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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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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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