I agree with most of this drawing and part of what Creative is saying but I feel there is more to this as it does show what I feel can get us into trouble if we think of power as only going out of the converter!
It feels like a nit picking thing but one of the best tools we have is the human mind but it also is like any tool and we need to watch carefully that we keep it tuned and sharp!
So if we look at the drawing snip above, the item doing the charge, whether it is called converter, converter/ charger or only inverter, it is connected to the load center and batteries. I think we are all saying the same on that point.
When any spot is connected together like the battery, converter, and load center, they are considered the same electrically except for minor drops due to wiring resistance. All points in this yellow circle are considered the same electrically speaking. I think we can agree on that?
Where my nit picking is going is that we can fool ourselves if we think power can only go out from the converter output!
If we have a low battery like 10 volts and we go back to the converter output we will see ten volts at the output. If we are not clear on the nitpicking point, we can jump to the idea that the converter is only putting out 10 volts, so it must be bad!
NOT TRUE!
What we are seeing is not the converter output but the battery output!
So we may change out the converter and as we do we turn it on and we now see a good 13.5 volts at that point. Why the change? Did we do right and change the right part or did we just fool ourself?
We may have turned off the AC breaker feeding the converter while we did the converter change and now we have it turned on!
So was the converter really bad or was it as simple as the AC breaker was actually off but not tripped fully so that it showed off.
Just wasted a bunch of time, money and effort changing converters because we did not think of the converter output also being input from the batteries!
Yes, I will agree with the drawing that the output will only be output if we go inside the converter and get to the diodes, etc. but if we are testing at the points most of us will be on, power can be coming out of the converter or coming from the batteries!
I would mod the drawing to show as this?
One of the biggest follies on RV repair is when we take it to a shop, they find no power coming out of a board like on a frig and when they change that board all is fine, so we are told it was a bad board when it was really just a bad connection from corrosion not letting the board work but since the new board has new clean connections, it works!
Stay alert to save grief!