Hi all… trying to understand why I get “High charge current” and “High discharge current” alarms.
This system is made up of:
A solar collector of about 10kWp,
Two Victron Multiplus II 48/5000/70-48 inverters (master+slave)
Two Victron 450/100 MPPT
A Cerbo GX
Dyness battery bank with 21.6kWh total capacity, 6 modules
Every day, when batteries reach 100% SOC, I receive these alarms.
I have checked that Absorption and Float Voltages are according to Dyness manuals:
Absorption V = 53.00V
Float V = 52.50V
(these are the parameters I record with the PC app “Ve.bus quick configure” into the multipluses)
In the ESS config I also put “Sustain V” = 49V.
Trying to get rid of the alarms, I lowered these parameters progressively to:
Absorption V = 52.00V
Float V = 51.00V
However I see no change and still measure voltages over these values in the batteries, and because of that batteries are complaining. For example today I measured 53.81V over the batteries.
As I said I program these values with the “Ve.bus quick configure” app. However I also lowered these values in the MPPT config menu (thru bluetooth connection) but I think the local MPPT config does not apply because I see “External control” in the LCD displays of the MPPTs. Right?
Why the voltage over the batteries exceeds my config parameters? This will damage my batteries if not solved…
Thanks for any help!
My battery bank is made up of 6 modules. They are connected 3+3, and following all Dyness suggestions. In each 3 module branch, the (+) cable is connected to the opposite module that has the other (-) cable: as usual in battery banks. If that’s not clear, I can draw a little schema for you.
I don’t understand well your phrase: “You don’t need to reprogram as an fyi when lowering voltages of you have a gx use the voltage cap in dvcc.”
But trying to solve the enigma in your sentence, I saw that in DVCC there is this option: “limit managed battery charge voltage” and I activated and adjusted it to 53.50V that is the maximum value that my batteries support. Is this what you are speaking about? I will see how it behaviours with this new value.
In DVCC menu I see that there is also the option to choose “controlling BMS”, I have these options: “Automatic selection”, “No BMS control” and “Dyness-L battery”. It is set to automatic selection. Is this OK?
Yes both alarms happen one after the other, charge/discharge. But the excess voltage observed over the batteries is consistent: it lasts several minutes.
“Re programming would not have altered anything ad the batteries control the system.” > What do you mean with this: that the voltages I program in the system (Absorption V, Float V) do not apply?
The BMS when it is connected to the GX will override this.
If you look in the battery information either on the GX or the vrm you will see what voltage and charge current the battery is requesting.
OK, then I will try to see what voltage the Dyness battery is requesting -in the remote console: “DYNESS-L Battery/Parameters/Charge Voltage Limit (CVL)”- when these alarms are shown. To catch this will take me some time. This value usually shows 53.5V.
It is usually displayed on the GX does not require a special set of knowlege to view.
If it is continuing to change thise changes are logged to the VRM and can be seen kn the bms widget for the battery on the vrm.
You can load that widget and battery alarms widget and quickly compare what is happening when.
Well, I think I caught the exact moment when the warning is fired. For some reason that I don’t understand, when the battery reaches or is around 100% SOC it seems that the MPPTs are delivering more current than it is requested by the own BMS of the battery. So the battery is complaining because it is receiving more current than it is requesting. I attach pictures of two moments like that.
First set of pictures is at 11:55: battery is requesting 15A but is receiving 127A.
Second set of pictures is at 11:57: battery is requesting 0A but is receiving 64A.
This situation is persistent and may last around 15 or 20 minutes. This will obviously damage my batteries in long term.
Sorry for my long silence. These last weeks I have been adjusting this parameter to different values, to find the one that makes the warnings to disappear. It seems to be around 52.0V.
Leaving apart the concrete value, the fact is that it seems a way to avoid my problem. So thanks LX for pointing me in the right direction.
But I have an important question: must this value be adjusted ALWAYS in all installations? Or I had to do that because of bad behaviour of my system? In theory, these values should be dinamically adjusted according to dialog with BMS, right? Is this something that happens with concrete labels/manufacturers of batteries? Does it happen often? Will I lose any performance because of having to adjust this parameter manually?
You should open a ticket with Dyness. It looks like a firmware issue with their BMS. Trying to fix it from the inverter/gx is not always an effective bandaid.
I assume your battery is a 15 series cell battery, which would mean at 52.5 V / 15 cells = 3.5 Volt per cell, which is already higher than some run their LiFePO4 batteries at.
As for the “must this value be adjusted ALWAYS in all installations”, it probably should, but I’d think this may also be a function of the BMS, some will happily allows cells to come up to 3.65 V, which of course does very little in terms of SoC, since even at 3.45 V per cell or so, you’d have pretty much a full battery pack and you would not be stressing/shortening the life of your cells.
As for “Or I had to do that because of bad behaviour of my system?” Maybe not the greatest BMS (just my opinion) and maybe, you’d have to look though, a badly balanced battery pack.
I run my DIY battery banks (16 series cells) at 55.2 V, aka 3.45 V per cell and they pretty much run without issues and should have a fairly long life at that value, they are also mostly well behaved from a balancing perspective, worst case, recently I saw was around 20 mV delta in a pack.
The BMS will set the desired limits, it would override any incorrect configuration in the charger settings. If the BMS is unhappy with it’s own parameters then it should be raised with the manufacturer, there likely already is a software update for the BMS.
