I have just about installed Multiplus 48/1200/13 and hooked it up to Li-ion 14s1p batteries.
It has been working perfectly in UPS mode and pass through. To test the capacity, I turned off the mains and the UPS kicked in, I let the system run - till the cut off voltage was reached.
When I turned on the grid/mains - the RCD (on the mains consumer unit) tripped. It did this a few times. I disconnected the load and the same happened (rocker switch in ON position). Then I switched it to charger and it did not trip.
I tried various combinations and unfortunately - the RCD tripping is very random and not reproducible.
AC in comes from the grid
AC out goes to feed a total of 250W (a few pumps)
Any input or help would be appreciated.