Cruising Without Alternator (Temporarily)

[theway]

Originally Posted by Stu Jackson

Pretty much, but what wotname and a64 said. It could be simple and usually the harder to fix parts are the parts that thankfully usually don't fail.


Again, another analogy: you're asking the doctor what's wrong before he even begins the examination.


Do you have Calder's Boatowners Manual? Good description of what goes on inside. You could probably find the same info by doing a Google on "How do alternators work?" wikipedia could help too, and I'll bet there are YouTube videos on alternator repair.


While you may learn how to do it, theoretically via la internet, in your case, and in my own personal experience, I'd have "the pros" do it. Not really something I'd think you'd want to learn right now. But some folks choose to do so and I applaud them for that.


Just my impression from this thread and discussions that you, personally, would be wise to have them do it. Heck, they even might let you look over their shoulder while they do it. My alternator repair shop back in California, Oakland your old stomping grounds!!!, taught me a lot although I wasn't there when they cracked my case.


Good luck happy learning.

Cool, that all makes sense and yeah I carry the same sentiment - Let someone else do it and hopefully they’ll let me watch. And after watching enough times maybe attempt, but only with a pro nearby to help if need be.

I do have the Calder book and plan to study it more before I go.

And thanks again all, I’ll update as things progress. Removal tomorrow and up to Mataram on Monday.

[Rumpi]

Originally Posted by wingssail

How do we know it is brushes? Could it not be a field winding failure?

Yes it could, but logic says to first supect the part that moves and wears out. Without smoke escaping one usually does not suspect the windings beforehand, but they get tested anyway when the case is open. I am curious to hear what it was after all.

Theway the one thing to watch out when rebuilding is the bearings. Now if they need replacing or you want to do it anyway be sure to buy some where you recognize the brand.
Basicly there are 3 steps: repair, refurbish, remanufacture. Repair means restoring function. Refurbish usually means renew all wear parts. Remanufacture means bringing everything back to factory spec, including the paint. An alternator is such a simple machine that repair and refurbish is hard to distinguish.

[Wotname]

Originally Posted by Rumpi

Yes it could, but logic says to first supect the part that moves and wears out. Without smoke escaping one usually does not suspect the windings beforehand, but they get tested anyway when the case is open. I am curious to hear what it was after all.
..................

Exactly

Alternator brushes last a very long time (usually many thousand hours) and field windings outlast brushes by several orders of magnitude. They usually only fail due to abuse (high loads and compromised cooling).

At least that has been my experience - YMMV!

[masonc]

Isn it externally regulated or internally?

[Rumpi]

Externally regulated but with internal rectification. Probable identification as Balmar series 9.

Theway, can you take some photos once it is out?

[masonc]

Has he tried exciting it

[theway]

I got the alternator off and had it looked at. He showed me the brushes and indicated that was the problem (they looked really short/worn).

I watched him go through a serious of tests with the meter connecting all different bits and seeing the needle jump. 20 minutes after he started it was done.

Now the question, Could the brushes be a reason I wasn’t getting magnetism? Or is there something else I should have him test/look at?

(I’ll post some pics soon)

[Rumpi]

The brushes carry the current from the voltage regulator to the rotor winding via the sliprings. If the brushes are stuck or worn there is no contact between brush and slipring, and no current reaches the rotor coil. No current = no magnetic field = no output. Solution is to replace the brushes. So has he replaced the brushes and is the alternator working?

I supose he did all the usual tests and found everything ok or he would have pointed at the defect and waved his hands and head in dismay. Beside worn brushes the other common defect is grooved sliprings.

[theway]

Originally Posted by Rumpi

The brushes carry the current from the voltage regulator to the rotor winding via the sliprings. If the brushes are stuck or worn there is no contact between brush and slipring, and no current reaches the rotor coil. No current = no magnetic field = no output. Solution is to replace the brushes. So has he replaced the brushes and is the alternator working?

I supose he did all the usual tests and found everything ok or he would have pointed at the defect and waved his hands and head in dismay. Beside worn brushes the other common defect is grooved sliprings.

Hey Rumpi... yup, he showed me the brushes and i could see how short they were, I gave the nod to fix and they were replaced. And yup he did a few test, one test he did a little out of my sight with a battery on the floor, guessing that might have tested magnetism... after that he gave the nod that it was good.

Thanks for the explanation, I was googling but nowhere explains that link between brushes and magnetism.

I’ll be a couple nights here in Mataram and then I’ll install Thursday or Friday.

[theway]

Here’s some photos.

Before and after I cleaned it. As I mentioned I had an exhaust leak last year. I’ve cleaned up most things....

Model plate...

And some pics from the shop... Looks pretty old, but he didn’t call attention to anything but the brushes.

[lateral]

If you want a cheap drop in high amp spare alt that will fit a 3GM30f a bosch from a 944 porsche will fit if you grind a couple of mm of the rear foot and pack with acouple of washers on the front. Two min job.
Has the advantage of being able to swap out brushes in 5mins as there external and being able to externally regulate as the brush set and regulator are one piece. Non regulated brush sets are available.
ALSO comes with a cowl to supply external cool air.
MUST use gates green stripe belts if single.
$50-100 on ebay.
Pm me if anyone wants details.
https://www.ebay.com/itm/PORSCHE-944...MAAOSweX5cKBAn

I did fab up a custom tensioner as the hitachi one wont fit.

[RaymondR]

Easily detected fault with a simple test.

Like most of us I did not know a lot about alternators before I took up boating in remote places. I have the alternator subject pretty well covered now and am working on refrigeration.

[theway]

Originally Posted by Rumpi

I have to point out the obvious: alternators don't die from sitting around. If it was fine 4 months ago it's fine now. Your problem is corrosion.

Can we back up to this for the sake of exploitation? Because this still seems like one of the most notable and valuable points. If I reinstall the alternator and everything is fine, and the problem was fixed by new brushes... How does that explain why it worked 4 months ago and not now?

Any guesses or logical conclusions based on experience?

(The engine wasn’t running and the brushes wouldn’t just wear themselves down)

[Fore and Aft]

Off subject a little bit but I had a 40 amp Victron battery charger mounted near my Smokey generator. One day it stopped working when I opened it up it was covered in carbon from the exhaust. I blew it down then cleaned it with WD40, moved its location and it has worked fine ever since.
Cheers

[RaymondR]

Originally Posted by theway

Can we back up to this for the sake of exploitation? Because this still seems like one of the most notable and valuable points. If I reinstall the alternator and everything is fine, and the problem was fixed by new brushes... How does that explain why it worked 4 months ago and not now?

Any guesses or logical conclusions based on experience?

(The engine wasn’t running and the brushes wouldn’t just wear themselves down)

Worn brushes causing little spring force allowed brushes to become stuck in the brush holders.