Multiplus 5000 gx with jk-bms parameter

[jeremc31]

Hello everyone,

I’m reaching out for your insights regarding an issue I’ve encountered with my current battery setup.

When my LiFePO4 battery reaches 100% State of Charge and transitions into float mode, my MultiPlus GX continuously cycles between charging and discharging the battery, rather than allowing it to rest — unlike my previous Pylontech batteries, which remained idle once fully charged.

Could this behavior be caused by an incorrect configuration on my part?

At the moment, my MPPT controller is set with a float voltage of 55.36V and an absorption voltage of 56.8V.

I would greatly appreciate your feedback and any recommendations you might have.

Thank you in advance for your expertise.

[lxonline (LX)]

Does it have comms with the system?

Is there a voltage difference between what the bms reads and the inverter and MPPT.

Are you grid connected or offgrid? Are you using ESS?

[jeremc31]

Thank you for your response.
Yes, the BMS is communicating correctly with the Cerbo GX, and the voltage readings seem to match on both ends.

I am connected to the grid and using the ESS (Energy Storage System) in AC-coupled mode.

[jeremc31]

[jeremc31]

[jeremc31]

[jeremc31]

[lxonline (LX)]

Hello, thank you for the configs.

Do you have feedback turned on and limited or a grid set point that is negative.

I have seen some push and pull from batteries before but not usually at 700W.

All i can think of offhand is there is an interaction with reactive power in the loads and power assist or something that is causing the movement

Maybe as another thing to check in vrm advanced is what the battery is requesting in terms of CCL and CVL

[lxonline (LX)]

Why is your battery monitor in ve config set to 150AH but in the JK it is 280AH?
I also think the voltage for smart sleep is a bit high.

[jeremc31]

@lxonline

Hello, thank you for the configs.

Do you have feedback turned on and limited or a grid set point that is negative.

I have seen some push and pull from batteries before but not usually at 700W.

All i can think of offhand is there is an interaction with reactive power in the loads and power assist or something that is causing the movement

Maybe as another thing to check in vrm advanced is what the battery is requesting in terms of CCL and CVL

Hello again, and thank you for the interest you’re showing in my issue — I really appreciate it, as I’ve been trying to identify the cause on my side without much success.

I have indeed set the export limit to 1000W (both AC and DC feed-in),
with a setpoint at 0%.

Regarding the 150Ah, you’re absolutely right — I’ll correct that, good catch.

As for the standby voltage, what value would you recommend?

[jeremc31]

on bms config

Vol cell rcv (request charge volatage 3.450 (55.2v)
vol cell RFV (request float voltage 3.500 (56v)

on Victron system
cvl 56v

on charger config
absoprtion voltage 56v
float voltage 54.8

on mppt config
absoprtion voltage 56v
float voltage 54.8