Hello, I have a new installation of 3 48/8000 and want to setup a 3phase system.
To test everything befor making all the big Cabliing, I created a test Setup where I connected only AC-In and the VE.Bus. For the test Setup, hthere is no Load and no Battery connected yet.
I wanted to setup the config and see if all devices are communicating correctly. So after FW upgrade and the 3Phase setup using the CerboGX and remote Ve.Configure where i assigned each phase to one Multi, everything looked fine until the system restarted.
After the Multi started up, they at some point swich some
Relais internally and everytime they do that, immediately my circuit breacker blows.
In the Test Setup i used a 16A breaker and ecpected as no loads is on the Multis, this would allow me to get things started. Why is my breaker everytime blowing when the Multis start??
o test everything befor making all the big Cabliing, I created a test Setup where I connected only AC-In and the VE.Bus. For the test Setup, hthere is no Load and no Battery connected yet.
WHY 
… read the Installation Manuals … ALLWAYS WITH A BATTERY
Hello Steffen, this does not make any sense. If this was true, and the Batteries must be connected at all times, otherwise the Multis do not run, then this would mean that in case of a Battery maintenance or error, the entire House would go dark.
I hardly belive that this is the case…
The Multiplus ALWAYS need Battery!
It is fully normal to blow the LS when there is no Battery.
You would install a bypass switch for maintenance/repair. That is just good design.
Hi Steffen,
It seems that many people believe the MultiPlus II cannot be operated without a battery. However, I have thoroughly reviewed the entire manual and found no indication of such a statement—neither in the boat/car setup nor in the ESS system.
Additionally, even Chat GPT couldn’t locate any such statement. I’m always open to learning something new, though! 
Would you mind sharing your source for the above statement?
Kind regards
Swen
there are several factors …
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this ‘mistake’ has been made for ‘years’ … if you had used the search function, you could have read this yourself. But I admit that since the old forum was closed, many topics have been virtually lost
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the Multi is a ‘battery inverter’ and not a mains inverter … it needs the battery for ‘initial commissioning’ as this is its Basic supply, so to speak
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it also works without a battery for initial commissioning … BUT then you need a power supply unit with the necessary voltage supply to charge the capacitors on the mains board.
Hi Steffen, now it makes sense.
Thanks for your support and time.
Regards Swen
Glad someone was able to explain in a way you understood.
I am adding to this post so that anyone else looking can have further information
I do have some questions as to how a battery was not implied/expected as its base?
On the product page it is described as an inverter charger. It does not have pv connection so it can only be inverting from the battery as dc source.
Speaks of how a battery is both used and charged in its power assist feature on the product page. And has UPS functions - all ups’ have batteries.
And is the first thing described in the manual to connect in Installation, second is ac cabling.
Hahaha