no charge signal beeps every 10 - 60 sec

[P435]

Volvo Penta MD2040
Alternator: Valeo, exact type cannot be indentified since it type plate is painted; image attached.


The beeping signal appears roughly every 10 - 60 sec in irregular periods. It is accompanied with the "no charge" indicator lamp signal at the engine control panel at the helm station.


At the beginning the beep appeared only once the engine was running for 1 - 3 h. Now the beeping start shortly after the engine starts.


The alternator appears to charges normal. Voltage measured is normal 13.9 V depending a bit on the RPMs. Never measured at high RPMs

Questions:

1 - What could be the cause of the beeping?
2 - What is a possible remedy?
3 - What could be the exact type number of the Valeo alternator?

Thanks in advance for helping comments.

[rickp]

Failure of the alarm unit in the control panel?

[colemj]

That is a 60A Valeo internally regulated alternator that is OEM on the engine. It sounds like the panel believes the alternator is no longer charging when it beeps. You need to measure the current from the alternator, not the voltage, when the panel is beeping, to determine if the alternator is still charging.

The charge indicator warning circuit works by having voltage/current run to ground from the panel when the alternator has no output. When the alternator has output, it supplies voltage/current to the warning circuit and cancels the path to ground and the light/alarm goes off.

It's possible the alternator is working, but the signal path back to the panel is compromised. Check the several ground wire connections on the panel, the blue/red and brown/white wires and connections on the D+ terminals on the panel and alternator, and the yellow voltage sense wire on the alternator and the battery (or wherever the connection point is in the charging circuit).

Mark