I have been trying a daily absorb these last 2 days but with 10 minute absorption time as that would be better when I am cruising with shorter engine run periods. Yesterday and today I had over 3 hour absorption times, c!early the rules are not working, or are too rigidly coded or the user settings are having no effect and the code only uses default values. I will pass my experience on.
Tried to upload some images but they will not upload.
Surely Victron could do something similar to what my REC-BMS does? That holds a float CVL of 54V (charging from solar here, about 99% SoC) until the SoC drops below 95%, then the CVL is upped to 57.3V. When it reaches this it’s held there until cell imbalance falls to 10mV, then SoC is reset to 100% and charging is stopped, CVL is reset to 54V, and the battery voltage drops back until it gets back to the 54V float voltage.
The attached shows a “normal” cell balancing/SoC reset cycle where it held at the balancing voltage for about an hour (cell imbalance dropped from 40mV to 10mV), this typically happens every couple of weeks. After a long time out cruising without a full charge (several weeks, maybe 8C throughput in and out), the maximum imbalance I saw was 150mV and it took about 14 hours to get back to 10mV and stop balancing, see second plot.
The relatively long times are because the balancing current is a bit less than 1A and the cells are 700Ah, so 14h is about 2% capacity imbalance (0.25% per 100% DoD). AFAIK the Victron NG batteries have considerably bigger balancing current compared to capacity, so should do all this more quickly.
Yes, that is what they are meant to do, but the end of absorption / balancing phase is not stopping correctly when cells are balanced or if the time limit is reached. The settings in the Lynx BMS are not user accessible.
@hennephuis finally uploaded the screenshots from an absorb set at 10 mins with balanced cells after current reduces.
Thanks for the graph. I can tell from it that the battery cells were balanced way before 12 o’clock but the voltage remains at 3.5V until 14 o’clock’ish.
Just to be sure: Victron does not detect balanced battery cells and does not use that to terminate absorption. No surprise here. @iand’s suggestion is key here, although I would probably do it slightly differently.
It also seems like more than 10 minutes absorbing (duh). Not good. That is because it misses its timer as a result of the ripple (my hypothesis).
Do I understand correctly that you (@pwfarnell) are now also confronted with the same problem as @zedamoca and me, @hennephuis?
Here is a graph from today. It initiated the first charge cycle after I set the absorption voltage to 55V and the monitoring voltage to 54.9.
It raises the voltage to 55V around 13h’ish and very soon it sync’ed to 100% charge. This is what I hoped and expected.
Then it keeps the voltage at 55V forever, at least till 18h, also as expected, but not what it should do. I expect it to lower the voltage when the cells are balanced. They were balanced all the time as one can tell from the min/max cell voltages.
I think that both bugs are (again) clearly demonstrated. At the same time, there is a third bug, namely that I lowered the SoC level at which it must start a full charge cycle to 50%, but it still does so at 70%. Most likely because this setting is duplicated and not synchronized. Maybe that is already a topic; I will look for it.
Yes, I have had longer absorption times than set when on alternator charging. I have increased my SOC threshold to get an earlier absorption and that works and reset to 70% OK but I have not tried a lower SOC threshold.
Today was a funny day.
I took half of my batteries of service yesterday evening because I was relocating them, and didn’t finish yesterday.
This is the new place 
So, because there was half of the capacity, this night (and morning) they went to 59,5% SoC when my setting to start a new absorpion cycle is 60%
