Battery isolator functionality question

[Firstascent]

I have a question about battery isolators I haven’t been able to find an answer on. I understand it’s purpose and function under normal use/wiring, but I’m wondering if there is any functional difference to my simple wiring schematics below.

from what I can see, batteries would still be isolated and everything would function the same way. From the alternators perspective, it doesn’t know the difference.

am I missing something, or would you agree these are functionally the same?

thanks!

 

[rodrick]

When the alternator isn’t running the battery becomes the power source supplying power to the input and any draw on battery 1 will pull battery 2 down

 

[Samsonite801]

That isolator might look something like this inside (without the charger switch in the circuit):

 

[Firstascent]

When the alternator isn’t running the battery becomes the power source supplying power to the input and any draw on battery 1 will pull battery 2 down

Oh yeah, duh I don’t know why I didn’t think that battery 2 would then become the source and they’d no longer be isolated.
It’s so obvious once I read your post haha, thanks!

 

[wme]

I did what your suggesting with a solenoid isolator. I connected the house battery to the alternator to get every last possible erg of energy into the battery. The engine battery was happy at a lesser charge.

 

[Firstascent]

I did what your suggesting with a solenoid isolator. I connected the house battery to the alternator to get every last possible erg of energy into the battery. The engine battery was happy at a lesser charge.

Thanks! Most solenoid isolators keep them disconnected until the engine is running then it connects them (ie via accessory signal or similar).
I want the batteries to stay isolated 100% of the time but to both charge from the alternator.

My original thought process of tying one battery to stay directly connected to the alternator is that the Victron isolator I was looking at has a max output of 200a, my alternator is a 280a so I didn’t want to limit the current.