Alternator beeping even if charging

[elias]

Hi to all , our alternator even if is charging normally and within the appropriate voltage , on low revs started to beep from the starter panel and sometimes even at higher revs. Anyone with similar issue? How can I disengage the beeper?
Attaching schemes

[elias]

The voltage in d+ and ground is around 9v it’s that ok? I believe not

[Viviane2000]

After burning our alternator I installed a local sourced Italian alt. This alt gave a weird signal to the tachometer and made the tachometer vibrate. The charging voltage was not stable when the starter battery was full, making the tacho vibrate. Since this was a temporary alt (50A) and I've got a new alt (100A) installed I didn't bother too much.

But with the 50A alt and the vibrating tacho I got the engine waring light + beep as well. There is a Voltage level and when the alt goes below that Voltage the warning is sound. With the engine in idle I got the warning every now and then, with higher revs I did not. The new alt gives a stable voltage when charging the starter battery so this fixed the warning for me

[elias]

Hi ,I cleaned the rotor of the alternator ant the alarm stopped for some days . Started again so I got a refurbished one … I ll take the old one for service and understand what was the problem.

[Molo]

We have the same issue.
Changed the alternator to a new one https://www.svb.de/de/lichtmaschine-12v-115a-volvo-penta-d1-d2-d4-d6.html
This had no effect.
Beeping intensifies if there is no load on the alternator.
If the DC-DC charger is working to charge the lithium batteries from the alternator the beeping pauses.

Our temporary workaround is to remove the speaker - which is obvious a bad one for the other alarms of the motor.