question

The first thing that comes to my mind is that the shore power is not sufficient enough to supply the full power that the charger is now demanding due to the batteries being really low.

Can you limit the shore power in the Multiplus to a lower level?

I have a Diesel Duck as well with the same inverter/charger. In my case, the charger won't engage at all. I was also told that the low voltage of the batteries was keeping the charger from turning on. So I'm running the engine to bring back the battery bank - 4 8Ds. If that doesn't work, I'm to disconnect the battery bank and test each battery's voltage to see if an individual battery has gone bad. I tried an inverter reset - which consisted of turning everything off and then back on in a specified order. In my case that's shore power at the shore pedestal, shore power at the distribution panel, the inverter switch on the remote panel and then the inverter switch at the box in the engine room. After 10 minutes I was instructed to turn on the engine room box, the shore power pedestal, the shore power switch at the distribution panel and finally the inverter switch on the remote panel. That wasn't successful for me. The boat is new to me, but this wasn't the kind of Christmas present I was hoping for!