I would like to ask Victron and the community some help in diagnosing what could be causing this...
I have a 2x Multi parallel setup. They are matched, DC input current is reasonably balanced, measured with DC Amp clamp. In Winter, I have the system inverting by day and switches to GRID and 22h to take advantage of cheap tariffs and protect the batteries. The AC input limit is set on Venus about 14A, as I have around 3.45 kVA available from grid (15A @ 230V).
Recently I have been noticing that the powerassist sometimes kicks in well below this 14A input limit. And the following was an event, 2 days ago, that really worries me.
Batteries were about 40% discharged, and at 22h the system started charging from grid. the AC loads at that time were no more than around 300W and charge current around 35A. All normal.
Now, picture 1 shows when I started the washing machine (~2kW on AC out) at same time batteries were charging. Seems also normal, and is what I expected:
But some moments after I noticed the charge current dropping to almost zero:
And there was some strange noise in the Multis at the same repetition rate: seemd like charger starting every 3 or 4 seconds. Current droping from 30A to zero and repeating in some seconds interval. But it got weirder, sometimes powerassist also came into play:
And it went into passtrough sometimes. Here's the complete scenario, until I gave up and stopped the washing machine:
You can see the oscillations in VRM:
So, if only charging, no problem. But when high loads and charging is needed at same time, it got a little crazy. I have firmware version 459 in the Multis since more than 9 months. Only now I noticed this. It coincided with latest Venus OS but there may be no relation. However, I did notice some strange facts:
1. The currents and power in the Venus OS menu are somewhat suspicious. I assume the power is the "real" power, and current is also "real" or does it take reactive power into account? Because 14.8 A x 233V is much more that 2436W. PLus, I measured with AC clamp, and the meter only showed about 10A coming into the system (common to 2x Multis).
EDIT: this measurement is from a date earlier (2 weeks before) the event above. Input limit was 15A at that time. I was puzzled about which vales are real power and which (if any) also take into account the power factor.
2. Upon the strange event above, I downloaded the configuration of the Multis and checked with VE config, I noticed that only one of the Multis has 7A on the AC input limit. The other one only had 3A set. I find this odd, as like this the system cannot obbey the 14A limit set on Venus OS...
Any help very much appreciated.
EDIT 2: this is the current 2x Multi Setup configuration:38d2692bc6a4_inst_ttyO5_Interfaces_Mk2_Tunnel.zip