Question on my electrical

[kirill007]

Regarding voltage drop: You are forgetting to account for the fact that car audio wire is oversized. With 0 gauge being closer to 2/0, and sky high's 2/0 being closer to 4/0. That is also voltage drop purely across the front-back wire, and doesn't take into account things like connections, wiring post-distribution block/battery, grounds going out of the amp, or the voltage drop across the frame. Your real world voltage drop will be a lot more.

If I plug in a 15ft length of wire(front-back + ground length + rear batt-to-amp length), 300a load, and a wire temperature of 60C: I get the following

2/0 Alumnum: 1.36v

2/0 OFC: 0.83v

4/0 OFC: 0.52v

That's roughly a .2v difference between the 2/0 and the 4/0. Pretty significant IMO. Dropping to 12.6 vs. 12.4.. 12 flat vs 11.8. Etc. And those rockford amps really don't like low voltage. With OP's electrical he'll need every bit of help he can get..

Regarding fuses:

The fuses we use in car audio are referred to as "slow blow" fuses. You can run more than rated through a fuse and it will take some time to blow. Can't find the thread, but a member on here ran a stupid amount of power through a 300a fuse during a comp and it didn't blow. The fuse was all discolored from heat, but yet it didn't blow.

Quick review on ohm's law

I=V/R

Current = voltage/resistance.

V=RI

Voltage = Resistance * Current

Stock batteries aren't really known for being low resistance. That's why we upgrade them. High internal resistance in the battery = heavy voltage drop under load. Holds true with V=RI

Now if we take a look at our current equation, I=V/R. If you lower the voltage (battery voltage drop under load) and your source of resistance is the short, wire, connections, fuse, return path, etc. It could take an extended amount of time for the fuse to blow. If at all. Hence why I said to err on the smaller side of a fuse rating.

Also consider that with OP's electrical. Stock alt, stock battery. I doubt he'll be able to pull 300a through his front-back run. I see something more like pulling ~200a from the front batt+alt, ~100a from the rear battery

Red: You'll be surprised at how little it is oversized if you actually measure the crosssectional area of the copper itself. (that means the each strand seperately.)

Blue: You'll see if you are comparing wire sizes with all those connections included that the difference that the wire makes will be even smaller.(and the price will go up exponentially for no benefit at all in his application)

I understand that you like overkill like most people here, because they don't know how to properly calculate it, but I've done this quite a few times. (and most of it wasn't in car audio btw )

A wire temperature of 60 degrees? That's a little on the high side isn't it? That's too hot to touch. The temperature won't be that high with only a 300A continious load. ( Do you really think there will ever be a 300a continous load with those amps?)

Green: Seems you really like overkill, a difference of 0.2V is nothing. (most likely you won't even get a 0.2V difference because of the lower load and lower wire temperature)

OP shouldn't even try to run those amps with his electrical 0 guage or 1000MCM wiring it doesn't matter.

(Offcourse you can run multiple amounts of the rated current through the fuse without blowing it as long as the time is short.)

[Skax]

Regarding voltage drop: You are forgetting to account for the fact that car audio wire is oversized. With 0 gauge being closer to 2/0, and sky high's 2/0 being closer to 4/0. That is also voltage drop purely across the front-back wire, and doesn't take into account things like connections, wiring post-distribution block/battery, grounds going out of the amp, or the voltage drop across the frame. Your real world voltage drop will be a lot more.

If I plug in a 15ft length of wire(front-back + ground length + rear batt-to-amp length), 300a load, and a wire temperature of 60C: I get the following

2/0 Alumnum: 1.36v

2/0 OFC: 0.83v

4/0 OFC: 0.52v

That's roughly a .2v difference between the 2/0 and the 4/0. Pretty significant IMO. Dropping to 12.6 vs. 12.4.. 12 flat vs 11.8. Etc. And those rockford amps really don't like low voltage. With OP's electrical he'll need every bit of help he can get..

Regarding fuses:

The fuses we use in car audio are referred to as "slow blow" fuses. You can run more than rated through a fuse and it will take some time to blow. Can't find the thread, but a member on here ran a stupid amount of power through a 300a fuse during a comp and it didn't blow. The fuse was all discolored from heat, but yet it didn't blow.

Quick review on ohm's law

I=V/R

Current = voltage/resistance.

V=RI

Voltage = Resistance * Current

Stock batteries aren't really known for being low resistance. That's why we upgrade them. High internal resistance in the battery = heavy voltage drop under load. Holds true with V=RI

Now if we take a look at our current equation, I=V/R. If you lower the voltage (battery voltage drop under load) and your source of resistance is the short, wire, connections, fuse, return path, etc. It could take an extended amount of time for the fuse to blow. If at all. Hence why I said to err on the smaller side of a fuse rating.

Also consider that with OP's electrical. Stock alt, stock battery. I doubt he'll be able to pull 300a through his front-back run. I see something more like pulling ~200a from the front batt+alt, ~100a from the rear battery

Red: You'll be surprised at how little it is oversized if you actually measure the crosssectional area of the copper itself. (that means the each strand seperately.)

Blue: You'll see if you are comparing wire sizes with all those connections included that the difference that the wire makes will be even smaller.(and the price will go up exponentially for no benefit at all in his application)

I understand that you like overkill like most people here, because they don't know how to properly calculate it, but I've done this quite a few times. (and most of it wasn't in car audio btw )

A wire temperature of 60 degrees? That's a little on the high side isn't it? That's too hot to touch. The temperature won't be that high with only a 300A continious load. ( Do you really think there will ever be a 300a continous load with those amps?)

Green: Seems you really like overkill, a difference of 0.2V is nothing. (most likely you won't even get a 0.2V difference because of the lower load and lower wire temperature)

OP shouldn't even try to run those amps with his electrical 0 guage or 1000MCM wiring it doesn't matter.

(Offcourse you can run multiple amounts of the rated current through the fuse without blowing it as long as the time is short.)

yea that's what I want to do for know just be able to play it for short periods of time until I get my d3100 , with that being said what wire should I run from front to back battery and fuse size and what wire and fuse after battery

[Skax]

Sorry double post

[kirill007]

You can either listen to me and not overpay for what you need at the moment or pay up to twice as much and go with the suggestions snowdrifter made, this will leave you with room to upgrade in the future.(Even though the upgrade won't be able to be very big)

My suggestion: Good 0 guage copper (OFC) wiring with 2 300 amp fuses at both ends of the cable.

A distribution block from one 0 guage input to one 0 guage and 4 guage output. (a 300amp fuse for the 0 guage from distribution block to RF amp and a 150amp fuse from distribution block to the other amp)

OR

Snowdrifter's suggestion:

2/0 guage copper (OFC) wiring with 2 400A fuses and then distribution block from 2/0 guage to one 0 guage and one 4 guage output.

Fusing after distribution block is the same as mine.

+Pro's of my suggestion:

Cheaper wire and connections (easier to find too)

Works good

-Con's

No upgrade possible without adding another run of wire. (which is easier in most vehicle's then routing a 2/0 guage wire)

+Pro's of his suggestion:

Less voltage drop (very little difference)

You can upgrade later (but the upgrade can't be too much because the 2/0 guage is only rated to 400A and 1/0 guage to 300A)

-Con's

Harder to route the wire through the car.(in some/most cases)

More expensive and more difficult to find connections.

BUT what I and everyone probably agrees on is that you need to upgrade the electrical (i.e. alternator and add 1 extra battery in the back)

3000W on stock electrical won't work unless you won't play it at full capacity.

[SnowDrifter]

Red: You'll be surprised at how little it is oversized if you actually measure the crosssectional area of the copper itself. (that means the each strand seperately.)

Blue: You'll see if you are comparing wire sizes with all those connections included that the difference that the wire makes will be even smaller.(and the price will go up exponentially for no benefit at all in his application)

I understand that you like overkill like most people here, because they don't know how to properly calculate it, but I've done this quite a few times. (and most of it wasn't in car audio btw )

A wire temperature of 60 degrees? That's a little on the high side isn't it? That's too hot to touch. The temperature won't be that high with only a 300A continious load. ( Do you really think there will ever be a 300a continous load with those amps?)

Green: Seems you really like overkill, a difference of 0.2V is nothing. (most likely you won't even get a 0.2V difference because of the lower load and lower wire temperature)

OP shouldn't even try to run those amps with his electrical 0 guage or 1000MCM wiring it doesn't matter.

(Offcourse you can run multiple amounts of the rated current through the fuse without blowing it as long as the time is short.)

Red: The calculator I used assumes stranded conductors

Blue: Yeah, the calculator doesn't take into account the resistance of connections. And regarding wire temperature: That's 140 degrees Fahrenheit. Not an unreasonable temperature during a summer day, and the wire is sitting on the floor of the car, which is being heated by hot asphalt. You engine bay can get even hotter than that still. Think of it more as an average wire temperature in a worst case scenario.

Green: Yes. I do like overkill. Also because I've seen the difference that wiring makes. It's really interesting seeing someones alternator voltage be at 15.x and their rear battery voltage being only in the mid 13s. Agree that OP needs more electrical to run this amp

[Skax]

You can either listen to me and not overpay for what you need at the moment or pay up to twice as much and go with the suggestions snowdrifter made, this will leave you with room to upgrade in the future.(Even though the upgrade won't be able to be very big)

My suggestion: Good 0 guage copper (OFC) wiring with 2 300 amp fuses at both ends of the cable.

A distribution block from one 0 guage input to one 0 guage and 4 guage output. (a 300amp fuse for the 0 guage from distribution block to RF amp and a 150amp fuse from distribution block to the other amp)

OR

Snowdrifter's suggestion:

2/0 guage copper (OFC) wiring with 2 400A fuses and then distribution block from 2/0 guage to one 0 guage and one 4 guage output.

Fusing after distribution block is the same as mine.

+Pro's of my suggestion:

Cheaper wire and connections (easier to find too)

Works good

-Con's

No upgrade possible without adding another run of wire. (which is easier in most vehicle's then routing a 2/0 guage wire)

+Pro's of his suggestion:

Less voltage drop (very little difference)

You can upgrade later (but the upgrade can't be too much because the 2/0 guage is only rated to 400A and 1/0 guage to 300A)

-Con's

Harder to route the wire through the car.(in some/most cases)

More expensive and more difficult to find connections.

BUT what I and everyone probably agrees on is that you need to upgrade the electrical (i.e. alternator and add 1 extra battery in the back)

3000W on stock electrical won't work unless you won't play it at full capacity.

the other amp is a 50 amp fuse though would fusing it with 150 be appropriate?? I thought 250 for fosgate amp and 50 for other amp?

[SnowDrifter]

Is this, by any chance, your first build?

[coh33dkill3r]

This sounds like his first "major" build.... Best thing for you to do man is read read read and then read some more.... Do your homework. I just built a box for my sub and spent the last month reading thread after thread to make sure I had everything right before I even got the wood for it.. There's ALOT Of info being said on this site and you can learn everything you need to know here

[BigManAC]

I'd you don't have a volt meter, get one. Those amps draw tons of power and you'll need to watch it.

What alt do you plan on getting?

i got a stinger volt meter and also not sure on alt can't find one for a 2000 Saturn l series :/

If you go to singer her will have one for you bc I have a L200 and he had a 275amp for me

[BigManAC]

Also if you are gonna upgrade the front bat to a AGM the. You need to take out the rear or upgrade it as well. Mixing AGM bat and regular automotive bat is no bueno.