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hank73 avatar image
hank73 asked

Multiplus-II 48/3000 AC In Fuse trips when no battery connected

When I operate the Multiplus from 48V battery, it works without a problem, and when I then apply 220V to AC-In, it synchronises properly and switches smoothly from Inverter to mains supply.


I tried powering the Multiplus from AC-In with no battery connected. After a few seconds the Multiplus causes a short circuit or overcurrent and trips a B16 fuse/breaker.

The manuals says, the input should be protected by a 32A breaker, or with a circuit breaker suitable for the wiring. In my case this is 16A.

Is the inverter broken or is that expected beviour?


Best regards

Hank73

Multiplus-IIfuses
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netrange avatar image netrange commented ·

WHY you tried powering the Multiplus from AC-In with no battery connected ???

The Batteries has to be connected to the Multi ... It is a Battery based Inverter ...

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hank73 avatar image hank73 netrange commented ·
Where can I read that a battery has to be connected?
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wkirby avatar image wkirby ♦♦ hank73 commented ·

You can read that in the manual section 4 - Installation.

4.1 - Location
4.2 - Connect battery cables
4.3 - Connect AC cables

Installation section on page 9: https://www.victronenergy.com/upload/documents/Manual-MultiPlus-II-12V-24V-48V-3k,-5k,-8k,-10k-230V-EN-NL-FR-DE-FI-SV.pdf

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hank73 avatar image hank73 wkirby ♦♦ commented ·

This Victron video says, it can be connected to either through the ac input or dc supply or battery. Have they ever tried this with a Multiplus II 48/3000??

https://www.youtube.com/watch?v=6lH3mF2cVaY


The default settings of the Multiplus do not fit for all type of batteries. The charger is enabled by default and the battery settings are for a 48V AGM battery, not for a 15s LiFePo battery. The Multiplus will try to overload it.

So it might be useful to configure the device before operating it.

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nickdb avatar image nickdb ♦♦ hank73 commented ·
Arguing with experienced installers and users isn't helpful.

Victron products are meant to be installed and configured by qualified people. It has to be properly setup at the start for your environment, it will not work properly out of the box. Anyone experienced with the platform can tell you this.

Inverters are not plug and play.. get yourself a good installer to help.

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hank73 avatar image hank73 nickdb ♦♦ commented ·
Yep. Connecting an inverter is really rocket science.
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markus avatar image markus ♦♦ hank73 commented ·
Thank you for this sentence. In the context of this thread, it is really worth a smile.
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ hank73 commented ·
To prevent overcharging the batteries just don't connect the AC IN until you configured the MultiPlus.
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hank73 avatar image hank73 Matthias Lange - DE ♦ commented ·

Ok, let me recap this:

When I power Multiplus with AC without battery, empty battery or blown battery fuse, this will cause a "boom". This should be avoided but is normal behaviour for a Multiplus.

Thank you. That's all i wanted to know.


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Ingo avatar image Ingo hank73 commented ·

But you CAN start the Multi without a battery so that it per-charges the capacitors. I do it all the time. Failing that you need the previously mentioned pre-charge resistor.


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1 Answer
Alexandra avatar image
Alexandra answered ·

@hank73

To be expected. The capacitor bank in there is a mother amperage draw on first connection. And I second the why no battery when its purpose for existing is the battery?

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hank73 avatar image hank73 commented ·
There are ways to limit inrush current in ac and dc systems.

In my case it was testing after i had re-wired the ac connection. The battery was not connected yet.

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Alexandra avatar image Alexandra ♦ hank73 commented ·

On the DC system you can with a resisistor, or if the battery has a precharge circuit. If you had a battery connected there would not be inrush every time it was connected to AC.

The default settings are fine for initial start up and connect to dc (battery) as long as there are no charging sources attached while you are trying to program it.

I usually connect to battery and solar, with PV disconnected, program the unit then do the AC wiring section.

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hank73 avatar image hank73 Alexandra ♦ commented ·

Good to know. It would be worth giving a hint in the manual. Something like "Do connect AC to the Multiplus without a battery connected".

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Alexandra avatar image Alexandra ♦ hank73 commented ·

It is a sort of given understanding considering the connection procedure in the manual? And the fact that it is a DC based system not AC and all its programming is related to DC. Or at least in my mind it was. All the online training shows DC connection before AC as well.

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