Hitachi alternator no output

[SailBelladonna]

It is connected from Blue/Black on the alternator T to B+.

[Wotname]

Originally Posted by SailBelladonna

This was the red wire shown in the wiring diagram.

Originally Posted by SailBelladonna

It is connected from Blue/Black on the alternator T to B+.

Great, got it.

Also you previously mentioned "fuel pressure sensor"; I am assuming you meant "low oil pressure sensor"

Working through your before and after drawings ATM.

[Wotname]

Originally Posted by SailBelladonna

..............
Here is the initial design before installing lifepo4 and changing to seperate starter batteries.

As is electrical design – Sailing Belladonna

No buzzer issues before I started playing and all charge lights working correctly. The "distributor" refers to the split charge diode.

And here is the design after the electrical changes:

Future state electrical design – Sailing Belladonna

...

OK, more questions (sorry...)

It would be helpful to know the following aspects which aren't detailed on the drawing but are important.

Yanmar has the alternator B+ connected to the starter motor but this (apparently) has been disconnected according to your drawings. There is nothing wrong with that but it begs the question, where is the 30amp fuse that powers the engine panel connected to positive? Presumably still at the starter motor? See red circle...

Is it the same for both engine panels?

Are both engine panel 30 amp fuses still connected at the starter motor after your modifications?

Can you confirm the following - one alternator has the red/black wire (R terminal) cut and the alternator does not (i.e this wire is still connected back to the key switch).

Which engine has the cut wire?

And both alternators are charging OK ATM?

[Wotname]

SailBelladonna, I have reviewed you 'after' diagram and can find nothing unusual about it. It is simple and straightforward and FWIW, I like it

Assuming your existing alternators have not been modified internally and the Hitachi internal regulators are serviceable, they should be connected as per the Yanmar diagram. I.E. the charge lamp wire (blue/black) direct to the L terminal and the W terminal (red/black wire) direct to the key switch. Ensure the engine panel / key switch is getting power (via the 30 amp fuse) from the same battery as alternator.

Each engine and alternator is independently powered by it's own battery. Each should work in the same manner. If one isn't working, then we have to chase down the fault. I'm happy to keep assisting if you desire.

There is simply no call for the 'red link' joining L and B+ terminals and likewise there is no need for the cut off red/black wire.

I'm curious though, as to why the port engine has the negative side switched through a master switch while the starboard engine doesn't? Just a legacy thing????

[SailBelladonna]

Originally Posted by Wotname

OK, more questions (sorry...)
Yanmar has the alternator B+ connected to the starter motor but this (apparently) has been disconnected according to your drawings. There is nothing wrong with that but it begs the question, where is the 30amp fuse that powers the engine panel connected to positive? Presumably still at the starter motor? See red circle...

I have found the 30Amp fuses on both engines hidden under the air intake. They are between the starter motor and the key switch. They are the same on both engines. It is so difficult to find colours since every is sprayed grey to make the engine look nice from the factory!!

Originally Posted by Wotname

Can you confirm the following - one alternator has the red/black wire (R terminal) cut and the alternator does not (i.e this wire is still connected back to the key switch).

Both engines have the red/black wire cut at the alternators. They both appear to still be connected at the key switch. But there are three wires connected to the key switch terminal AC - brown, red/black and white. The brown is connected to the tach.

Originally Posted by Wotname

And both alternators are charging OK ATM?

Yes both alternators are charging well with the original wiring as per my drawing, BUT buzzer perm on with ignition off.

[SailBelladonna]

I have reconnected the cut red/black wire and disconnected the 'red link' joining L and B+

All light buzzers etc are working BUT the alternator has no output.

[Wotname]

Originally Posted by SailBelladonna

I have found the 30Amp fuses on both engines hidden under the air intake. They are between the starter motor and the key switch. They are the same on both engines. It is so difficult to find colours since every is sprayed grey to make the engine look nice from the factory!!

Yep, bludi annoying they way they do that!


Both engines have the red/black wire cut at the alternators. They both appear to still be connected at the key switch. But there are three wires connected to the key switch terminal AC - brown, red/black and white. The brown is connected to the tach.



Yes both alternators are charging well with the original wiring as per my drawing, BUT buzzer perm on with ignition off.

Originally Posted by SailBelladonna

I have reconnected the cut red/black wire and disconnected the 'red link' joining L and B+

All light buzzers etc are working BUT the alternator has no output.

I think you have two ways of solving these problems.

1. Determine why the alternators are not working when connected exactly like the Yanmar expects them to be. This may not be easy if you don't have access to a good alternator repair facility as I am fairly confident the fault is inside both alternators as unusual that might be. However we can do further diagnostic testing to further determine if my suspicion is correct or not. My hypothesis may be wrong and further testing could prove/disprove it.

2. Do the quick and dirty method. Keep the modified harness in place (ie with cut wire et al) and use a diode to prevent the +ve feedback through the Charge Lamp to keep the buzzer quiet when the engine is OFF. This diode will not (or should not) affect normal buzzer operation or Normal Charge lamp operation. I would use diode rated for about 5 amps. It goes in the Charge Lamp circuit as shown in red on the attached drawing.

While method 1 is the pure approach to resolving electrical issues, there is some merit in method 2 if you are far from home.

[Wotname]

Opps.. attachment coming shortly!

OK, attachment should now be visible in previous post!

[SailBelladonna]

Thanks so much. I am going into town to see if I can source a 5amp diode being in Tahiti nothing is easy to source.

You have been so helpful and so generous with your time - very very appreciated.

[Wotname]

Originally Posted by SailBelladonna

Thanks so much. I am going into town to see if I can source a 5amp diode being in Tahiti nothing is easy to source.

You have been so helpful and so generous with your time - very very appreciated.

5 amp is belts and braces. If you can't find one, get the best you can. I would try a small signal diode if I had too - say 1 amp. Something like a 1N4007 - at least to try.

[SailBelladonna]

Fantastic - thanks

[Wotname]

^^ I checked the specs and I was being way over cautious will the 5 amp bit. I don't know what wattage Yanmar uses for it's charge lamp but 3W is common. So let's say worst case is 6W. That equates to ~500 mA when full bright. Remembering the charge lamp is OFF for most of the time, a 1A continuous diode is ample e.g. 1N4001, 1N4004, 1N4007 etc.

Let us know if you can find a diode and if it works out OK - otherwise we are back to the drawing board.

[SailBelladonna]

Thanks again - going to town on Monday to see what I can find.

[sailorladd]

My immediate thought was that a diode had blown...it happened to me a couple of times.

[SailBelladonna]

Originally Posted by sailorladd

My immediate thought was that a diode had blown...it happened to me a couple of times.

I did take the alternator out and test the diodes. The fact that the issue is on both engines leads me to the fact the my rewire went wrong