Finalizing camper cap build plans...need some final wiring guidance

Newbie here…looking for some help in developing plans for a shell camper. So far, I’ve decided the following:


1. I’m going to mount my house battery in the engine compartment

2. I won’t be using a power inverter so I’ll need several 12v plugs in the cap to power a vent fan, a small 12v table fan, LED lights, and chargers for my laptop and phone.

3. I’m going to get a 200 watt portable solar system and connect it to the house battery through the front of the truck grill when I need to charge the house battery.

4. I plan to build a shelf in the extended cab area for a fridge/freezer.

My wiring plan is to run power from the house battery for the fridge on the back shelf of the cab using a dedicated 12v plug, but would appreciate some guidance on how to run power to the camper shell from the engine compartment house battery. What gauge wire should I use? Where should I locate ground? Should I tap into the existing wiring that already runs to the shell, or is a dedicated run better?

Thanks, in advance, for your guidance.

SmokyJoe

 

ARB fridge pulls 1.3 Amps per hour (once cooled to temperature) Up to 5 Amp draw
Fan(s), most are around 3 amps
LED interior lights are usually around 0.5 amps each
Laptops around 3-5 amps depending on model

If something doesn't have an Amp rating, it probably will have an Watt rating. The math is [Watts/Volts]. So, in your calculator you put in the value for watts, press divide, put in the value for volts, then hit equals. If you put in Volts first you will get the wrong answer.

Say an LED light is rated for 13Watts. 13 watts /12 volts = 1.083 amps when running off of the battery. However, when the truck is running, and charging a battery, your alternator puts out 13.8 volts, so 13 watts /13.8 volts =0.94 amps. So really, just about 1 amp for a 13watt light.

Basically, you first need to know your power requirements, then you can determine wire gauge. Yes, you can go with a massive 3/0 gauge wire, but if you don't need that much it is an unneeded expense. Here is a handy guide that will help you determine wire size based on long the wire is and how many amps it can handle. Do not exceed these ratings or the wires can hot, or even catch fire.

 

That's EXTREMELY helpful, Thelgord...many thanks!