I recently installed a REC BMS with 560 ah lithium batter along, with a Multiplus 12/2000/80 (we have had the Mplus for 5 years). The two communicate using the Can.Bus connections on our Cerbo GX, so the Multiplus is listed as under "ext control" (i.e. slave to our REC BMV) on the Cerbo's interface.
I'm not too keen on leaving the charger on the Multiplus turned on as I do not like the short sawtooth pattern near the top of charge on lithium batteries. I prefer turning off the charger, and allow our solar panels keep up as much as possible during the week. When we are close to going out I can pull out my phone, put on the charger and raise my SOC to about 80-90% fairly quickly. One thing I have noticed is that when I turn off the charger by clicking on "Inverter Only," in the Cerbo Interface, the inverter only portion of the Multiplus seems to stops using shore power. AC IN Line 1 shows 110 v, 60 hz but no current or power are being used; AC Out Line 1 shows that whatever current and power used are provided by the battery. I can't remember if the Multiplus did this on my previous configuration, as I mostly used the charge setting to provide float voltage (so I didn't really use "Inverter Only"). My question: is this not-using-shore-power a normal behaviour when the Multiplus is physically connected to the shore, but in "Inverter Only" mode? Or is this a function of the REC BMV? Or is this a problem with my inverter? Perhaps I don't have things set up properly? Any coaching would be greatly appreciated if this is the case.