Cruising Without Alternator (Temporarily)

[theway]

Originally Posted by Wotname

Converts seconds to hours (i.e. 60*60=3600)

(Thumbs up)

[Wotname]

Originally Posted by theway

Very good points, thanks for the input.

The engine is a Yanmar 3GM30F. I do have the ability to turn off the starter battery completely with a switch. I’ll definitely run some test to make sure nothing is drawing from it and monitor it often.

...

Your engine has decompression levers so the easy way to reduce the electrical load on the starter battery is to use them when starting the engine. You will get a heap more starts from a battery by doing this.

1. decompress all 3 cylinders.
2. spin the engine over using the starter motor for say two seconds.
3. compress one cylinder and as soon as it fires, stop using the starter motor.
4. compress the next cylinder
5. compress the last cylinder

You may have to experiment a bit to get the timing right and the best throttle setting but I have found a throttle setting around the 1200 to 1800 rpm is a good starting point. It will depend a bit on how easy it starts normally.

[theway]

Originally Posted by Wotname

Your engine has decompression levers so the easy way to reduce the electrical load on the starter battery is to use them when starting the engine. You will get a heap more starts from a battery by doing this.

1. decompress all 3 cylinders.
2. spin the engine over using the starter motor for say two seconds.
3. compress one cylinder and as soon as it fires, stop using the starter motor.
4. compress the next cylinder
5. compress the last cylinder

You may have to experiment a bit to get the timing right and the best throttle setting but I have found a throttle setting around the 1200 to 1800 rpm is a good starting point. It will depend a bit on how easy it starts normally.

Sounds like useful information (i don’t exactly understand it all but I’ll look into it). The engine usually starts quick with out much effort, most times just a quick touch of the button. Even after the 4 months I was away.

[Wotname]

Originally Posted by theway

Sounds like useful information (i don’t exactly understand it all but I’ll look into it). The engine usually starts quick with out much effort, most times just a quick touch of the button. Even after the 4 months I was away.

OK, well it sounds like the engine has good compression and starts easily (i.e. quickly).

IMO, it's good to know the alternative ways to start an engine that has decompression levers as the method can be helpful when you have a near flat battery or starter motor issues or wiring issues etc.

[Dockhead]

Originally Posted by theway

Now you’re giving me confidence. The gauge lights are all on a switch and rarely use because I mostly travel by day.

I have started the engine 4-5 times now to diagnosing the problem and the voltage on the starter battery is at 100% about 12.8 on the meter.

I’ll see what my options are maybe delay a few days to see what I can find, if not I’ll carry on.

I do have a gas generator for a charge if it would come to that.

If you have different ways to charge the start battery then you will be OK, but you need to keep a close eye on the voltage because you WILL be using up the start battery charge while running the main engine.



As others have mentioned, alternators are really simple devices and can usually be repaired and almost anywhere. There are auto electric shops in every third world town which can take apart, rewind, and cobble together some kind of solution for almost any alternator problem.


Also a wide variety of alternators can be adapted to fit.


So depending on how much time you have -- this should not be an overwhelming problem.


From a systems design point of view -- this case shows why it is undesirable to run house loads and engine systems off one alternator, usually a car-type alternator which is not designed for bulk power generation in the first place. It is vastly better to have separate alternators for the engine systems, and for house loads, the latter being a heavy duty large frame school bus type alternator which is designed for the duty. That's of little comfort to the OP, but note for the rest of us.

[Rumpi]

Originally Posted by theway

The story is: I left the boat for 4 months and on return it would not charge the batteries. The readings at the regulator are accurate which suggests wiring is fine, so I did the test to see if any magnetism comes from the pulley bolt/nut and got nothing. It seems like a good time to replace it.

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. If you did the magnetism check correctly (ignition on) and don't get any it means your field is not getting current or the alternator can not complete the circuit to ground. You say the readings at the regulator are accurate, can you describe this?

Balmar series 9 are isolated ground so first thing is to check the ground wire. Disconnect, clean, reconnect and check continuity. Ideally the wire should go to the battery negative and be of the same gauge as the positive one. Now check again for magnetism. If no magnetism present connect 12V to the field wire (jumper). If you get magnetism the alternator is ok and the problem is on the regulator side. If not then the sliprings have a bad connection.

[JimsCAL]

I have a Yanmar 3GM30F, and yes the fuel pump is mechanical as is the engine stop/fuel cutoff. So no electrical load there when running.


Sounds like with solar and a gas generator, you do have ways to charge the start battery. But attempting to have the Balmar repaired at least temporarily or getting an inexpensive internal regulated alternator would be good insurance.

[Vartok]

While you may have a mechanical fuel pump, you do not have "mechanical" spark plugs. All engines require electrical power to run. With a working alternator you can run an engine without a battery using the power generated by the alternator/generator. If your alternator is not working, you can run the engine with out it, but you will continuously be draining the battery until it does not have enough power to ignite the spark plugs. Then you are dead in the water.


Could solar keep the batteries charged enough to run? Possibly, but personally I would not try it.

[Sailmonkey]

Originally Posted by Vartok

While you may have a mechanical fuel pump, you do not have "mechanical" spark plugs. All engines require electrical power to run. With a working alternator you can run an engine without a battery using the power generated by the alternator/generator. If your alternator is not working, you can run the engine with out it, but you will continuously be draining the battery until it does not have enough power to ignite the spark plugs. Then you are dead in the water.


Could solar keep the batteries charged enough to run? Possibly, but personally I would not try it.

Those pesky diesel spark plugs require frequent cleaning too.

[Wotname]

Originally Posted by Vartok

While you may have a mechanical fuel pump, you do not have "mechanical" spark plugs. All engines require electrical power to run. With a working alternator you can run an engine without a battery using the power generated by the alternator/generator. If your alternator is not working, you can run the engine with out it, but you will continuously be draining the battery until it does not have enough power to ignite the spark plugs. Then you are dead in the water.


Could solar keep the batteries charged enough to run? Possibly, but personally I would not try it.

Yes, you are correct. The OP does not have "mechanical" spark plugs on his engine. In fact he will be hard pressed to find any sort of spark plug on his engine. It seems these diesel engines have progressed to the point where they no longer fit spark plugs to diesel engines. The wonders of technology hey!

And FWIW, the 3gm30F does not have glow plugs either.

[valhalla360]

Originally Posted by Wotname

Your engine has decompression levers so the easy way to reduce the electrical load on the starter battery is to use them when starting the engine. You will get a heap more starts from a battery by doing this.

1. decompress all 3 cylinders.
2. spin the engine over using the starter motor for say two seconds.
3. compress one cylinder and as soon as it fires, stop using the starter motor.
4. compress the next cylinder
5. compress the last cylinder

You may have to experiment a bit to get the timing right and the best throttle setting but I have found a throttle setting around the 1200 to 1800 rpm is a good starting point. It will depend a bit on how easy it starts normally.

Unless there is a starting issue, it's unlikely this will save any significant amount. In fact if it starts in a second or two, it's likely going to eat up more amp-hr as the process is likely to require the starter to keep turning over the engine for longer.

[JimsCAL]

Originally Posted by Vartok

While you may have a mechanical fuel pump, you do not have "mechanical" spark plugs. All engines require electrical power to run. With a working alternator you can run an engine without a battery using the power generated by the alternator/generator. If your alternator is not working, you can run the engine with out it, but you will continuously be draining the battery until it does not have enough power to ignite the spark plugs. Then you are dead in the water.


Could solar keep the batteries charged enough to run? Possibly, but personally I would not try it.

Thanks Vartok. I needed a good laugh this morning. Hint: Read up on how diesel combustion works.

[Wotname]

Originally Posted by valhalla360

Unless there is a starting issue, it's unlikely this will save any significant amount. In fact if it starts in a second or two, it's likely going to eat up more amp-hr as the process is likely to require the starter to keep turning over the engine for longer.

I beg to differ although I do agree that if the engine starts readily, not many amp hours are saved while the battery remains close to full charge. In the OP's instance, his start battery will discharge over time until it will struggle to turn the engine though compression fast enough to generate enough heat to fire. By starting decompressed, a near flat battery will easily start a 3GM30 (IME).

After the initial inrush current, the current draw of the starter motor rises sharply as each piston approaches TDC on the compression cycle. A discharged battery simply can not supply the necessary current to push the piston though compression. However decompressed, the starter motor requires much less current and what energy is supplied is essentially stored in the flywheel.

The current draw of a starter motor (which is always series wound) is directly proportional to the torque generated and inversely proportional to it's speed. Thus in a low torque and high application, the current is minimal. Decompression allows the starter motor to operate at lower torque and higher speed than a compressed engine.

[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. If you did the magnetism check correctly (ignition on) and don't get any it means your field is not getting current or the alternator can not complete the circuit to ground. You say the readings at the regulator are accurate, can you describe this?

Balmar series 9 are isolated ground so first thing is to check the ground wire. Disconnect, clean, reconnect and check continuity. Ideally the wire should go to the battery negative and be of the same gauge as the positive one. Now check again for magnetism. If no magnetism present connect 12V to the field wire (jumper). If you get magnetism the alternator is ok and the problem is on the regulator side. If not then the sliprings have a bad connection.

Thank you....
You make some very good points here and I think this is what caused my hesitation and passiveness towards the issue initially. I still now have thoughts that after a couple hours of motoring it will come back alive. I will however promote that by checking the contacts on the alternator for corrosion, maybe loosen and clean as good as I can and tighten them up again.

So the test I did for magnetism was detach plug from regulator and connect the red to the blue with a wire. Does that sound right? I’m pretty sure it’s 12V coming from the red wire. Now, Does the black wire need to remain connected to regulator during that test? I’m guessing that might have been the problem if so.... checking now!

(I just checked keeping the black wire attached, I also tested the red wire and jumper for 12V, it’s there, and when connected to the blue, still no magnetism - I’ll give the contacts on the back of the alternator and any other connections a look in the morning.)


The readings I got are here:
—-
Measurements from the ARS-2. With engine at 1,400RPM, 1,000RPM, and only ignition on.

- 1,400RPM
RED - 13.51
BROWN - 13.32
BLUE - 13.30 and dropping

- 1,000RPM
RED - 12.92
BROWN - 12.78
BLUE - 12.89

- Ignition on only
RED - 13.01
BROWN - 12.58
BLUE - 12.89 and jumping around

[lordgeoff]

Originally Posted by small ac999

The battery also powers gauges, fuel pumps. Etc.

I would not run an engine or move a boat without an working alt. It is very important. Fix it.

I have always had two alternators on my Perkins.
Solves all sorts of contingencies.