Total Rewire - Trying to understand the process

So I ended up ordering a 45 amp 4 stage converter off Randy.

Just looking at my breaker panel inside the vehicle now, 30Amp is the biggest breaker I got. From what I I understand one of these breakers most likely powers my old charger but if I swap it out am I going to have to put in a bigger breaker?

I'm sure the guys that will wire it in will have the answers or I'll hunt down one of my buddies who knows this stuff but it's always to nice to know a little bit before walking into a mechanic.