I am having an issue I can't quite figure out. I have (2) Multiplus II 48v/3kva in a split-phase 120v/240v arrangement. I have a temporary battery bank installed consisting of (4) 12v 100ah AGM batteries wired in series for 48v. I have set the system to "Charge Only" with a 50A grid current limit so I am effectively bypassing the inverters. When drawing more than 3k watts per leg from the grid, the battery bank voltage spikes over 60v.
Why is this happening?