Hello again,
I’m after few more tests right now.
I also modified the installation inside the car battery box.
Now i’m using recommended fuses (midi) by you. It looks like that:
Firstly i connected all orions without a fuse at all in car battery box. And I recorded the behaviour on voltmeter.
I was using Engine Shutdown Detection to Off.
I saw, that Voltage measured from car battery is growing until it gets above 14V, and then (i guess) that orions start charging, and voltage is dropping until 11,6V. Then it resets and is growing again to above 14V, when it reach above 14V - then orions start charging and voltage is dropping again below 12V.
All the tests were performed without a fuse on car battery side (cables screwed).
First tests was performed with Engine Shutdown Detection disabled at all:
the second test was with engine shutdown detection ON and shutdown voltage set to 12.8V: (this test shows that it is stable on 13.1V to 13.2V on the car battery side during orions charging).
Here is how orions are connected to the auxiliary batteries: (I will replace the fuses to the recommended midi ones on this side also - but I will do it in next week - I have to order them)
Thanks in advance for help 
Regards,
Matt