Feasability of using a truck alternator in a marine setting

[Mike Two Moons]

Hello:
I am wiring a Delco-Remy 55-63A externally regulated alternator (truck) in place of an Ample #4024 130/116A marine alternator whose diodes have failed. I want to arrange a temporary charging capability for the house batteries, until I can obtain something permanent. We are a steel boat.

My starter battery is charged by the stock Yanmar alternator. There are connector switches that can amalgamate the two battery banks.

If the Ample V3 charge controller is functional, I will try to utilize it rather than the Ford F540HD.

My concern is that the Delco alternator has a grounded housing, where as the Ample’s is insulated to negate stray current in the boat.

Questions:
If I can find a way to insulate the Delco from the motor mount/engine block/prop, would I need to incorporate a ground wire to the Delco to draw away any static build-up? It does use the truck chassis for ground when running and I would like to avoid this.

I am considering a) installing the Delco to charge the house batteries and disconnecting it from service by removing the fan belt when the house batteries are fully charged to avoid unnecessary stray current OR b) forgetting the Delco and just run with the Yanmar alternator and charge both battery banks as required – what is my risk doing this.

I am currently in southern Spain and heading for Gibraltar, where I hope the service structure is more robust that where I currently sit.

Thanks for any comments………Mike

[a64pilot]

I think almost all regular marine alternators ground through the frame, I think not is unusual.
I think Mark Grasser will do a isolated ground
I also think that in essence, the difference in marine and truck is wording and cost, a small frame Delco is a small frame Delco.

[boatpoker]

I've run truck alternators on my diesel boats for 25yrs..... no issues.

[UNCIVILIZED]

Lots of folks use truck alternators. The Dashews are big advocates of them in some of their writings.

[model 10]

How could you build an insulated mount? Accessories mounted remote from the engine have too many belt problems. And what is with this "stray current" idea? Where would it be comming from and what does it do?

[Mike Two Moons]

The house alternator is mounted on a steel platform which is part of the engine mounts, which connect to engine and prop.

When the Ample was in place, there is no connectivity between the alternator housing and the mounting bracket. This is good. No worries about the prop disappearing.

When the truck alternator is mounted, there is connectivity with the bracket.

A car and truck use the common ground of the body/chassis to complete the circuits. This is not a wise move for a steel boat.

This is a short term solution, until I can get an insulated alternator back in place. Until then, I was trying to understand if I am creating new problems.

[svHyLyte]

For what its worth, we have been running an off-the-shelf stock 105 Amp "Silver Bullet" truck alternator, controlled by a Balmar ARS-5 regulator, for 15+ years with no difficulties at all.

[Matsubob]

Ummm, only problem is that marine alternators and starters have enclosed brush housings, to avoid bilge fume explosion. From what I understand, if you are running anything else, any insurance that you may be carrying is null and void.
Same thing with automotive carburetors on gasoline engines of the GM variety. The carb is built differently. Technically, there is a workaround for both of these issues, but that is what the law says.
(now watch the fur fly!)

[Elie]

Hummm... Diesel engines don't realy need such protection, reserved for gasoline engines. Diesel fuel quality is that it is not volatile at normal pressure, that is the first argument for having diesel engines in our sailboats.

[model 10]

By inclosed you mean a screen over the back of the unit to prevent flame propagation. My Balmar does not have a screen but my spare Delco Marine does have a screen.

[boatpoker]

Originally Posted by Matsubob

Ummm, only problem is that marine alternators and starters have enclosed brush housings, to avoid bilge fume explosion. From what I understand, if you are running anything else, any insurance that you may be carrying is null and void.
Same thing with automotive carburetors on gasoline engines of the GM variety. The carb is built differently. Technically, there is a workaround for both of these issues, but that is what the law says.
(now watch the fur fly!)

Thought the OP was talking diesel ?

[Pauls]

Trace out the circuitry of the truck alternator. if it has a positive lead output but no negative lead connection (which is normal) then the alternator case grounded on the truck functions to complete the negative side of the circuit. Insulating your mount is the right thing to do. You will need to run a cable from the battery negative to the alternator case to replace the circuit that was provided thru the truck chassis.

By the way, it isn't really a truck alternator. It's just an alternator, that Ford puts on some trucks. It will work fine on your boat.

[Matsubob]

I agree. Diesels have that safety feature. That is sure why I have one!

[a64pilot]

If I were you, I would source a "negative field feed" alternator.
Unless I'm mistaken that is an alternator that does not use the case for ground, you need a separate ground wire for one.
I'd hate to introduce stray current especially in a steel hull.
Mark Grasser is one source, cal him, he may tell you how to convert yours or do the conversion for you.
http://www.markgrasser.com/products.htm#alternators

[captlloyd]

Originally Posted by Mike Two Moons

The house alternator is mounted on a steel platform which is part of the engine mounts, which connect to engine and prop.

When the Ample was in place, there is no connectivity between the alternator housing and the mounting bracket. This is good. No worries about the prop disappearing.

When the truck alternator is mounted, there is connectivity with the bracket.

A car and truck use the common ground of the body/chassis to complete the circuits. This is not a wise move for a steel boat.

This is a short term solution, until I can get an insulated alternator back in place. Until then, I was trying to understand if I am creating new problems.

My engine on my steel boat was isolated at the motor mounts. I also had a flexible coupling at the prop shaft. Theoretically then both the engine and alternator were isolated.