What's the smallest gauge wire I can use for the big 3/4 upgrade?

[Umbra]

I know the best thing to use would be 0 gauge OFC, but I got to thinking: if the alternator is rated at a certain amperage and my amps are rated at a certain wattage, wouldn't it be overkill at a certain wire size?

I have a 90A alternator and two amplifiers, one 140W RMS (35W x 4)/280W peak (70W x 4) and the other 500W RMS (@4ohms)/1800W peak (I doubt the peak rating is for 4 ohms).

If I don't plan on upgrading past these ratings, is there a cutoff to where the extra size doesn't matter, or this theory is wrong and I should just stop being cheap. Let me know.

On a related note: how much wiring to I need for an '02 Elantra?

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[momax_powers 10+ year member]

4 gauge is plenty for that

 

[Jeffdachef 5,000+ posts]

I know the best thing to use would be 0 gauge OFC, but I got to thinking: if the alternator is rated at a certain amperage and my amps are rated at a certain wattage, wouldn't it be overkill at a certain wire size?
I have a 90A alternator and two amplifiers, one 140W RMS (35W x 4)/280W peak (70W x 4) and the other 500W RMS (@4ohms)/1800W peak (I doubt the peak rating is for 4 ohms).

If I don't plan on upgrading past these ratings, is there a cutoff to where the extra size doesn't matter, or this theory is wrong and I should just stop being cheap. Let me know.

On a related note: how much wiring to I need for an '02 Elantra?

if your seriously happy with the sound and power you have right now, use a multi-meter to measure the voltage drop you have. Put heater/AC on full blast, sound system on full blast and see how low it dips. If its not going below 13.8 volts, you might not even have to upgrade anything at all. If it does dip then you can easily get away with using 4 gauge ofc.

 

[Beatin' 10+ year member]

I did a 6ga big two and it made a significant difference with my two batts and stock 90A alt.

 

[bumpasauras 10+ year member]

Are u ever planning on upgrading?? You really cannot go overkill (within reason) on power wire. For the current you are running now 4 guage is plenty but when you buy your wire 0 gauge is not that much more than 4, so why not plan ahead. If you have no plans to upgrade than 4 is plenty

 

[it'lldo]

A 4g wire can run up to 10 ft with 150 amps or 20 ft with 100 amps of current. But remember to use the same size wire for the ground. Put the ground on the same frame rail as the battery ground.

 

[Umbra]

if your seriously happy with the sound and power you have right now, use a multi-meter to measure the voltage drop you have. Put heater/AC on full blast, sound system on full blast and see how low it dips. If its not going below 13.8 volts, you might not even have to upgrade anything at all. If it does dip then you can easily get away with using 4 gauge ofc.

Is that idling or while driving?

I installed an LCD voltmeter in the dash. I was going from something like 14.6 to like 14.2 (at the lowest) with something like Decaf or dubstep with everything turned up, but that measure was while driving. I also did not have the AC on. Since summer is approaching that would be a good thing to factor in. When I was last behind the dashboard I unplugged it and it looks like I forgot to plug it back in, so I'll have to get back there and fix it for measuring while driving.

The sub amp is on ~17ft of 4ga CCA (I know, I should've sprung for the OFC). It doesn't leave me much headroom, but again, I don't think I'll be upgrading it.

A 4g wire can run up to 10 ft with 150 amps or 20 ft with 100 amps of current. But remember to use the same size wire for the ground. Put the ground on the same frame rail as the battery ground.

The one thing I'm positive I won't be upgrading is the alternator. At a certain point I need to stop and just save towards a newer car, then I can go big. If 4ga (I assume that's for OFC) can handle 150amps and I have a 90amp alt, is 4ga CCA sufficient for this project?

 

[MXcarAudio]

Is that idling or while driving?
I installed an LCD voltmeter in the dash. I was going from something like 14.6 to like 14.2 (at the lowest) with something like Decaf or dubstep with everything turned up, but that measure was while driving. I also did not have the AC on. Since summer is approaching that would be a good thing to factor in. When I was last behind the dashboard I unplugged it and it looks like I forgot to plug it back in, so I'll have to get back there and fix it for measuring while driving.

The sub amp is on ~17ft of 4ga CCA (I know, I should've sprung for the OFC). It doesn't leave me much headroom, but again, I don't think I'll be upgrading it.

The one thing I'm positive I won't be upgrading is the alternator. At a certain point I need to stop and just save towards a newer car, then I can go big. If 4ga (I assume that's for OFC) can handle 150amps and I have a 90amp alt, is 4ga CCA sufficient for this project?

try putting the volt meter right on the sub amp and look at your voltage drop when your bass hits

 

[Jeffdachef 5,000+ posts]

do what MXcarAudio just said and measure again in idle, with every power hogging thing on. If it is just dropping to 14.2 or 14, you really dont need to do the upgrade at all.