Length of battery cable matters?

[SonicRed]

Should I trim the (+) battery cable to the amp once installed or can I leave the full length cable (additional 10ft) coiled together and tucked away?

Does length of the cable matter?

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[huberoy123 10+ year member]

I usually allow a few inches extra at the amplifier, in case I have to strip the wire in the future, Then I cut off the extra and put in my workshop. The only length that matters is that you allow enough cable to connect to your amplifier.

 

[Lasherž]

Should I trim the (+) battery cable to the amp once installed or can I leave the full length cable (additional 10ft) coiled together and tucked away?

Does length of the cable matter?

As huberoy123 said, some slack is good, but you don't necessarily want it coiled up next to the amp because it can cause interference if the coil interacts with an RCA cable much worse than just a regular segment of the cable would. If you've got a very powerful preout signal, like 5v or higher, then it should be fine regardless. There's also something to be said for voltage drop, another 10ft could cause a drop of about .1-.3v depending on the quality of the cable. Trimming it won't make a huge power difference, but I think in general it's good to try and maximize your available power. Every little bit of voltage is geometrically more important for the overall power relative to the wattage of the amplifier, especially if it's not a very efficient amp like a class AB. That's why all manufacturers test their amps at a 14.4v ideal voltage, lower voltage means more amperage to make up for the difference and high amperage = heat and voltage drop.

 

[hispls 5,000+ posts]

Should I trim the (+) battery cable to the amp once installed or can I leave the full length cable (additional 10ft) coiled together and tucked away?

What amp and what cable? If ampacity of the length of cable you have is adequate might as well leave it intact, especially if you would pull the cable whenever you get rid of the vehicle. The 1/0 cable in my Jeep has already been in about 4 other vehicles and I'm still reusing pieces of 4 gauge for smaller jobs that are also about 10 years old.

 

[SonicRed]

Precisely that is why I considered keeping it the original length.

The amp is an SK-M9005D

55W x 4 RMS
300w x 1 RMS

Will length of cable be a factor?

 

[SonicRed]

Right, voltage drop is what I’m concerned about.

The wire kit is the Rockford Fosgate 8 AWG amp kit.

 

[hispls 5,000+ posts]

The wire kit is the Rockford Fosgate 8 AWG amp kit.

Probably will be plenty adequate for what you're doing even if it's say 20'. That said I wouldn't go out of my way to remove seats and trim and pull up carpet to recover 8 gauge. I mean we're talking 1.10$ a foot even for Sky High OFC or other good quality stuff.

 

[Lasherž]

Precisely that is why I considered keeping it the original length.

The amp is an SK-M9005D

55W x 4 RMS
300w x 1 RMS

Will length of cable be a factor?

Right, voltage drop is what I’m concerned about.

The wire kit is the Rockford Fosgate 8 AWG amp kit.

Voltage drop on that is going to be like .4v different than the battery. With that low of a recommended fuse rating for that amp I don't see any situation really where the difference between .4 and .25 (after cutting) will make the slightest difference in your electrical. I think your only concern here should be RCA preout voltage and interference caused by the coil of slack. If you have good wire management it's no big deal or if you have 4v preouts or above then it's whatever. If you plan on having 5 kids maybe you'll want to retain the the length for a future Yukon XL or something, but otherwise I don't see using more than 14ft in any sedan, truck, or midsized suv/van even with aggressively contoured wire routing. If you upgrade later you still won't need the full amount because you'll probably have a distribution block.

 

[n2audio 5,000+ posts]

I'm actually shocked that people aren't flipping out about this.

With all the over the top things CA nerds will try for improvements that probably can't be heard anyway -- 10' of extra power wire for no good reason seems like something that would be blowing people's minds.

You're dropping an extra .3v
Don't know why you'd want to do that if it can be easily avoided.

 

[Lasherž]

I'm actually shocked that people aren't flipping out about this.

With all the over the top things CA nerds will try for improvements that probably can't be heard anyway -- 10' of extra power wire for no good reason seems like something that would be blowing people's minds.

You're dropping an extra .3v
Don't know why you'd want to do that if it can be easily avoided.

Yeah, I mean I would cut it, but I'll never own a Tahoe. Looking again at the figures I think you're right about the voltage drop, my numbers were overly based on my 2 AWG OFC wire (which would give only .13V drop) so .3v is actually kind of a lot and presumably at 40A draw (near clipping on all channels for a class D amp @ 520W) it would go up to half a volt over just 10 feet. That's pretty substantial for not even factoring in the battery or alternator voltage drop.

I wouldn't cry over .5V but it may be worth it if you've got a battery on its last leg and your voltage stays under 13.5V from the get-go to just chop it off and consider it better.

 

[jt4x4]

What are you specifically asking? Is it safe? Yes as long as it won't get cut or damaged. Will it hurt performance? Technically yes; effectively no.

I personally would leave the full length until you are certain that's where your amp is going to stay, then cut to length. It just looks cleaner. 8g wire is cheap and easy to run.

 

[Jeffdachef 5,000+ posts]

if you are in the car audio game, length matters. you'll go crazy from not having enough length if you choose to switch things up. You wont feel a damn thing cutting the length at all soundwise. All you are doing is creating future headaches when you cut that sh*T.

 

[Slo_Ride 5,000+ posts]

If nothing else, there's no way i could deal with an extra ten feet of wire just laying around my car. Just cut the **** and make it nice and neat.

 

[Lasherž]

We're obviously a divided nation, do what you want with it

 

[jt4x4]

We're obviously a divided nation, do what you want with it

That's the most vague answer I have ever heard haha. Giving you ****, since I read the whole thread.