Last fall I installed a Multiplus II, BMV-712, and Smart dongle with 4 lion energy 105 AH lithium batteries in a fifth wheel. I do not have solar. This is the first time I have installed this type of equipment, so I am learning. From the time I installed the unit there has been about a .6 volt or 5% difference in the voltage readings between the MP2 and the BMV. The BMV was always lower. It did not matter what I set the absorption rate or float to. If the MP2 was set at 14.4, the BMV would read 13.78 or very close to it. If the MP2 read 13.88, the BMV would be 13.25. I used a pretty good multi meter to check the battery bank, one battery by itself and the cables going into the MP2 and its readings were always the same as the BMV.
Additionally when I would be hooked to 30 or 50 amp shore power there would be a negative current reading on the BMV, -1 to -2.34 amps. Please correct me if I’m wrong, but while hooked to shore power shouldn’t the pass through relay close so the power comes from the shore power and not the batteries?
I unhooked the MP2 and isolated the battery bank. I unhooked the 12volt wire from the bank at the lynx. There was nothing to draw any energy from the batteries. I checked the BMV and there was zero draw which leads me to believe the batteries are fine and the issue is with the MP2.
I sent this unit back the distributor to have it tested. They said it tested within their specs but are making more inquires to Victron. Their tech support does not know why my system is preforming this way.
Does anyone have an idea why this unit is not charging to what it is set to and what the remedy is? Thanks for your help.
