Aux power/fuse box in rear cargo area.

[KLAKEBRONCO]

I have the rear interior panels out to fab new ones. I'm also going to Por 15 the interior, and add some peel n seal insulation before either putting the vinyl floor back in, or finding a carpet set.

I'd like to wire in a fuse box and mount it in a compartment in the rear interior panel.
I have some push on/off lights, and a 12v power source to hook up. But I'd like the ability to hook up other accessories back there.

Is a 4 gauge wire thick enough to run from the rear of a fullsize bronco to the battery? I have some of that size in red and black that is long enough to reach. Just need a small fuse block.

Any other tips? I'd also like to wire in a power inverter. Nothing huge. I have a 300 watt unit now, but would like to replace it with a 750. Again nothing huge. I would like to use the smaller unit for now, but have wires heavy enough for the larger unit.

 

[LandCruiserPhil]

A 750w inverter draws around 60A + fully loaded. Depending on how long your run of #4 is will determine if you will be able to run your inverter. Also your engine running when using the inverter will help a lot.

 

[shogun]

Just did that job.

A Painless 7 circuit block is rated around 80a total and each circuit is 10a fused. So really 70a, IF you run all at max at same time (unlikely). So for estimate figure 80a.

I ran about 25' of 8awg which is really overkill for that, could have easily used 10 or even 12awg for that load and distance. There are some recommendations on sizing if you search. I wouldnt waste the copper on a 4awg. You might want to run the inverter on a seperate line of it really pulls 60a.

 

[R_Lefebvre]

12V wiring sizing isn't so much concerned about the absolute maximum amperage capacity of a wire the same way AC wiring is. For 12V, what we're really concerned with is voltage drop. We don't have 120V to work with, so losing even 1 volt is a big deal. A good target for 12V wiring is 0.5V drop.

Your 750W inverter will draw 62A if it was 100% efficient, which it's not. So, lets assume 80A. Then if we add a few more amps for your lights and 12V source, so we'll assume it could draw 100A max.

Using a handy resistance calculator here:

http://www.cvel.clemson.edu/emc/calculators/Resistance_Calculator/wire.html

And knowing that V=IR, we can calculate voltage drop.

V=100*0.004 (for resistance of a 15 foot length of 4 ga.)

V=0.4V

So, voltage drop of 0.4V. Not bad, and sounds reasonable. You can play with it from here.

As for running 80A, 25' of 8ga would be 1.28V, and 25' of 12ga is 3.2V. I wouldn't be doing that on my truck.

 

[overlander]

This is what I did, running single 10awg line to a marine fuse bus (with an integrated neg bus) to the engine compartment and rear cargo areas. keeps things much cleaner and MUCH easier to add future accessories, as well as troubleshoot electrical issues. I have a 1500 watt inverter that is wired seperately using 4awg to the aux battery. I chose 1500 watts to have short term emergency capacity for the unseen. 400 watts is more likely sufficient for what I would normally use if ever. Both inverter and aux fuse panels are fused near the source and all tied into my aux battery.

I think 4awg for a fuse panel is overkill for distances of around less than 10 feet. I also think you should wire your inverter separately and directly to the battery.

 

[KLAKEBRONCO]

I think I'll run the 4 gauge through the interior, and install it to a power dist block. Then hook up the inverter to the block, and hook up an aux fuse center with smaller gauge wire.

This sound reasonable?

 

[overlander]

I think I'll run the 4 gauge through the interior, and install it to a power dist block. Then hook up the inverter to the block, and hook up an aux fuse center with smaller gauge wire.

This sound reasonable?

That sounds like a good idea to me.

I put a marine 150amp circuit breaker on my inverter at the battery source before the 4awg connection to my inverter. I recommend you do the same with your setup even if you split it. Don't need to find after miles of off road travel, that vibration has worn through the sheath of the 4awg, with no protection between the chassis and the copper wire. That's a disaster waiting to happen.

 

[BlueGerbil]

For power distribution and fuses I just bought that: http://bluesea.com/products/5026

It really helps cleaning up that wiring mess. I put it in the glove box and will perhaps mount a small one in the rear of the vehicle.

 

[AZUnlimited]

That sounds like a good idea to me.

I put a marine 150amp circuit breaker on my inverter at the battery source before the 4awg connection to my inverter.

This is a very critical point. Make sure to fuse the wire at the battery. The fuse should be properly sized to the cable.

 

[kjp1969]

If you have a factory towing harness, you probably already have a switched (engine on only) and beefy charge circuit wire already run to your 7-pin connector at your rear bumper.