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h-m-heating asked

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
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3 Answers
Paul B avatar image
Paul B answered ·

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


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alan avatar image
alan answered ·

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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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

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.

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h-m-heating avatar image h-m-heating commented ·

screenshot-20210120-232259-comandroidchrome.jpgI 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 VRMscreenshot-20210120-231753-comandroidchrome.jpg.

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