Hello together,
I use Multiplus II GX for a few days. Installation was easy and documentation good to understand as well.
I use ESS Mode 3 for external control only via Modbus with 3 registers for basic use. Enable charger, Enable Inverter and ESS Power set.
It worked for days without any problems…but today, when I enable the charger, it goes up to the current limit, not matter what ESS Power set. I have no idea what went wrong. My debug log (openHAB) states, that ESS Power is only set to 100W. But charger goes to 30A limit with much more power.
Any ideas?
Thanks in advance.
Sebastian
Maybe you should start with a description, what you want to achieve?
ESS Mode 3 is almost never required for 95% of Use-Cases. Sometimes people tend to choose the “All-Manual-Path” while one of the other modes would perfectly fine serve their needs?
Also you should mention which dbus-paths / registers you are setting precicesly. “ESS Power” doesn’t exactly describe which value you are setting to what 
Sorry, my assumption was, that Mode 3 is clear to the experts.
1.3 - Mode 3
Customer self implements their control loop and grid measurements, and uses the MultiPlus and/or Quattros as simple, remote controllable, bidirectional inverter/chargers that can be set to either charge or discharge an x amount of Watts. Note that the point of control is the AC-input, not the inverter/charger itself.
a) Grid power setpoint - Modbus-TCP registers 37, 40 and 41
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Positive: Take power from the grid.
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Negative: Send power to the grid.
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Register 37 controls the setpoint on single-phase systems, or for L1 on Multiphase systems.
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Registers 40 and 41 controls the setpoints for L2 and L3 respectively.
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These registers have a range of -32768W to 32767W (scale factor=1).
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These registers must be written once every 60 seconds, or the Multi will go into Passthru.
b) Disable Charge - Modbus-TCP register 38
c) Disable Feed-in - Modbus-TCP register 39
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0: The inverter is enabled to feed power into the grid.
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1: Inverter will not feed power into the grid.
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When both Charge and Feed-in is disabled, the Multi will go into Passthru.
So far, these information got out of the official victron docs. And as I wrote, it worked for many days and my actual problem is, that the Grid power setpoint (ESS power in my first post) doesn´t change the real power consumption anymore. Multiplus goes to the upper current limit, in my case 30 amperes.
Sebastian
It is “clear”, how it works - the question is what kind of behaviour you want to achieve?
Most likely it is not required to “implement a customer control loop”, as the system out-of-the-box would automatically manage everything in exactly the way it would be ideal.
For example, beeing in Mode 2 will automatically charge solar, if there is solar, discharge, if theres consumption over solar - and perfectly fine react to the desired grid-point setting (charge battery, if grid point > consumption) without having to touch any other register.
Vice versa, a setpoint < solar *-1 would discharge the battery to grid.
So, Mode 3 is overkill for majority of applications, and people try to implement what dozens of victron engineers already did.
It is not clear to my, why we do have an discussion about which mode I run on my setup. This was not the question and didn´t point me into direction finding the problem.
Anyway, I found my problem. The Modbus client had an internal failure. The register of setvalue on Multiplus was correctly triggered to keep Multiplus alive, but the given value of power was ignored.
After restarting the Modbus instance, it worked fine as expected.
Sebstian