Strange Multiplus 2 48/3000 behavior out of the blue

Question

question

juniorpv asked Feb 23, '24

Strange Multiplus 2 48/3000 behavior out of the blue

I use a Multiplus 2 48/3000 with Cerbo GX and separate Li-Ion Battery, integrated via JK-BMS and control the system with Node-RED (Large OS).

While programming the control loop since 4 weeks (and optimizing) all was smooth (despite when I did wrong coding) ;-) .

However 4 days ago, out of the blue, the MP2 started to discharge the battery at full speed (as per MP2 unit config with 2.400 W). No idea why, and it took me a while to stop: Basically switched off.

In the meantime it happened 3 times again. No idea how and why, always after full charge, however not at peek, somehow delayed.

The node "Input power phase 1 (W)" "fires" the power out, I learnd to stop it by "VE Bus Reset" with "1".

I tried to implement a kind of "emergency break" using "VE.Bus Reset". Monitoring the output power and when above 2.350 W to send "1", during normal operation a "0" (as number) to "VE.Bus Reset". The result was a "not really working loop"/minutes between data flows.

Any idea why the Cerbo GX / MP2 get's the hick up ?

I use >ESS< with "Ext.Stg.", however I wonder why MP2 shows status messages "Bulk/Float".

Any idea to help circle the topic is welcome.

Multiplus-II cerbo gx Node-RED

1708703239175.png (43.9 KiB)

1708703307895.png (36.9 KiB)

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

147 People are following this question.

Modifications Space

Node Red Space

Answer 1 · 2024-02-24T14:58:41Z

juniorpv answered · Feb 24 at 02:58 PM

Okay, I found a workaround, but not solved the issue.

1. Fault description::

"Out of the blue", MP2 starts discharging (orange line) - at full power - in to the grid (green line).

2. First attempt to solve: In above function node "Notbremse P > = 2.350 W " I was writing "02 to "VE.Bus Reset", with the result of lagging a proper data flow:

As can be seen by the dotted values.

3. Then I changed "0" to "null". Now I get error messages.Which might be anoying to the system, but it's working:

The payload changes from null to "1" and VE.Bus get's a reset.

Okay, I fixed it, but I'd love to know the root cause, why MP2 "goes wild".

1708783950734.png (17.8 KiB)

1708784404345.png (12.1 KiB)

1708784498693.png (4.2 KiB)

2024-02-24-1526-3069.jpg (5.1 KiB)

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 2 · 2024-03-10T12:58:06Z

juniorpv answered · Mar 10 at 12:58 PM

Topic solved, I assume. Evenso I control MP2 via Cerbo GX setting "external Control", MP2 basic setting (VE Configure 3) takes at some point control.

I missed the point to set "Float voltage" equal to "Absoption voltage" (under Charger) to same value, using Li-Ion battery.

Hopefully I did right for now ;-)

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

question