I want to use an audio amplifier in my trunk.

That's why I want to pull two thick wires from the car battery that's in front.

I've tested and worked only that wires are pulled through the outside of the car.

 

This is not best practice, but if must, be sure to include a fuse right at the battery.

Otherwise you might burn your car down to the ground.

 

I want to use an audio amplifier in my trunk.

That's why I want to pull two thick wires from the car battery that's in front.

I've tested and worked only that wires are pulled through the outside of the car.

Did this on my wife's Jeep for her amplifier. Make sure you use wire rated for the maximum current the amp can draw with some headroom. For example a 12 volt 500 watt amplifier can draw over 41 amps so with an allowance figure 50 amps. I used AWG 6 (4.12 mm) wire and fused it at the battery using a 50 amp fuse. Make sure the wire can handle the fused current limit. Also it is wise to use high quality copper lugs for your battery connection(s) and amplifier.

Ron

 

If you do a bit of digging more than likely your vehicle had one or more unused passthrough ports in the firewall that just have rubber plugs in them or one that has only a small wire loom set in it but lots of extra room around it to be able to add a hole for your power wire. Find one and drill a properly sized hole through it and run your wire through there. Just be sure to get more wire than you think you need being doing such firewall pass throughs can eat up way more lengths of wire than you think they will due to the too often less than ideal path the heavy wire may end up following.

I've done many where the distance from the battery to amplifier looked to be less than 15 feet but used up closer to 25 feet before everything was in place and secured.

Also as other mentioned putting a proper primary fuse on the line is highly recommended.

 

If you pass your cable through a metal hole, be sure to use some sort of grommet so the metal doesn't cut through the wire insulation over time. Every car is different, you're going to need to poke around and find the best route in your car. If you go under the carpet, be very careful to avoid pinch areas, such as near seat mounts,
under where peoples feet go, etc.. Over time, pressure can squish the wire hard enough that the wire comes through the insulation, shorting on the frame of the car. As mentioned above, put an appropriate fuse as close to the battery as possible.

 

Car audio brands make a lot of money selling massively overpriced copper cable wiring kits.

Just buy welding cable instead, it's the same thing

 

Plus 1 on using grommets if you go through any panels. Don’t think it won’t matter, it will cut the wire eventually.
Go through the route you want to take with string first, then tie the cable to the end and feed it through. It’s easier to change the string path if you have problems, than it is to try and pull out all the cable and find another route.

 

Why pass DC ? You could pass 500 volt at 100kH with regular AWG 10 then convert it back at the amplifier