I use the following setup: ESS System with a Multiplus II 48V, CerboGX and a Lithium NMC battery that is protected by a built in BMS. The Multiplus does not communicate with the battery. Charging and discharging is controled by voltage.
I am currently testing the following settings:
System frequency 50Hz
Shore current 13.0 A
Overruled by remote unchecked
Dynamic current limiter unchecked
External current sensor connected (see manual) unchecked
State of charge when Bulk finished 100.0 %
Battery capacity 50 Ah
Charge efficiency 0.95
Country / grid code standard Germany: VDE-AR-N 4105:2018-11, internal NS protection
LOM detection AC input 1 Type B (grid code compliant)
rise-in-voltage protection U> 253.0 V
start network service HF treshold 50.20 Hz
P(f>) droop 5.00 %
Use Aux1 as disable FeedIn signal checked
Maximum AC current for charge or feed in 100.0 %
Reactive power regulation Use a fixed Cos Phi
Filter time for reactive power 3.3 s
Cos phi at point 1 1.00
Inverter output voltage 230 V
Inverter DC shut-down voltage 39.20 V
Inverter DC restart voltage 45.60 V
Low DC alarm level 45.60 V
Do not restart after short-circuit (VDE 2510-2 safety) unchecked
enable AES unchecked
Enable charger checked
Weak AC input unchecked
Stop after excessive bulk unchecked
Lithium batteries checked
Configured for VE.Bus BMS unchecked
Charge curve Fixed
Absorption voltage 53.00 V
Float voltage 52.98 V
Charge current 35 A
Repeated absorption time 0.25 Hr
Repeated absorption interval 45.00 Days
Absorption time 1 Hr
TAB: Virtual switch
Virtual switch usage Do not use VS
TAB: Assistant Configuration
ESS (Energy Storage System) (size:962)
*) System uses LiFePo4 with other type BMS
(This can be either a BMS connected via CAN bus or a BMS system in which the
batteries are protected from high/low cell voltages by external equipment.)
*) The battery capacity of the system is 50 Ah.
*) Sustain voltage 44.80 V.
*) Cut off voltage for a discharge current of:
0.005 C= 47.80 V
0.25 C= 47.20 V
0.7 C= 46.60 V
2 C= 46.10 V
*) Inverting is allowed again when voltage rises 1.20 V above cut-off(0).
*) Relevant VEConfigure settings:
- Battery capacity 50 Ah.
- PowerAssist unchecked
- Lithium batteries checked
- Dynamic current limiter unchecked
- Storage mode unchecked
Total size of all assistants including the required
(hidden) system assistants is: 1021
It works pretty well...
Now my question:
When there is enough solar to power home consumption the rest is used to recharge the battery. In bulk charge it all works fine, as soon as the absorption phase ends, the inverter discharges a little bit to reach the float voltage of 52.98 V. But then the inverter stays on (green light is on) all the time.... even though there is enough solar power to power the house and therefore the inverter not needed.
How do I have to change the settings in order to prevent this behaviour?
Or is there a way to completely disable float charge, as it is not useful for my type of Lithium-Ion battery?
Thanks in advance for your feedback and help!