Hi all,
I have a multirs 3p setup with victron vm-3p75ct grid meter, PV both on AC-out and on the builtin MPPT.
In the VRM dashboard control section, there is the ‘Input current limit’ setting.
(I was testing this given that DESS sometimes throttles mppt solar when charging from the grid: DESS throttling mppt solar while charging from grid - #3 by gvs
Instead of setting a fixed charging limit to prevent this, which would limit charging also on the not so sunny days, the grid input limit setting can be changed relatively easily so it looked like a good alternative)
However, it seems the grid ‘input current limit’ also functions as a grid ‘output current limit’. I assume that what is meant is a current limit on the ‘input’ port.
So I wondered what would happen if I would set this limit to a lower value to avoid the throttle issue, but would forget to turn this off before the battery reached 100%. When testing this, I found that with a grid input limit < PV power, when the system reaches absorption voltage, the system first maximizes grid output current (according to the set limit), but then just keeps on charging above absorption voltage. I would have expected the unit to at least throttle / switch off the builtin MPPT before doing this? And if the AC PV would then still provide too much power, to disconnect from the grid and raise the frequency?
I did not test to too high voltages (~0.75 V above my default absorption voltage of 55.2V), so there might still be an extra safety mechanism that is only activated at higher voltages, before the BMS overcharge protection cuts in. I did not find any setting related to this however?
Still, the input current limit setting is easily reachable, and having such a setting potentially push the system beyond the set absorption voltage does not seem ideal.