Personally I do not see any concern.
Not Victron chargers raise the voltage, but the battery itself according to the current SOC level. Victron charges according to information that BVD batteries directly provide. Typically first the CCL gets reduced and finally when SOC reaches full charge level, float voltage is set to 55V after BYD battery expect a CCL of 0 amps. Since Victron devces determine a seemingly higher voltage the float voltage on battery is 0,2 to 0,3 volts lower than BYD would expect. So batteries request (mainly current), what they expect in particlar situations. Voltage is only the consequence of current battery condition (SOC).
Since battery does not charge or discharge at that minimal lower voltage, from my point of view no show-stopper.
An additional quesiton would be, who determines voltages better, BYD or Victron The voltage deviations do not deviate between single devices. I observed that pattern widely in my known installations.
The situation in fact seems the reverse of what you suggest? That is - the Victron is reading low - so when BYD requests eg 54.4V then the Victron will charge up to what it measures as 54.4V but of course by then it will measure as 54.7V to the BYD which is 0.3V higher than it requested. My concern is would this be enough difference to trigger some kind of undesired change in the BYD algorithm? The charge curve seems odd to me, however I am new to such lithium batteries so wondered if it is normal.
According to my perception the lowest charging voltage (CVL) that BYD populates and requests is 57,2V. BYD expects the main power control not my CVL but by CCL (charge current limit). The float voltage of 55,0V after charging completion is not set or predefinedby BYD, but by VenusOS (see code in dvcc-py). BYD still defines 57,2V voltage, but 0A current in that situation.
It seems that BYD B-Box L behaves completely different than Premium LVL series.
With a CVL of 54.4V in your case I would be totally relaxed, even if effective battery voltage is 0,3V higher. Assuming a standard LiFePo chemistry that voltage is more than conservative.
When the battery requests a CCL of 0A the system will usually stop charging at the programmed voltages. It is unusual for the BYDs to even reach the 58v it requests.
As has been mentioned some battery manufacturers use the higher voltage request to speed up charge.
Remember that in the battery the ‘voltage’ reading will be an aggregate more than an actual reading.
The inverter reads its terminal voltage.
The other thing to check would be DC ripple.
Thanks Thomas, grateful that you’ve taken the time to look at this and the interesting comparison with your Premium LVLs.
I have a lot more to learn about how it all works, but I’m happy with the takeaway that there should be no danger to the system!
The voltage deviations do not deviate between single devices. I observed that pattern widely in my known installations.