Power to Rear Cargo Area

[Keith_Indy]

So I'm planning to run power to the back of the cargo area so I can run some accessories. These include a 12 volt fridge/freezer, Smitybilt air compressor, a 600W inverter, and a 12 volt fan.

Also in the mix is adding a 200 amp battery isolator, and an existing 200 amp alternator. One question I have is if all the 2 guage is overkill for the battery and starter connections?

The inverter is 1200W peak, which should be drawing around 100Amp(?). According to the wire gauge charts 4 gauge should be OK for that.

The fridge I'm looking at says it only draws 5.4 amps

The Aircompressor is either 30 or 45 amp max, so should that have it's own power too?

So I'm planning on running 4 gauge wires back to the inverter, the air compressor, and a 6 place fuse block. Below is a sketch of what I'm thinking.

Any advice would be appreciated.

current setup:

 

[4RunAmok]

First, lose the isolator. Isolators reduce the charge current by a lot, and the batteries will never get a full charge as a result.
Instead, use a hi-amp solenoid or automatic charging relay. These directly connect the batteries when they need to be connected and do not reduce the voltage from the alternator. Both of the links I'm showing here are for 100% Duty 500 Amp relays. One value priced, the other, well, it's up there, but not as up there as the outrageous dual battery kits out there.
http://www.amazon.com/gp/product/B001YIPXR2/ref=oh_details_o00_s00_i00?tag=5336653594-20
http://www.amazon.com/Blue-Sea-7622...&qid=1344668844&sr=8-1&keywords=blue+sea+7622

Second... I would more likely run the 4 gauge wire (WIRE, as in ONE) to the fuse block in the back, and then run my accessories to the fuse block... example

[MAIN BATTERY]----[ML-ACR or Soleniod]----[AUX BATTERY]----[150 AMP BREAKER]----(Long Run)----[FUSE BLOCK]====Accessories

This will greatly reduce your need for expensive 4G wire, reduce the hassle of trying to run a 2 inch thick bundle of wires through your interior or underneath your vehicle. And it just sticks with plain practical sense...

For example... If your Air Compressor is within 5 feet of your rear fuse block, a 10 gauge wire could support a TWO HUNDRED AMP draw over such a short distance. In fact, 12 gauge wire would support 100 amps on each wire to the fuse block. In other words, you are way over estimating your wiring gauges required. See this following chart for wire sizes:


You have a potential of 140 amp draw give or take with the accessories you've listed...So... 4G wire from the front of your vehicle, lets assume is 20 feet... can safely (easily) handle a 200 amp draw...
Then lets assume that each accessory is within 10 feet of the fuse block.
Fridge, 6 amp draw give or take (10 amp fuse in fuse block), only needs an 18 gauge wire
Air Compressor, 30 amp draw (35 amp fuse in block, or 50 amp breaker near compressor), only needs a 10 gauge wire
Inverter, 100 amp draw (120 amp breaker near inverter), only needs a 6 gauge wire

SIMPLIFY!...

You can get the awesome Cooper Bussmann resettable circuit breakers here at a good price! You can also buy all the wire you need on that site too.
http://www.powerwerx.com/fuses-circuit-protection/resettable-circuit-breaker-cooper-bussmann.html

I work with some pretty high amp stuff at work, we use Blue Sea products. If they can work on a boat, tumbling all over the place, in salt water environments, it's definitely good enough for our off road environments! Some examples of the stuff I make:


3 8D Batteries to power one very large inverter, mobile computer system, and an air conditioner.




In regards to your question about the 2 gauge wires up front, with a 200 amp alternator, I would say it's good. Besides, whats done is done, don't change it.

 

[pods8]

I'd also think running a single wire back would make the most sense, however don't look at it as what is the maximum a wire can handle you need to look at a reasonable voltage drop in the line so you're not under powering things. So for instance although 18ga can handle the amps you'd loose 7-8% of your voltage doing so where as 14ga would only loose 3%. That sort of thing to take into account so you're getting the right amount of voltage where you want it.

 

[Keith_Indy]

You have a potential of 140 amp draw give or take with the accessories you've listed...So... 4G wire from the front of your vehicle, lets assume is 20 feet... can safely (easily) handle a 200 amp draw...
Then lets assume that each accessory is within 10 feet of the fuse block.
Fridge, 6 amp draw give or take (10 amp fuse in fuse block), only needs an 18 gauge wire
Air Compressor, 30 amp draw (35 amp fuse in block, or 50 amp breaker near compressor), only needs a 10 gauge wire
Inverter, 100 amp draw (120 amp breaker near inverter), only needs a 6 gauge wire

SIMPLIFY!...

...

I work with some pretty high amp stuff at work, we use Blue Sea products. If they can work on a boat, tumbling all over the place, in salt water environments, it's definitely good enough for our off road environments! Some examples of the stuff I make:

Thank you so much for your advice. That is exactly what I'm looking for, and I've attached a copy of my new plan.

The blue sea 6 position fuse block is the one I'm using, and I'll be getting one of their ACR's forthwith. I'm using 2 gauge front to back because at some point, I'll be installing rear lights, probably a winch, and powerpole connectors to provide a place to jump start other vehicles. Also I'll be covered if I need to upgrade the inverter. I already have spools of 4 and 8 gauge wire so that's no problem.

BTW impressive work you do there...

 

[4x4junkie]

That looks like a lot better plan to me also.

Just make sure your ground up under the hood from the frame to the battery(ies) is good & strong using the same size wire if you're using the frame as your return path (an inadequate ground can create multiple issues in the vehicle's other electrical systems with that much current going through it, not to mention the additional voltage loss).

pods8's advice is very good too. You don't want any more than about 4-5% voltage loss @ full current back there (the less, the better). #2 ga will probably work ok for the main run, though if it were my setup, I'd use #0 ga to get the juice to the rear... A short run of #4 ga is good from there to the inverter, #8 or #10 for the compressor, all the rest I wouldn't use anything smaller than #12 ga regardless of the load.

A good page for calculating the voltage drop across various size conductors:
http://www.nooutage.com/vdrop.htm
13' of #2 ga will have right about 5% loss at 140 amps, where #0 (1/0) is closer to 3% loss.

 

[4RunAmok]

All great posts.

With regards to the ground, as a general rule, do not rely on frame grounds on long runs, run a ground wire of equal size back to the battery.

As 4x4Junkie said, you can jump to the next larger size wire than required to prevent voltage drop. And looking back on my post, while you could "get away with" an 18g wire on the fridge, I agree anything smaller than 12g is weak.

As for running a winch on the rear, I advise that 2g wire is too small for a full length run to power a winch. You will want to run 1/0 (one ought) or even 2/0 wires exclusively for the winch from the batteries. Do not use these wires to power the system in the rear, and put proper protection (fuses) at both ends of the run.

 

[Keith_Indy]

All great posts.

With regards to the ground, as a general rule, do not rely on frame grounds on long runs, run a ground wire of equal size back to the battery.

As 4x4Junkie said, you can jump to the next larger size wire than required to prevent voltage drop. And looking back on my post, while you could "get away with" an 18g wire on the fridge, I agree anything smaller than 12g is weak.

As for running a winch on the rear, I advise that 2g wire is too small for a full length run to power a winch. You will want to run 1/0 (one ought) or even 2/0 wires exclusively for the winch from the batteries. Do not use these wires to power the system in the rear, and put proper protection (fuses) at both ends of the run.

Thanks for the advice, I'll leave the 2g wire for the accessories and run a new wire if/when I get a winch in the back.

 

[El Solis]

I did just this, ran 2/0 wire to the rear. Split it so as to branch to the compressor and then to the fuse box.


Used waterproof glans for the in/out of wires


And used weatherpack connectors so I can remove the box easily if I have to.

 

[ldivinag]

Thanks for the advice, I'll leave the 2g wire for the accessories and run a new wire if/when I get a winch in the back.

if you plan on running a winch in the back, 2g will be a little small.

ok... when i built my removable winch setup, i wanted overkill. back then (10+ years ago), 2/0 gauge was cheap from a local welding supply house. so i made a "jumper cable" using 2/0 cable and 350 amp anderson powerpole connectors...

 

[wrcsixeight]

A fridge which draws 5.4 amps is likely powered by a Danfoss bd35f compressor with a resistor in the thermostat circuit to increase compressor speed to 3000 rpm.

Danfoss compressor controllers are finicky if the incoming voltage is too low. So oversizing the wire to minimize voltage drop is good preventative medecine.

Danfoss also says not to share the wiring with a common buss or fuse block, but to wire the power leads right to the battery fused as close to the battery as possible.

Since the Danfoss compressor controllers are a minimum 200$ to replace, I would follow their instructions to minimize possible damage caused by sharing the wiring with other devices and run dedicated wiring right to the Aux battery for just the fridge.

 

[Mel.Specs]

Anyone with knowledge or experience?

Does anyone have any knowledge or experience with this cable. I have about 50' of it sitting in my garage. I am wondering if this cable would be sufficient or overkill to run power to the rear cargo area. (Same set up as OP)

What I found online is, it's a shipboard cable rated for 600 volts. I'm assuming (1979) is manufacture date. I also heard it is equivalent to 2g cable.

Thanks

 

[4x4junkie]

Is it copper? What is it's diameter? (#2 AWG conductor would be a bit over 1/4" diameter, maybe 5/16" if stranded).

 

[Mel.Specs]

Is it copper? What is it's diameter? (#2 AWG conductor would be a bit over 1/4" diameter, maybe 5/16" if stranded).

Yes, it's copper.

 

[4x4junkie]

Looks like it might be around #4 AWG. May as well try using it since you have it. If you're running an inverter and it's not quite delivering enough juice (inverter kicks off near full load), you can always double it up. Definitely not overkill unless all you have back there is a fridge and a couple cig-lighter sockets (in which case #10 would be fine)

 

[Mel.Specs]

Looks like it might be around #4 AWG. May as well try using it since you have it. If you're running an inverter and it's not quite delivering enough juice (inverter kicks off near full load), you can always double it up. Definitely not overkill unless all you have back there is a fridge and a couple cig-lighter sockets (in which case #10 would be fine)

Thanks! I'll give it a shot.