I have an installation with a large lithium battery, (ZYC brand), which is communicating with the Victron system via a CERBO device, the batteries govern the charge voltage and durations. The MPPT charge controllers correctly indicate BULK mode, (blue LED), at the start of the day and then switch to the orange LED, indicating ABSORB as the battery gets near to 100% charged. The FLOAT LED, green never illuminates.
What governs the LED display on the MPPT, is it the battery BMS, (indicating some glitch in the a ZYC software), or is it in the settings on the MPPT?
The MPPT units, (3 of), all have the ZYC settings loaded, as per the ZYC documentation but for some reason the FLOAT LED never illuminates. Even after the programmed 4 hours of absorb time has expired.
Any suggestions on the LED control and how this can be remedied would be appreciated. The batteries appear to be charging correctly but the LED display is not in sync when float starts.
The lights work differently under external control from the BMS via the Cerbo. Bulk is when the controller can not achieve the required voltage because the battery can accept more current than the charger can produce. Absorption is when the charger does reach the set voltage. The batteries BMS will send a required voltage of say 14.2V and when they are full reduce this to say 13.5V. The controller does not know this is float, this is just a target voltage so it always considers it as the absorption voltage. The settings in the charger are ignored under external control.
Thanks for the information, the first part, about why the bulk light comes on makes sense, the second part about the charger not reaching the set voltage doesn’t sound right. I would have thought it would have been in absorb mode when the voltage WAS achieved and it was under current limit to maintain the voltage set point.
Is the information you provided from a manual or experience? I’d love to find a reference document from Victron that covers this issue.
I do not know if it is in a manual, but it is well known among the more experienced users. Under external control the charger has no concept of absorption or float voltage, it just has a variable target voltage.
Regarding not understanding the second bit, I can not see an error, I said absorption was when the voltage was reached.
Thanks for that, somehow I read a ‘not’ in there about the absorb time.
So just to be clear, for others who may read this.
If the battery is controlling the charge then the MPPT indicator LEDs are illuminated according to the following:-
Bulk LED illuminated when the charger is supplying power but has not achieved the Absorb voltage level.
Absorb LED illuminated when the charger has achieved the absorb voltage.
Float LED will not be illuminated.
And you are not aware of this information being within a manual.
I believe it would be good if the Victron software team could amend the LED illumination algorithm to match the battery control status, although this would require the battery to send a clear status signal to the GX device advising if the battery is in bulk, absorb or float. I wonder if the battery(s) already do this.