I am not sure it is so much of a low "voltage" alarm as it is a low "amperage" alarm. I know the gauge reads volts. But 8 amps right after a start is quite low. I have amp readouts on both of my engines and they get right up there after a start....60-70...and then settle around 20-25 depending on what "appliances" you have running. One alternator seems to by the master and it kicks the other one off when not needed so that is a total of 20-25 amps. So maybe 8 amps per engine is not too far off but after the start it definitely takes a dip.
Prairie 29...Perkins 4236...Sold
Mainship Pilot 30...Yanmar 4LHA-STP...Sold
Carver 356...T-Cummins 330B...Sold
Meridian 411...T-Cummins 450C