32v alternators on both DD 12V71 not charging

[Aussie Mike]

I have 1986 70' Hat MY berthed on Magnetic Island in far north Queensland (AUST) and am preparing to do an extended cruise to Indonesia to our north soon.
Both Delco Remy 32V alternators on my 12V71's are not charging the crank batteries unfortunately.
Would it just be the regulators or something else?
In Australia, nobody stocks 32v gear, so I am looking some ideas or to source 2nd hand alternators or other options?
Any help really appreciated. Thanks

 

[Teddyjensen]

If you put a multi meter on both and confirmed neither have output, id say both failed, rare to have them go at the same time, they are independent systems

 

[scottinsydney]

Mike

See this link from 2020.......

2020 Alternator Posts

You can send to my Florida address and we will freight the part to you on Magnetic Island.

Scott

 

[Aussie Mike]

Thanks Scott.
The link in the 2020 posts didn't work but thanks for trying.

 

[jmooney]

I recall a thread where it was mentioned that the fuel pressure switch controlled the alternator charging. Our boat does not have this . I also don’t know if this is true , but it would explain both alternators failing at the same time.

 

[scottinsydney]

I thought the fuel pressure switch controlled the hour meter? Mine stopped working long ago and also incidently at the same time as each other. So I installed a couple of new hour meters and mow add the total of the old hour meter to the total of the new hour meter.

After 4000 hours and 44 years it realy doesn't matter any more.

 

[jmooney]

It does control the hour meters . And I thought that was all it controlled, until a thread here mentioned alternator control, although it could have been boats older than ours.

 

[Briankinley2004]

Did you run the engines above 1000 RPM to excite the alternator fields before testing them? Most of them don't begin charging until you rev the engines up

 

[Captain Ralph]

We use a diode battery isolator/combiner.
Works great, self exciting alternators hate them.
The alternator senses no battery level, no feedback and can not excite itself at idle or low RPM.

BrianKinley2004 types the most helpful text on this whole thread, when the engine gets warmed up, rev them up to 800-1000 RPM for a second and watch your volt meters.

To get our alternators on line quicker, I ran a lead from a fuel pressure switch to the exciter, near instant feedback. Instant charging when needed.

And lastly, your alternators may not charge if your batteries don't need a charge.
Most folk do not turn their chargers off when running the engines.
Most chargers put out more voltage than an idling engine.
If your engines start rite up, there may not have been much drain on the batteries.

 

[Captain Ralph]

Please post a picture of your alternator.
You should have the bomb proof Delco 30SI alternator. Cheap to fix.

 

[Aussie Mike]

Thank you all for the comments and advice.
I didn't know about running over 1000 rpm to excite them..... I have not done that and will check it out.
By the way, what is the exciter and how does it work ?
How exactly does the diode battery isolator/combiner connect up ?

I did find a new (been in a storage container) Delco Remy 30SI 32v from the UK and the delivered price was around AUD600 which I thought was not too bad.

 

[Captain Ralph]

The diode isolator only lets positive voltage travel one way. From the alternator to the battery.
The beauty of this is you can charge two or more batteries from a single alternator and the batteries are isolated from each other.
On our 32V boat, we use this gizmo with two alternator inputs and three battery outputs. This allows either or both engines to charge up to three battery banks. And these banks will not draw from each other.
Connections are simple, somewhere along that heavy red cable from your alternator to your battery, one of these are installed.

Ah, but nothing is perfect;
Self exciting alternators do not see the battery nor get any feedback/exciting levels. This is where bumping up the engine RPM may help. The alternator makes enough internal noise to excite itself and starts charging. Without feedback, it charges to its regulators mean voltage level.
There is a voltage drop across these diodes, usually around 0.5DCv. Cheap ones may be near 0.8DCv. Mostly not a problem on a boat with battery chargers topping off the batteries every night.
These issues are correctable but require some more gizmos and swamp engineering, also again as on our boat.

Delco 30SI 32v in my area run from $300 to $650. Pending new or rebuilt.
These use an internal regulator and are bomb proof.
I fear they are also the last supported 32v alternator available.


On your next visit to the boat, turn the chargers off for a while.
Let the batteries cool off and loose a little top charge.
Take note of your volt meter and then crank them up. Warm them up a bit before bumping the throttles up to around 1000RPM for a few seconds.
Watch your volt meters, higher than before starting?

 

[scottinsydney]

Hello Capt' Ralph,

Aussie Mike and I have similar boats here in Oz. So alternators are of interest.
About 7 years ago I replaced the port alternator. No further issues.

Would I be correct in saying that the existing 32v alternator windings / bearings could be repaired by an auto electrician?

Would I also be correct in saying that if I purchase a couple of these 32v regulators as spares that they work with the two existing alternators? How to check alternators to see if they are 30Si?

I am wishing to have a fall back position if the 32v side of things are discontinued.

 

[Aussie Mike]

Many thanks Capt Ralph. Great information and very helpful.

 

[Captain Ralph]

30SI's are easy to identify with that flat plate across the back.

These are brush-less alternators. Just two bearings to mechanically wear out.
32V repair parts are still available in the states.

Other alternators may have or not, contact brushes wearing on the armature shaft.
I know the old shot-gun alternator's, 32v parts are hard to find in the states.

I remember some exotic alternators getting re-wound years ago. Not sure if these shops are still around that will go this far for a repair/rebuild.

 

[Dragonten]

As I recall my boat has fuses in the panel in the engine room and I think two are for the alternators. One of mine was blown and affected charging. Did you check the fuse panel?

 

[Captain Ralph]

I forgot Hatt did that. Yes, fuses in the DCv power boxes.

I'm not really a Hatt owner. I act like one on T V.

I still push my ole Bertram.

Bertrams don't AGC fuse everything buried in boxes.

 

[Captain Ralph]

Oh, I just remembered, That's a ANL fuse from the alternators in that darn black box.

 

[Dragonten]

Yes and I carry extras on board just in case.