know it's a drive for you but Lewco Electric on 16th Street in Costa Mesa has been the go-to shop in Newport Beach for at least 4 decades. I had them dyno test my 10si alternator (free) and add a tachometer tap ($20).

The property they occupy has quite a history in local boatbuilding and as an added bonus they're about 5 blocks from Minney's.

[jpian0923]

I love Newport Beach. One of my favorite places on earth. I like taking the car ferry from Balboa Island to Harbor Island. It's a great "first date" location!

For now, things are working well for me (using a car alternator). When I upgrade, I'd probably go bigger, and go marine grade. If only for the piece of mind...I'm assuming marine grade means better (I'm sure it does) quality.

I'm sure people like to knock products labelled "marine" and "boat" but there is something to be said for "tinned" wire and "gold plated" hardware.

Thanks guys, very helpfull.

p.s. I did fully test my setup tonight. Alternator got hot while running "everything" but not hot enough to burn my fingers.