Hi All, I'm hoping there are some REC guru's who can help. My configuration is a REC Q BMS connected via CANBus to a Cerbo GX which is connected to a Victron MultiPlus 24/3000/70-120 via VE.bus. Everything is configed per REC specifications, as best I can tell. What I'm observing is when the inverter is connected to the Cerbo, the REC appears to be controlling the charge rate, voltage and profile; essentially overriding the user-defined fields I set, which is fine... I believe this is what I want.
The issue is once the REC switches the MultiPlus from bulk to absorb, it stops increasing the voltage when it reaches 28.3v. The current in to the battery drops to almost nothing and the Multi looks to be floating voltage at 28.3v while indicating it's still in absorb mode. If I remove the VE.bus cable from the Cerbo GX, it will stop charging after a few minutes.
I've tried a number of things but by testing has me currently at these values:
MultiPlus absorb voltage: 29v
Float voltage: 27v
Charge curve: adaptive
REC Q BMS balance V END: 3.58
Balance start V: 3.45
End of charge: 3.58
Current highest cell: 3.522v
current lowest cell: 3.516v
Right now there is only a couple watts indicated going in to this pack. This is a new setup and my first time working with BMS and LiFePo4. it's a 2p8s setup @ 400ah. Should this initial balance take a long time? It's already been over 24hrs like this and I don't want to damage my batteries. Any help would be appreciated.
One other question I sent in to REC as well is, does anyone know where to wire the contactor on the REC? All documentation indicates it is wired to the pre-charge unit but I did not buy one of these. There are two pins on the IO connector the pre-charge unit wires to but the reference to transistor legs on these terminals (1 & 2 - emitter and collector) has be concerned about I should be wiring this w/o the pre-charge unit.
Thanks,
Scott
The issue is once the REC switches the MultiPlus from bulk to absorb, it stops increasing the voltage when it reaches 28.3v. The current in to the battery drops to almost nothing and the Multi looks to be floating voltage at 28.3v while indicating it's still in absorb mode. If I remove the VE.bus cable from the Cerbo GX, it will stop charging after a few minutes.
I've tried a number of things but by testing has me currently at these values:
MultiPlus absorb voltage: 29v
Float voltage: 27v
Charge curve: adaptive
REC Q BMS balance V END: 3.58
Balance start V: 3.45
End of charge: 3.58
Current highest cell: 3.522v
current lowest cell: 3.516v
Right now there is only a couple watts indicated going in to this pack. This is a new setup and my first time working with BMS and LiFePo4. it's a 2p8s setup @ 400ah. Should this initial balance take a long time? It's already been over 24hrs like this and I don't want to damage my batteries. Any help would be appreciated.
One other question I sent in to REC as well is, does anyone know where to wire the contactor on the REC? All documentation indicates it is wired to the pre-charge unit but I did not buy one of these. There are two pins on the IO connector the pre-charge unit wires to but the reference to transistor legs on these terminals (1 & 2 - emitter and collector) has be concerned about I should be wiring this w/o the pre-charge unit.
Thanks,
Scott