Alternator charging query

[gus]

I have a 24v 30 amp CAV alternator being regulated by an external regulator. When the batteries are fully charged the red warning light flashes intermittently. Apply an electrical load and the flashing stops. Switch off the load and the flashing returns. Have had the alternator and the regulator checked by Lucas but no faults found. Seems to all work okay but this flashing is disconcerting. Has anyone any answers?

 

[byron]

Hey Gus, On my previous boat if I had charged up my domestics whilst in Port for a goodly while using my hefty charger, on leaving port the red light would stay on for that particular engine. Applying a load would cause it to go out. I assumed rightly or wrongly that this was because the batteries were charged up beyond the capacity of the alternator's ability. This is only an anecdote I'm sure more knowledgeable folks will give you a definative answer.

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[HaraldS]

it is not a malfunction, but it says something about your system.
When your batteries are full are full the regulator withr educe the field voltage down to a point where the alternator is essentially off and that will trigger the light. Apply any load and the battrie voltage drops enough to kick in the alternator to cover the load and the things goes off.
Maybe your batterie capacity is a bit low, from a certain size up, just the float charge should keep the alternator a little bit busy. Also it seems to indicate that he regulator is probably one intended for cars (trucks). You should check the battrie voltage with a digital multimeter when the light start flickering. It should be around 28.2 to 28.5, if it is any lower consider getting a three stage regulator like the sterling.

 

[charles_reed]

It's quite normal, especially with an Adverc.

Essentially the regulator is cutting out the charge because the maximum voltage has been reached and the batteries are fully charged - the light comes on. As the charge in the battery drops the alternator kicks in and charges for a few seconds - the light goes out.

My indicator works the other way around - the light is on when system voltage is below 12.5volts and it starts to cycle regularly when the batteries are all fully charged.
In between 12.5 and 14.2 volts there is no light on.

 

[gus]

Thanks for the advice. I didn't think I had any real problem but it is good to have reasurance.