Multiplus II 48 v 5000kva / 70 shuts down - Overloads with weak grid

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h-m-heating asked Jan 16, '21

Multiplus II 48 v 5000kva / 70 shuts down - Overloads with weak grid

We have been having problems with an Inverter shutting down every few days since installation, we have updated the Firmware on GX, Solar Charger, the Inverter and the BYD battery but still it continues.

The Grid voltage is erratic which is why we installed this system so that we could have a reliable supply, but it has been anything but reliable and the client is becoming concerned.

There is no one at the property so the battery is running between 90% - 100% all the time but I have noticed that the Victron system is reporting Overload and low battery with around only 40w – 75w load on the system, the batteries do not trip off and only requires the Inverter to be switched off and on again to get it to start working again which will sometimes run for a week or two without problems.

I have increased the Grid disconnect voltage so that the voltage does not drop to far before the Inverter takes over the supply, I have also tried adding Capacitors to the DC side to smooth the DC voltage to try that but that did not improve the running either.

I need to know is this just a problem with the Multiplus II or would the older Multiplus also do this?

Is it possible for Victron to login to look at this system?

Multiplus II 48 v 5000 KVA

BYD 14.5 kwh Lithium Battery

Smart Solar 150/70

GX running ESS

Multiplus-II

2 |3000

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Modifications Space

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Answer 1 · 2021-01-17T06:02:34Z

Paul B answered · Jan 17, 2021 at 06:02 AM

Have a close look at the batterys BMS history as it maybe disconnecting from a hi voltage cell reading.

ie if it disconnected

then the solar would keep the inverter up then if you got a high draw of power the inverter would see LOW voltage and or overload due low voltage as the battery was off and the solar could not supply the load.

it only has to be one cell in the bank that's out of balance and you will get this issue. you should have VRM access to you can see it happening when the volts are high and the battery current drops to zero then on again (low amps) then off, and the cycle repeats.

after 3 convective overloads then the inverter stays off until a manual reset is done.

a overload can occur at low voltage as well.

anyway this is a best case guess that MIGHT help ?????

below is one of my sites doing it with the gen running. then the gen would turn off and we would get low battery warnings or shutdowns just as the gen turned off as the batteries were also turned off by the bms

1610863752613.png (58.4 KiB)

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Answer 2 · 2021-01-18T03:41:42Z

alan answered · Jan 18, 2021 at 03:41 AM

Sporadic overloads were fixed in a very recent firmware, late last year.

Otherwise it may be worth looking at what hardware revision it is. See link

https://powerforum.co.za/topic/4347-victron-behaviour/page/2/#comment-63697

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Answer 3 · 2021-01-18T08:52:22Z

Guy Stewart (Victron Community Manager) answered · Jan 18, 2021 at 08:52 AM

hi @H M Heating,

As mentioned, the latest VE.Bus firmware version 478 - includes fixes for spurious overloads.

Fixes include:

Prevents permanent lock on ripple error due to overload.
Improvement of acceptance of grid in “floating phase” systems icw generators.
Solved: Spurious switch off due to overload.

Available on VicProf and the firmware dropbox now for manual update; and will be included in VictronConnect a while from now.

Any and all strange issues related to overload should first update to this firmware version, and then follow normal overload investigation if they are still occurring.

You don't mention the current firmware version in your post, you can find it by looking at the device list for the site in VRM.

10

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h-m-heating commented · Jan 28, 2021 at 03:39 PM

I have been running the update 478 for 10 days and I am sure it was better, but yesterday the Multiplus 11 shut down again, with just overload LED showing, the load on the system is very low, just swittich the Inverter of and on again makes it start again OK, I have also noticed low battery light flashing at times when the battery is almost 100% SOC on the VRM.

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h-m-heating h-m-heating commented · Jan 28, 2021 at 03:45 PM

This could be unrelated but I have just recently set the system to feed surplus power back to the Grid when the Battery is full and I am getting (Error code: #28 - Charger issue with power stage), would you have any ideas about this, it does seem to clear on its own then comes back again?

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Guy Stewart (Victron Community Manager) ♦♦ h-m-heating commented · Jan 28, 2021 at 06:25 PM

Thanks for reporting.

Is it possible to please revert to the previous configuration of no feed-in to see if that resolves system stability?

Also can you confirm that the system does not restart on its own, and requires a manual power cycle?

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h-m-heating Guy Stewart (Victron Community Manager) ♦♦ commented · Jan 30, 2021 at 05:26 PM

Hello Guy

Thanks for coming back to us.

We have put the system back to no Grid feed in for the moment to see if it behaves it's self.

With the Grid feed in the we had to manually cycle the power to get it to restart.

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h-m-heating h-m-heating commented · Feb 02, 2021 at 12:27 PM

Hello Guy

We are now convinced that the 478 update does work OK without problems, however what can now be done about the Inverter shutting down when we feed the surplus Solar Power back to the Grid once the Battery is full?

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Guy Stewart (Victron Community Manager) ♦♦ h-m-heating commented · Feb 02, 2021 at 12:35 PM

It could be a hardware issue, please get in touch with your supplier and report the fault to them to see what can be done.

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h-m-heating Guy Stewart (Victron Community Manager) ♦♦ commented · Feb 14, 2021 at 07:26 PM

Hello Guy

We have had one Overload shutdown since the 478 Firmware update, I still don't understand how we can see warnings and alarms for Low Battery and Overload when the maximum Load during the Day is less than 100 watts with almost 100 SOC ?

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seb71 h-m-heating commented · Feb 14, 2021 at 09:24 PM

They released FW 481 in the meantime.

From the firmware changelog:

"February 9, 2021

False overloads proved still to be possible. A cause for this has been found and a solution is implemented to prevent this."

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Guy Stewart (Victron Community Manager) ♦♦ h-m-heating commented · Feb 14, 2021 at 10:02 PM

As mentioned by @Seb71 - There has been additional fixes for this issue made in the new 481 firmware, so please update to that and see if things are improved.

On top of that, the SOC has no relationship to the low battery warnings, those are driven by battery voltage, and while SOC is a useful metric, it should not be considered a reliable one in comparison to battery voltage (and battery voltage response to charge or load currents) when doing a troubleshooting diagnosis.

Please try the new firmware now though.

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h-m-heating h-m-heating commented · Feb 14, 2021 at 10:13 PM

Battery Voltage for the same day

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dc-voltage.png (25.0 KiB)

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