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Simon Fey avatar image
Simon Fey asked

Multiplus 2 GX restarts when External Control setpoint cannot be reached.

Dear Victrons,


I experience restarts on a Multiplus 2 GX (3kW) when I use external control via Modbus TCP.

I have a battery connected that (in some situations) cannot provide the power that is requested by a setpoint via Modbus TCP.


Steps to reproduce:

- Connect a battery that provides only 1kW in charge/discharge to DC/48V

- Provide a setpoint beyond -1kW or +1kW for about a minute

--> System restarts


I am running an early 2.80 GX Firmware with Multiplus Firmware v494 and ESS with external control enabled.

I do have a BlueSolar MPPT attached with VE.Direct


Is this a known issue? Or even a safety feature?


Thank you very much!

Simon


Multiplus-IIModbus TCP
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3 Answers
markus avatar image
markus answered ·

May I ask you a question about another topic, not electricity related?:

What do you expect, if you equip your car with a fuel pump, only capable of delivering 1/3 of needed fuel to the engine and go full throttle?

The answer to this might be a comparable situation, that should bring an answer to your question as well.

BR

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Simon Fey avatar image
Simon Fey answered ·

Hi @Markus, thank you for your reply. I would expect any sort of error message. Right now I am stuck with arbitrary reboots with no logs and a vague assumption. Can you confirm that this is an intentionally wanted system behaviour by Victron?

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markus avatar image markus ♦♦ commented ·
Well, yes. This is intended behavior.

I assume, you may have a Lithium battery, equipped with a internal BMS. If you overload the battery, the BMS will just cut off the Multi from the battery.

But your logs (on VRM) should show low battery warnings, or high DC ripple warnings.


If you have a intelligent CANbus battery, the battery will dictate the system it's max charge or max discharge currents, as long as you are running grid parallel only, those limits will be accounted and your grid setpoint (if greater than max. possible battery power) should then not be reached and the system should not switch off.


BR

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Simon Fey avatar image
Simon Fey answered ·

Just to sum things up - I managed to solve the problem with the help of the following posts:

Ripple shutdown? Quattro 48/5000, offgrid, 100ah LifePo4 battery - Victron Community (victronenergy.com)

Multiplus-ii ESS, cycling export-import behavior, high dc ripple - Victron Community (victronenergy.com)

"I ended up lowering my absorption voltage lower (56.2) and it solved the problem."

This also solved the problem for me.

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