Dual battery first timer install advice

Thinking about adding a dual battery system in my 2013 dcsb with the sole purpose of powering a 12v fridge full time. Therefore, I wont include an inverter since I will only need the DC power for the fridge. And also my alternator is 130amp.

Was going to go with a 12V 30amp Renogy DC/DC charger with MPPT so I can add solar later down the line.

Im basing my numbers off this chart many of you have probably seen,
http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg

Im running wires from my engine bay back into the cab so I don’t think I will exceed 10ft there. Is there any incentive to use 4awg wire and say 90amp fuses for more safety? Or am I safe with what I currently have.

Im trying to wrap my head around how to do this in a simple way and I’ve made this drawing to how I think I would do it.

Please any input is welcomed.

 

Been along time since I wired in a dual battery but you should incorporate a battery isolater.

BTW On the linked chart, What is meant by critical and non critical voltage drop?

 

search "dual battery tacomaworld" on google, this has been covered extensively in great depth with tons of good setups over the past 20+ years.

 

For the length of your runs you should be fine with 6-ga wiring. absolutely do not put high than a 60A fuse on any of the lines. They specify 45-60A for a reason, it's to limit the amount of current able to go through the unit and the wires. Going with a higher amperage can cause problems.

Since the battery is going to be used exclusively for the fridge get a deep cycle battery as it'll hold up to the repeated charge and drain cycles you'll be having.

 

stock Alt can put out 130 amps max

400 watts is like 33 amps at 14v.

IxV=W

 

@majesticmilo, I used 6awg welding wire with a 50A breaker under the hood and a second 50A slow burn fuse between the charge controller and house battery (I'm using the Renogy 50A mppt controller so size your fuses accordingly if the 30A controller has different requirements). You want the fuse/breakers to be the limiting factor, not the wire or charge controller. I like having a breaker because it's very easy to isolate the house battery and wiring from the rest of the vehicle.

@1 Limited Toyota, the mppt is the isolator so there is no need to add one. The only time you'd need an isolator is if you are charging straight off the alternator with no charge controller.