I’ve got a Multiplus 12/3000 on our boat that’s dropping the output voltage in bypass mode.
From what I’m seeing it has to be internal; a bad internal transfer switch or cold solder.
AC output will drop down to anywhere from 0 vac to 70 vac.
AC input does not drop
Voltage can stay low for seconds, or for 10-20 minutes
It happens when there is very little load.
It happens in bypass mode (“charger only”).
Have not seen it happen in inverter mode (“on”)
It’s intermittent, can go for weeks without happening
Drop is indicated in VRM.
Drop also evidenced by low voltage alarms in my HVAC thermostats (so it’s really happening).
Not necessarily. The incoming mains supply can be rejected by the MP not only due to voltage, but also due to current or frequency. Essentially if any critical value of the mains is outside its acceptance window, the input relay will disconnect. If the MP is in On position it will then take over the load. If its in Charge position the load will be dropped.
If you also track mains current and frequency on the graph, then maybe one of them will also have a drop/peak at the same time. If not, then you could start to think about an internal issue.
If you have set a gridcode in the MP, the allowed margins usually are much more narrow than without a gridcode, but there would also be a LOM or disconnect log that you could readout. Whithout a gridcode theres sadly no such log.
