The thing is the BMS asks for 56.8V for 2 hours for absorption after which it goes to 54.8V as float. You can not adjust these, they are hard coded.
If you have a setting which is holding the voltage to 56.0V then it can not get to the required 56.8V so it will never go to float.
All your changes appear to have really messed up the way the system works rather than leaving it as default or the BMS has suffered some form of failure.
I do not think you will find anyone who has tuned their Victron NG system as it is so new.
I am out of ideas, I remain convinced somewhere you have a setting limiting the charging voltage to 56.0V which is causing all the issues.
I really appreciate your patience in sticking around. Me too, am out of ideas and I’m also convinced something is still being hold the 56V, and because of that 56,8V can’t be reached, not allowing sync.
You mean 54,0V as float, right?
I just made a full system shutdown; Had to wait for everyone to be in bed.
Powered off the MPPT in the switch
Powered off both inverters in the switch
Pulled the power cable from the Cerbo off
Connected over bluetooth to the BMS in Victron Connect and pressed “Turn Off”, the BMS opened, I heard the click from the relay, LED turned red
Waited 1 minute and 10 seconds
Pressed the “Turn on” in the BMS, heard the click again, light turned green again
Plugged Cerbo back in
About 25 to 30 sec later turned the Inverters on at the swich, leds came up green
Turned MPPT back on.
OK, there is some confusion between the manuals and what is configured in the BMS. I believe that the NG manuals were edited from the older Smart battery manuals and not all data has been captured.
The manuals state 13.5V float for a 12V battery and 54.0V for a 48V battery but the BMS is actually running 13.7V on thr 12V batteries, so for a 48V unit this would correspond to 54.8V. The default lithium setting in things like MPPTs remains at 13.5V/54.0V. I am not sure exactly what your will float at, either 54.0V or 54.8V.
For absorption, the manuals variously state 14.0V and 14.2V for a 12V battery, I have gone back and checked my history and mine absorb at 14.0V. For the 48V battery the manual states it absorbed at 56.0V, so your value of 56.0V is the correct value, finally worked through the confusion.
The manuals need correcting and that is on Victron’s to do list
So now, your BMS appears to be working OK apart from the long float. The charged voltage in the BMS should be set to 56.0V or slightly lower. The one thing that can generate a long absorb is if the cells are not balanced, on my first charge they ran for about 5-6 hours in absorb..
Yes I did.
Well, actually I got the confirmation that this value changes by itself. I’m sure I went to bed with the value at 56,8V and when I went to look today after this reply of yours, it was already at 56V.
Meanwhile, I had a look at both Multiplus. These are the screenshots, I haven’t found anything wrong (in my eyes, maybe I’m wrong); both had the same settings.
I was thinking the MP2 could be the “culprit” if it had 56V set, but in this case the charger was off, as I thought it was. Even if it takes the values that are there written and disabled, it’s not 56V anywhere.
So now I suspect the 56V are being given by the batteries itself? The data wires could bring that info, and the BMS is hardcoded to not let go over 56V because they are NG.
I know I updated firmware of the batteries and BMS just before rewiring from 3 phase to parallel… Did I found a bug?
I guess you mean that the battery manual is wrong.
A deeper read today shows the BMS manual points overall to 56.0V, while the Battery manual points to 56.8V
Around 9:29 the battery reached 55.5V
Somewhere between 9:29:32 and 9:29:47 the battery reached 56V and the current started dropping from around 90A to the bottom making the Tail current curve.
Around 9:45 synchronization happens.
Now what I’m finding strange is the current.
3% of 400Ah is 12A,
Current dropped under 12A (and kept under) around 9:33:17
6 minutes later is not 9:45
Maybe its because of the 2S2P configuration, I have 2 parallel banks of 200Ah, in that case it would be 6A. When the last battery drops his current under 6A it starts counting. 9:35:17 it felt under 6A, so also not 6 minutes until 9:45
Lets look backward, 6 minutes before 9:45 was 9:39.
At 9:39:02 current dropped under 3A
Now, the system know that 3A is 3% of each battery or there is a bug that instead of 3% looks for the 3A. I’ll investigate this further in the future.
