What isnāt clear to me ā or possibly anyone outside Victron! ā is what the various Quattro voltage settings and modes (Bulk, Float, Absorption, Sustain) mean or do when an external BMS is controlling chargingā¦
With the Quattro in charge itās clear ā bulk charging is constant-current until it reaches the absorption voltage (56.8V in my case) where is stays for the programmed time (e.g. 2 hours), then it stops charging until the voltage drops down to the Float voltage (54V) where it is then held. The mode changes depending on where the Quattro is in this charge cycle.
When solar/wind it prioritised, it uses solar power instead of shoreline if available (Sustain mode), unless a week passes without hitting 100% SoC (which I assume is defined as the absorption voltage being reached?) when it triggers a ācharge to 100%ā cycle, and then doesnāt return to sustain mode, it stays in Absorption mode.
(the documentation says this period is a week, but in VEConfig it kind of implies that this can be changed with the absorption repeat delay setting ā does anyone know for sure which is the case?)
Is this all correct?
So what happens when itās under external control from a BMS, in my case with 100% SoC defined as 57.3V and Float voltage as 54V? The BMS normally stops charging at 54V by setting the CVL, but once a week raises this to 57.3V for 2 hours to balance the cells and reset the SoC counter ā assuming thereās enough solar. If there isnāt and voltage drops below float, once SoC reaches 95% the CVL is also raised from 54V to 57.3V.
So how does the Quattro decide what mode itās in (and what do they mean with external control?), and when does it switch between them?
Should I set the Quattro Float voltage to the same value as the BMS one like it is now (54V) or lower?
Should I set the Quattro absorption voltage to the same value as the BMS one (57.3V) or lower? (itās currently lower at 56.8V)
If the BMS raises the CVL to 57.3V after 7 days but the Quattro delay is set to 14 days what should happen ā nothing until 14 days (SoC continues to fall due to lack of sun) then a charge to 100% SoC? (which should work)
Once this has happened, is there any automatic way to get the Quattro to go back to sustain mode, and wait another 14 days before the next āCharge to 100%ā is triggered?
This would be preferred behaviour so that whatever solar power is available is used (even if it canāt keep the batteries full) rather than shore power.
Iāve attached a plot showing what has been happening ā in each case I manually stopped the āCharge to 100% SoCā since there was no sign of this happening automatically, next time Iāll leave it alone for longer and see what happens.