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-   -   Cruising Without Alternator (Temporarily) (https://www.cruisersforum.com/forums/f14/cruising-without-alternator-temporarily-219123.html)

Dockhead 07-06-2019 08:00

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by a64pilot (Post 2903937)
Where does this it’s not healthy to operate a Diesel under 70% load come from?
Which “expert” is spouting this? I ask as almost all Diesels are operated well under 70% load, and the longest lasting ones are operated well below that number.
Dockhead’s engine being a 100 HP makes the Math easy, at 2000 RPM, an RPM many of us operate at, its at 15% load.
You need enough load to fully warm it up is all, and an occasional blowing it out isn’t bad for it, but running the snot out of it continuously is.

Aircraft Piston engines are the only ones I know of that are operated at 75% power often and usually don’t last 2000 hours, and they aren’t junk motors made from inferior parts, they wear out so fast because they are run so hard.

Engines like DD’s run very conservatively can last, well almost forever, run them hard and they don’t, they have been around forever, that has been known forever.


Yes, and those aircraft engines are very low specific power engines compared to car or boat engines -- the Continental O-300 in the Cessna 172 produces 26kW/l compared to 80kW/l from my Yanmar. Again, you can't really talk about % of maximum power output -- this is pretty meaningless -- you need to talk about power produced per liter of air flowed, to get a good idea of the real loads on the engine.



That diesel engines last longer when run at lower loads we know this also from power boats. Those that are run flat out (70% of maximum, more or less) last MUCH less long, than other use cases, often less than 1000 hours. And the same engines are rated differently for different power outputs, and you can be sure, that the higher the power output, the less hours they are rated to last.



Sailboat engines run at 10% or 15% of maximum -- which is typical -- last pretty much until they rust apart or get overheated or get killed by some other operator error.



All machines last longer, if you subject them to smaller forces. This is in the nature of mechanical things. The lower the power, the longer your diesel engine will last, provided only you don't run at such a low power output that the cylinders don't get warm enough to seal the rings and completely burn the fuel.


Bottom line -- there is no problem running your main engine to generate power, with a reasonable size alternator and a lithium bank which doesn't require an extended finish charge at very low C value. With lithium batts and my 100hp Yanmar, even my existing 2.5kW alternator would be enough load, if geared right and used at a low enough RPM. Get one of those Humvee alternators on a serpentine belt or a PTO and you've got no issue whatsoever, and this is a good way to eliminate one whole diesel engine on the boat, for considerable saving of cost and weight.

Rumpi 07-06-2019 09:51

Re: Cruising Without Alternator (Temporarily)
 
Theway, now that we have established brush failure it's clear it needs to be taken of and opened. If you don't want to do it yourself it's fine, but be asured it's not difficult. Any local shop can do it, no need to wait till Singapore. But if Singapore it is then my advice is: charge the house batteries regularly with the generator and once a day switch the battery combiner on for an hour or so every day to maintain the starter by solar.
If you start the engine, next time you charge by generator switch the combiner on.

Now back to diesels and generators. Please gents understand that the nameplate ratings on sailboat engines are "pleasure duty" ratings. That means no full power for hours, not even 80% power for hours. So yes by ISO approved magic the engine has 100HP. Now derate that for continuous duty generator or prime mover rating and see what you get. Motoring for hours at set RPM as cruisers often do we need to work with the appropiate ratings. Yes modern motors are much more elastic, especially turbo and common rail ones so 70% of continuous duty is probably to much, I admit that.

BTW Dockhead please be so kind and look at that graph you posted. On the left side you have a kW and on the right side a HP scale. So at 2000RPM your engine can do 60HP max. and the propeller loading is 20HP. Given your engine is about 105HP max it means you are at 19% loading from pleasure duty maximum and probably about 50% loading of continuous duty rating.
Wich probablty puts you right on the power/fuel consumption map sweet spot oval. Operating outside that range brings increased consumption and some other problems.

Dockhead 07-06-2019 11:31

Re: Cruising Without Alternator (Temporarily)
 
1 Attachment(s)
Quote:

Originally Posted by Rumpi (Post 2904096)
. ..

Now back to diesels and generators. Please gents understand that the nameplate ratings on sailboat engines are "pleasure duty" ratings. That means no full power for hours, not even 80% power for hours. So yes by ISO approved magic the engine has 100HP. Now derate that for continuous duty generator or prime mover rating and see what you get. Motoring for hours at set RPM as cruisers often do we need to work with the appropiate ratings. Yes modern motors are much more elastic, especially turbo and common rail ones so 70% of continuous duty is probably to much, I admit that.

BTW Dockhead please be so kind and look at that graph you posted. On the left side you have a kW and on the right side a HP scale. So at 2000RPM your engine can do 60HP max. and the propeller loading is 20HP. Given your engine is about 105HP max it means you are at 19% loading from pleasure duty maximum and probably about 50% loading of continuous duty rating.
Wich probablty puts you right on the power/fuel consumption map sweet spot oval. Operating outside that range brings increased consumption and some other problems.


Yes, 20hp not 15hp -- thanks for the correction.


But that's 21.7%, not 50%, of the continuous duty rating of my engine, which is 92 horsepower:


Attachment 193464




You need to forget about % of maximum power as a measure of a healthy load. This is irrelevant. The healthy load will be some percentage of the maximum power AT THAT RPM.


Running the engine at 3500 RPM and taking only 20hp from it might be harmful. At 2000 RPM it is no problem.


That's why wet stacking and bore polishing are issues with constant speed

gensets, but almost never seen with sailboat main engines, even those used for hundreds of hours charging batteries near idle.

wingssail 07-06-2019 11:36

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by Rumpi (Post 2904096)
Theway, now that we have established brush failure

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

theway 07-06-2019 16:43

Cruising Without Alternator (Temporarily)
 
Thanks for the feedback everyone. Iím going to take the alternator off and have it looked at in Mataram on Lombok. Any advice on this process...

Step 1: Unplug, Unbolt.
Step 2: Drop off, Pick up. (Any specific questions or tests I should observe or request done there, certain materials or repairs)
Step 3: Bolt on, Attach wires
Step 4: Test on boat

Does anyone happen to know a specific shop in Mataram? If not I have a friend here on Gili Gede that will help.

Stu Jackson 07-06-2019 16:50

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by theway (Post 2904328)
Thanks for the feedback everyone. I’m going to take the alternator off and have it looked at in Mataram on Lombok. Any advice on this process or just unplug, unbolt, and drop off....

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


Glad to hear you decided to do the reasonable thing.


Think of the alternator shop as your doctor. Do you go into your doctor and just say: "Fix me." Or do you tell him the symptoms and why you are visiting him/her?


Unless it's painfully obvious, one usually can't tell by just looking at the alternator, so the more info you give them, the better they can help you.


Gee, just like a boating forum! :smile::smile::smile:


When I had mine in for repair, they fixed what was wrong inside, then bench tested it and told me the max output in amps - always good to know. Tell them it's on a boat and what the boat rpms are so they can convert the alternator rpms based on the pulley sizes, so measure your crankshaft pulley, too. OTOH, I told them it was on a boat but they just bench tested it for amperage output without asking about the crankshaft pulley size. Could be some standard I don't know about, someone else here might.




Good luck, please let us know what happens.

wingssail 07-06-2019 16:53

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by theway (Post 2904328)
Thanks for the feedback everyone. Iím going to take the alternator off and have it looked at in Mataram on Lombok. Any advice on this process...

Step 1: Unplug, Unbolt.
Step 2: Drop off, Pick up. (Any specific questions or tests I should observe or request done there, certain materials or repairs)
Step 3: Bolt on, Attach wires
Step 4: Test on boat

Does anyone happen to know a specific shop in Mataram? If not I have a friend here on Gili Gede that will help.

Just make sure you put a good wrapping of tape on the end of the output wire which is straight to the battery or you'll get some fireworks when it touches the engine block.

Be sure to specify that they use the exact size wire and number of windings, assuming that it has to be re-wound, or the output will be different.

theway 07-06-2019 17:03

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by Stu Jackson (Post 2904335)
Glad to hear you decided to do the reasonable thing.


Think of the alternator shop as your doctor. Do you go into your doctor and just say: "Fix me." Or do you tell him the symptoms and why you are visiting him/her?


Unless it's painfully obvious, one usually can't tell by just looking at the alternator, so the more info you give them, the better they can help you.

....


Ok, so itís not the kind of thing that is just rebuilt like a water pump, replacIng all of the worn parts and even some that arenít so worn but done anyway because itís opened and available for newer bits.

theway 07-06-2019 17:06

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by wingssail (Post 2904337)
Just make sure you put a good wrapping of tape on the end of the output wire which is straight to the battery or you'll get some fireworks when it touches the engine block.



Be sure to specify that they use the exact size wire and number of windings, assuming that it has to be re-wound, or the output will be different.



Iíll definitely tape up the wire ends.

And same question from above:
So, itís not the kind of thing that is just rebuilt like a water pump, replacIng all of the worn parts and even some that arenít so worn but done so because itís opened and available for newer bits?

Wotname 07-06-2019 17:20

Re: Cruising Without Alternator (Temporarily)
 
^^ there are only a few parts in an alternator, namely bearings, brushes, a diode pack and windings plus an internal regulator (if fitted).

The brushes are a wear item and need to be replaced when they get too short.
The bearings are like all simple bearings, replace if noisy.
The winding rarely fail and the burnt smell is usually obvious!
The diode pack can fail especially if the output has being disconnected while the alternator was producing significant current at the time. The pack is easily checked when the alternator is disassembled.

There is more to know but this is the basics of all alternators.

a64pilot 07-06-2019 17:36

Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by theway (Post 2904341)
Ok, so itís not the kind of thing that is just rebuilt like a water pump, replacIng all of the worn parts and even some that arenít so worn but done anyway because itís opened and available for newer bits.



It usually is, and quite often what your doing is giving them a rebuildable core, you get an already overhauled and tested unit.
Probably not with a Balmar though, and I doubt they can rewind that like Balmar did, with the flat wire and all.

nwdiver 07-06-2019 17:37

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by Rumpi (Post 2903474)
Look theway, the goal is not to get 12V to the blue wire, the goal is to test the alternators internal connections (the brushes) without first dismantling the alternator. For that test to work you need two things, faultless ground on the ground post and 12V on the field excitation post. Since you have an isolator on the red wire and are working upside down in a small space the simplest thing is to bring 12V positive into that space. So take a long enough piece of wire and clamp it to battery positive. The other end you put a spade or ring connector on and wrap in tape so you don't short anything by mistake.

The balmar manual troubleshooting starts with making shure you have good ground otherwise all tests are meningless. They also have a section for testing the blue wire continuity before testing for magnetism. That's because +12V in does not mean you always get +12V out (the cable or connectors may be bad). The test you did means nothing if you don't have good ground or the blue wire itself is bad.

You have measured 13.5V at 1400RPM so that means the alternator is working somewhat. Your problems can be:
1. Faulty ground somewhere, and a pain to diagnose. That is why Balmar wants you to have a cable of sufficient size directly between alternator and battery negative. That way you only have to clean two connections and inspect one wire. This is often ignored by installers who ground the alternator to the engine or some negative bus making your life a misery of chasing wire and cleaning every single connection. The brutal way to solve bad ground is to retrofit (or if present exchange) this cable (see balmar sizing chart). Still leaves you with bad ground in other parts of the instalation.
2. Sticky brushes. The brushes wear and the high humidity bakes the resulting powder. The spring can not press the brushes firmly and you get erratic connection while running (from engine vibration) and sometimes no connection at rest. Simply solved by cleaning or exchanging the brushes but in order to avoid demounting and dismantling the alternator for nothing you test for magnetism first.
3. Bad connections in the wiring harness to the regulator. This is easy to test for.
4. Bad voltage regulator.

Troubleshooting begins by establishing ground, then you have the choice. Balmar sequence is testing regulator, testing wire harness, testing magnetism.

Just another thing: an alternator is only really bad if smoke escapes from it, and even that can be repaired. The fact that it is old and out of production means nothing. Brushes come in standard sizes or can be ground to fit. Diode bridges are cheap and if a specific configuration is unavailable any electrician can convert to external rectification where you can use whatever diodes are available. Bearings are standard sizes also. The only part that is really alternator specific are the brush holders but even those can be adapted. Buying a new alternator is only warranted if you want more output.


This I totally understand.....

Electricity + Smoke = BAD

nwdiver 07-06-2019 17:40

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by Jim Cate (Post 2903627)
I'll be damned! I sure wish that you had told me that when we set out cruising in 1986, for it would have kept me from being unfit for offshore extended cruising for all these years! I'm sooo ashamed.

Seriously, a gen set of any size is a convenience, but far from a necessity for offshore cruvxising of any length.

Jim

I agree.......my gas SCUBA compressor is a necessity, not a gen set ;)

Stu Jackson 07-06-2019 18:20

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by theway (Post 2904341)
Ok, so it’s not the kind of thing that is just rebuilt like a water pump, replacIng all of the worn parts and even some that aren’t so worn but done anyway because it’s opened and available for newer bits.


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.:peace:

RaymondR 07-06-2019 19:05

Re: Cruising Without Alternator (Temporarily)
 
Quote:

Originally Posted by Boatyarddog (Post 2903342)
All gensets would have their own built in charger.
As these portable generators use gasoline and spark, some even there own starters. They provide power for their electrical system.
Battery chargers are built in to these units.
My Honda1000, incorporates a 10 amp charger, and can be paralleled with another Honda.
It's a nessessary item for any offshore extended cruising.
It avoids the issue of Dead Batteries

In my opinion the mains voltage AC genset aboard the smaller cruising sailing yacht should be a thing of the past. Fairly high capacity inverters are cheaply available and a small gas engine driven low voltage auto type alternator makes a far superior battery charger from both utility and safety viewpoints. Different matter with a floating gin palace with their high refrigeration,water making and air conditioning needs.


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