Running battery poles to the trunk

[Rubigone]

Hello all,

I am looking to install some equipment in the trunk, a arb twin compressor, fridge freezer and maybe some extra lights in the future.

But instead of running everything independently i thought of just running two wires straight from the battery and making the little cubby under the boot a utility space with the compressor, two poles and a fuse box for attaching smaller accessories etc.

I understand that it all depends on what equipment is attached to the poles but the most amp draw this will see is the compressor and fridge running at the same time, maybe someone did this already and can share some experience on what gauge wire and what fuses (and where you fused) used in your project since I’m a bit confused on this subject.

Thank you in advance!

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[GATORB8]

I would recommend fusing at the battery, run a main back using total amperage to determine guage/fuse size, feed a small fuse box with that main so you can run as many circuits in the rear as you'd like.

EDIT: You only need a positive run from the battery. You can ground to the chassis/body.

 

[Rubigone]

I would recommend fusing at the battery, run a main back using total amperage to determine guage/fuse size, feed a small fuse box with that main so you can run as many circuits in the rear as you'd like.

EDIT: You only need a positive run from the battery. You can ground to the chassis/body.

Wow thank you for the graph, super helpful! Nice that i also need to run one wire instead of two, but i guess i need to locate a fat ground in the rear to connect to.

By looking at this I’d need to run just one 4awg wire with a 90 - 100 amp fuse in the front. Since the arb has twin 40 amp fuses I’d not want to pop the big one just the two smaller ones in the rear if the compressor overloads. Does this sound reasonable?

 

[mikej]

I ran 2 gauge for my similar project. It’s overkill and the size pretty much forces an exterior cable run, but I know I have all the capacity I need as a result.

For your fuse size, I’d keep the front fuse only slightly larger than any of your load fuses. A 45 (do they make those?) or 50 amp fuse would be a better fit. Carry spares and you’ll be in good shape.

 

[Rubigone]

I ran 2 gauge for my similar project. It’s overkill and the size pretty much forces an exterior cable run, but I know I have all the capacity I need as a result.

For your fuse size, I’d keep the front fuse only slightly larger than any of your load fuses. A 45 (do they make those?) or 50 amp fuse would be a better fit. Carry spares and you’ll be in good shape.

The problem is on the arb website they state a 68.6 amp max draw at 150 psi for the twin compressor which would pop the 50 amp relatively easy i guess?

 

[GATORB8]

The problem is on the arb website they state a 68.6 amp max draw at 150 psi for the twin compressor which would pop the 50 amp relatively easy i guess?

I've been out of the audio game for a while, but knukonceptz.com used to be a good value source for power cabling and accessories.

They have a super value line that uses CCA (copper coated aluminum) which requires larger size for the same equivalent AWG, but can be less than half as expensive. They'll also have fusing in the range you are looking for.

Another fuse option would be a marine circuit breaker.

 

[mikej]

The problem is on the arb website they state a 68.6 amp max draw at 150 psi for the twin compressor which would pop the 50 amp relatively easy i guess?

Wow, that’s a larger draw than I would have expected. 70 amp fuse it is, then.

 

[Gaffer]

Maybe not the same for automotive but in construction you use 125% of the largest load (amps) plus 100% of additional loads to select your minimum conductor size. Then fuse for the conductor size.

 

[Vanburi]

American adventure labs sells a wiring kit for mounting the arb in the rear cubby. Actually they sell mounts and brackets for this too...

 

[Rubigone]

Maybe not the same for automotive but in construction you use 125% of the largest load (amps) plus 100% of additional loads to select your minimum conductor size. Then fuse for the conductor size.

It sounds reasonable, which would be the following if i go by the table @GATORB8 posted.

arb twin ~70*1,25=87,5 amps
Dometic fridge ~9 amps
Total 96,5 amps

And this is a worst case scenario, with fridge freezing contents and the arb pumping up a tank to 150 psi simultaneously. The only other load i plan on putting is a led light for the trunk which shouldn’t draw anything close to 1 amp @ 12v.

It seems that a 4 awg fused at the battery with a 100 amp should be sufficient for the load and the length the wire will be ran. If I’m wrong someone please correct me

 

[Rubigone]

American adventure labs sells a wiring kit for mounting the arb in the rear cubby. Actually they sell mounts and brackets for this too...

Yes i know, i love their products they look so beautiful and well made and totally worth it, but with shipping and customs it will be almost double the price compared to the states which i can’t really justify, i will source it locally instead since it’s just some wires and bent steel.

 

[jaymz]

Ditch the fuse idea and use circuit breakers. 4ga is sufficient, but when running wire bigger is usually better. I’d use 2ga if you can.

 

[Rubigone]

Ditch the fuse idea and use circuit breakers. 4ga is sufficient, but when running wire bigger is usually better. I’d use 2ga if you can.

That’s true and seems reasonable, would be better to just disconnect the faulty electrical device and reset the circuit breaker and continue using the rest of the equipment incase it triggers, instead of trying to replace the fuse in the field. Thanks for the tip!

 

[Gaffer]

It sounds reasonable, which would be the following if i go by the table @GATORB8 posted.

arb twin ~70*1,25=87,5 amps
Dometic fridge ~9 amps
Total 96,5 amps

And this is a worst case scenario, with fridge freezing contents and the arb pumping up a tank to 150 psi simultaneously. The only other load i plan on putting is a led light for the trunk which shouldn’t draw anything close to 1 amp @ 12v.

It seems that a 4 awg fused at the battery with a 100 amp should be sufficient for the load and the length the wire will be ran. If I’m wrong someone please correct me

# 4 will be marginal

 

[OSCAR II]

The only problems with using larger cable is cost and workability. Voltage drop comes into play with length and with only 12v its noticeable. Go big, your appliances will thank you. Myself, on projects like this like to use marine grade cable. Its silver plated copper for corrosion and a better conductor. Its fine strand also and pretty flexible plus the insulation is weather rated and holds up well over time.
Its a little pricey but that what I do.

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