alternator charge warning light always on

[markxengineerin]

The engine is a Yanmar 4JH2E with "C type" control panel- which has the usual alternator low charge output warning lamp. It has been illuminated permanently since before my time with the boat, and I'd like it to be functional again (warn when the alternator is not providing a charge).

The alternator was upgraded by previous owner to a Ham Ferris Powermax 125. It is externally regulated, and now charging the house bank, not the engine start battery as shown in Yanmar wiring diagrams.

My question is, what is the right way to wire the low charge warning lamp for a house bank and this alternator? The generic diagrams I've found all show the alternator warning light getting 12V from an ignition switch (in my case would have to be from house bank) and connecting to a terminal on the alternator, but the label of that terminal varies.

The Ham Ferris Powermax has 4 electrical connections, and only 3 are used right now. The usual + and - to the battery bank, and the Field excitation coming from the external regulator. The unused connection is right next to the Field connection, and it looks like it's connected internally to the diodes. Is this the proper pin to connect the indicator lamp to, the one that is "ground" when the alternator is not charging, and = battery voltage or higher when the alternator is charging?

[smac999]

What reg? The balmar has a lamp output.

I don’t think the alt will have anywhere to connect a dash lamp too now that is external regulated.

It’s very odd that it’s on though. If the wire was disconnected it would be off not on.

[stormalong]

That unconnected terminal is most likely a tachometer output. I am not familiar with Yanmar but seem to have read that they have a separate tach sensor.

[Emmalina]

As mentioned it is probably a "w" connection from the windings to give a tacho output. How can you have a low charge light without having a shunt to measure the current output ??? Or do you mean low voltage ?

[markxengineerin]

The regulator is a Heart Incharge
https://www.cruisingequipment.com/pr...lpha/alpha.pdf
There is no discussion in the manual about a warning light.

I meant low voltage, not current, sorry.

Based on another image I found this morning, it does look like the un-used pin is or a tachometer output "R".

I do not use it because yes there is an external tach sensor on the flywheel.
Unfortunately I don't have the rest of this picture, it is cut off, but I have a feeling there would be no mention of a warning lamp.

I would not be afraid to tap into the regulator circuit board, if I knew where to do it, to connect the "ground" side of the warning lamp. Does this seem like the only option/ is it possible?

[markxengineerin]

I traced the wire coming from the "charge" warning light and it is connected to alternator ground. That would explain why it is always on. What I need is a location in the alternator or voltage regulator which is ground when there is no charging happening, and is = battery voltage when charging is happening. It looks like a pin with this function is normally provided by a voltage regulator. I would like to retrofit one

[hzcruiser]

Originally Posted by markxengineerin

I traced the wire coming from the "charge" warning light and it is connected to alternator ground. That would explain why it is always on. What I need is a location in the alternator or voltage regulator which is ground when there is no charging happening, and is = battery voltage when charging is happening. It looks like a pin with this function is normally provided by a voltage regulator. I would like to retrofit one

Please let us know how you succeeded.

[markxengineerin]

I did not succeed, will come back to this when I have more time but for now I have left the light disconnected.

[hzcruiser]

Have you checked the voltage output on the exciter or field wiring of your alternator? ? It seems like that would do the job.

See also:

https://i.stack.imgur.com/ln6UA.gif

[smac999]

Originally Posted by markxengineerin

I did not succeed, will come back to this when I have more time but for now I have left the light disconnected.

You need a regulator with a dash light output. Like a balmar 614. It will warn for low voltage, high voltage. Or high alt temp. (If alt temp sensor added) If you hook the tach output to the reg. Then it will also warn on the alt stoping.