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schwuppe asked

Multiplus II Voltage Sense Error

Hello,


I had sent in my Multiplus II 5000/70-50 for repair but they did not find anything.


After it came back the device is behaving strange and often does not load the battery.


My setup:

The multiplus got the latest firmware version 507. It basically exists to store energy to a battery.
My venus os large installation an raspberry is on v3.20 and now on v3.21.

My battery is a 16S 280Ah system with Seplos BMS v2 10E, connected to the raspberry via RS485. Venus os detects it as SerialBattery(Seplos).

Grid meter is a 3 phase EM24 connected via RS485 to the rasberry.

Solar inverters are AC coupled and not known to the system.

I'm fetching data from Venus OS via MQTT interface.


-I tried with DVCC setting to on and off, since Seplos is not supported by Victron.

-ESS is active in mode Optimized either with or without battery life.


Inverter LEDs are of in the faulty case.


Then I get these entries in the log:

1708718504717.png

From the manual:


Voltage sense error. The voltage measured at the voltage sense connection deviates too much (more than 7V) from the voltage on the positive and negative connection of the device. There is probably a connection error. The device will remain in normal operation. NOTE: If the "inverter on" LED flashes in phase opposition, this is a VE.Bus error code (see further on).


Do I have to modify some settings? Or is the device defective and how can I make sure?

Multiplus-IIerrorvoltage
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3 Answers
Alexandra avatar image
Alexandra answered ·

@schwuppe

From what I have read on the forums the Seplos controls the system even when DVCC is off. It bypassed all that. Not sure how true it is since I dont have one.

But in ve config you can disable v sense for diagnostic purposes with the MK3. That seems to solve the issue.

7v is alot though. Probably the worst case I have heard of. Since you have ruled out volt drop over the cable (DMM reading on the terminals compared to the inverters own readings) it seems like a hardware problem.

There is a pre RMA document.

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schwuppe avatar image schwuppe commented ·

Thanks @Alexandra

What I did also is give MPII full control in the settings and to make sure also disable bus communication from the seplos BMS

1708786070626.png

After a reset of the venus os I get reproducible these 2 errors:

1708786160800.png

Masuring the battery termials with a multimeter at the MP gives me around 53V

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schwuppe avatar image
schwuppe answered ·

Today, after disabling Vsense the system is not workig properly.

-When disconnecting the BMS I got once this:

1708853282388.png

-ESS optimized with battery life seems to have a negitive effect on turning on battery loading at all, so I set it to optimized without battery life

-Battery SOC is now at 23%, MQTT .. /system/0/Dc/Battery/Soc gives me a value of 95% today

-Now it sometimes loads the battery a bit, most of the time not and never reaches the setpoint. The overall beavior seems random.

-And I got another

1708855475574.png



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nickdb avatar image
nickdb answered ·

If the system is configured with a BMS and it is unplugged, it will cause these sorts of issues.

Everything here screams a battery/BMS issue of some kind, you would want a shunt if it was disconnected as the system won't do a good job of recording SOC with any accuracy.

Problem or poorly configured DIY/unsupported batteries will cause these sorts of misleading errors and the multi will always bench test fine.

Victron recently updated its third party battery statements for this reason.



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schwuppe avatar image schwuppe commented ·
Without BMS the battery is a passive element with 16S balanced standard cells. How could this be the reason for a Voltage sense error ?
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Related Resources

Additional resources still need to be added for this topic

MultiPlus-II Product page 

MultiPlus-II Manual

Multiplus-II GX Online Manual

MultiPlus-II 230V Datasheet 

VE.Bus Error codes