Bump for this question!

I'm assuming this is the breaker I need? And I noticed an in/ out indicator on the breaker.. How do I know which wire goes to in and which to out?
Rockford Fosgate RFCB100 100 Amp Circuit Breaker

 

I wouldn't solder any of the connections, use high quality crimping instead.
That circuit breaker seems like it could work but I'm not certain that 100A is enough.
IN/OUT shouldn't really matter but I'm guessing battery connects to IN and OUT goes to engine/starter.
If you look at the picture on the package this seems to be confirmed.

 

There's a thread on here where the guy used a 150amp breaker. I'm trying to understand the purpose of the breaker if there's a 100amp fuse in the fuse box? I hate electric so maybe someone with a better understanding can shed some light

 

The breaker is like a reset-able fuse. A 100amp breaker will cut electric power if the current spikes over 100amps, theoretically you don't need the breaker, but more electrical protection is always nice.

 

So a 100amp breaker is sufficient since the fuse is a 100amp?

 

Our starter can easily draw over 400A for the first milliseconds when you push the start button, the stock fuse does not blow though but who knows how that breaker reacts.
Different types of fuses have different characteristic so it's very hard to tell which one will work without any data.

 

Gotcha so the beaker won't effect anything on the car, just an extra protection. If the battery sends more than 100amps for a period of time the fuse will pop.. Gotcha.. Ok just wanted to make sure I wouldnt be hurting anything but installed a not efficient enough breaker. Thanks guys

 

Breakers/Fuses do not react instantaneously. It takes some amount of time for the Current X Voltage = POWER to generate enough excess heat to trip the mechanism.

 

Gotcha, I hate electric so this is news to me haha

 

Forgot to mention, some circuit interrupters also work off the principle of magnetism. Though the trip levels are much higher. So a 100A thermal-magnetic breaker might trip at sustained 100A but would require a spike of 300A (just as an example) to trip magnetically.

I would use a breaker at whatever the stock fuse is rated for.