MultiPlus2 stops discharging. SoC never comes down to 10%

DIY
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1

Seeing MuliPlus-II warnings “Low battery voltage” evn the BMS shows cell voltage fare away from warning or alarm level.
When the warning chage to alarm status the ESS (I think) stops discharging and change to grid supply. This happens when SoC is in a range of 20-30%.
SoC is set to 10% in the ESS.

Edition: ESS mode is “Optimiert (ohne BatteryLive)” > “Optimized (without BatteryLife)”

2

Are you Ecentually running in “Self Consumption with Battery Health” mode?

Then the mininum soc will be increased based on days, where you don’t reach 100%.

So, the system then can use ranges from 100 to 60, rather than 50 to 10 all day.

Everytime you reach 100%, the effective soc limit will be lowered again.

3

ESS mode is “Optimiert (ohne BatteryLive)” > “Optimized (without BatteryLife)”

Thanks for feedback!

4

ESS mode is “Optimiert (ohne BatteryLive)” > “Optimized (without BatteryLife)”
Thanks for feedback!

5

@Alois
Check in MP2 VeConfigure of you activated Dynamic SOC and/or Battery Monitor.

1 Like
6

It is likely the dynamic cut off in the ESS assistant.

Check your voltage drop from your battery terminals to the dc terminal on the inverter.

7

There is a Lynx Shunt between the battery connetor and the distributor box. However I could not measure any voltage drop across the shunt. I wounder because a shunt is a resistor and the voltage across it is the measured parameter ??

8

Measure voltage at the inverter terminals, then measure it at the battery terminals - compare?
The shunt drop is for its own measurements.
Make sure you have correctly torqued and crimped all connections.
The other way to do it is to use the DMM on AC and measure voltage from pos to pos or neg to neg (one probe on battery terminal and one on the inverter terminal) and check voltage.
Its important to A. Be careful and B. Do so underload.
A third way is to use ve config and check DC ripple (under load)

9

Status:

  • SoC 43% Load ~8kW
    Battery: 49.5V MP2: 49.0V
    Load ~12kW >> Low bat alarm >> switch to grid >> Battery goes to more than 50V
    In any case DC cell voltage is more than 3V; no alarm from BMS all time
  • All connections are perfect!
  • Measure DC ripple to be done soon. Question: DC ripple is shown in ve config?
10

Just checked:
Load SoC 53% Load ~8kW
AC voltage (+bat to +MP2) 0.04V
Low Bat starts blinking at the MP2. Stop blinking when I reduce the load to 4kW.

11

What battery do you have?
Add your VE.config file or make some screenshots of your settings.