@weejub thanks for your response, but I feel like I don't get it totally yet. I'm sorry but I have a couple of new questions.
1. Why would I want to add a new line from my alternator? And to what?
2. Alternator and switch (which switch?) goes to circuit breaker in upper right corner. I cannot see any switch besides from the circuit breaker.
3. No I understand why Bluesea would recommend a line from the alternator to the circuit breaker and on to the battery. But I do not understand why they recommend doing it from the starter.
Below I drew a schematic of how I understand Bluesea's recommendation. I don't understand it at all, so I'm sure that I am misunderstanding something!
My baseline for this drawing is that the circuit breaker can be used to switch between two conditions.
C1. Normal: Car battery is low and cannot start the car
C2. Emergency start: The extra batteries are connected to the car battery and can therebby assist on starting the car.
4. If I wire my system this way, I will be able to start my car only because there is a seperate line from the car battery to the starter. But if there is a permanent line between those, why is it then relevant to havea line between them through the circuit breaker too?
I'm lost here man, sorry about the bombardment of questions, hope you can help.