# Question about upgrading the power cable



## 98sr20ve (Oct 6, 2002)

The oem power line is small and it would seem that running a good gauge wire straight from the battery would be better. Two questions.

1) Is it the switched or the non switched wire that actually powers the amps in a headunit.

2) If it is the switched then I would need to use a relay in that line and use the oem switched line to trigger the relay. At least thats how it seems. 

3) I am installing a Clarion Headunit with 50wattsX4 (really more like 17X4 RMS). Is this even worth the trouble.

I don't mind the work really. Any ideas? This is on a 92 240SX


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## chimmike (Oct 17, 2002)

a non switched wire powers the head unit as far as I know.......get a wiring harness for that particular car and you should be able to solder/connect the wires from the hu to the connector and plug right in to the stock harness..........and you'll be good to go.


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## sr20dem0n (Mar 19, 2003)

98sr20ve said:


> The oem power line is small and it would seem that running a good gauge wire straight from the battery would be better. Two questions.
> 
> 1) Is it the switched or the non switched wire that actually powers the amps in a headunit.
> 
> ...



No need for a special power wire, you'd be lucky if you're even pulling 50 watts out of that internal amp. Definately not enough for a designated power wire straight to the battery.


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## chimmike (Oct 17, 2002)

hey Steve, I emailed that troll that bothered you about the tranny and told him he's worthless...he e-mails me back an obscenity-filled email saying he talked to you in person and you lied, LOL blah blah, I just deleted it. what a cock, haha


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## wickedsr20 (Aug 8, 2002)

98sr20ve said:


> The oem power line is small and it would seem that running a good gauge wire straight from the battery would be better. Two questions.
> 
> 1) Is it the switched or the non switched wire that actually powers the amps in a headunit.
> 
> ...


You should be just fine using the OEM wires to power your head unit. Even at full tilt, your radio will not draw enough current to create a problem requiring a wiring upgrade. Only if you're anal retentive would this even be given a second thought. Not to mention that you will not push the internal amp of your head unit too hard anyway because distortion will set in and you'll be backing off the volume a bit to keep it clear sounding. If you find you need more sound for your highs later, you'll be adding the appropriate amp with the appropriate wiring in the future, relieving 80% of the load from your radio and making the larger wiring completely unnecessary.

1) BTW, the switched wire actually powers most radios, while the non-switched wire is mainly there to provide power for the clock and to retain all memory settings in the radio. 

2) If you did upgrade the wiring, you would not need a relay in line, but you would need an in-line fuse. The main times a relay is used is to create a larger current flow from a smaller current flow, such as powering multiple amps and sound processors from the remote lead of the radio or using a low current trigger to trigger higher current devices like fog/auxiliary lights.

3) Yes because you would get better quality sound and in most cases more usable volume from an aftermarket radio. It would also be worth it to me because if you add an amp in the future, you'll get a much cleaner overall signal from the Clarion vs. the OEM unit.


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## 98sr20ve (Oct 6, 2002)

Wicked, thanks for your reply. Ok, here is the full deal. The 240 is going to be primarily a track car so adding another amp is really not what I want to do. I have been researching lighting (headlamps) and the research shows that a current drop 10% gives a even greater drop in headlight output. I know that lights draw much more then a amp but people do upgrade the power on external amps so I figured why not on the headunit. Cost is small (already have most the stuff) and it may help. I deleted the front speakers (4X6) in the intrest of cost and weight. My sentra fronts are uesless so I figured why pay to put them in the 240.



wickedsr20 said:


> 1) BTW, the switched wire actually powers most radios, while the non-switched wire is mainly there to provide power for the clock and to retain all memory settings in the radio.


OK, thanks.



wickedsr20 said:


> 2) If you did upgrade the wiring, you would not need a relay in line, but you would need an in-line fuse. The main times a relay is used is to create a larger current flow from a smaller current flow, such as powering multiple amps and sound processors from the remote lead of the radio or using a low current trigger to trigger higher current devices like fog/auxiliary lights.


But if the switched wire runs the amp then I wouldn't I need a relay in that line? Otherwise if I run it straight from the battery it would be non-switched and the radio would be on all the time.



wickedsr20 said:


> 3) Yes because you would get better quality sound and in most cases more usable volume from an aftermarket radio. It would also be worth it to me because if you add an amp in the future, you'll get a much cleaner overall signal from the Clarion vs. the OEM unit.


Already bought the headunit. I was meaning would the upgraded power supply line be worth the trouble. For some reason I am inclined to think it would but maybe I am wrong.


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## sr20dem0n (Mar 19, 2003)

it will not be worth it, you will notice no difference
I thought I explained this before but apparently not...

You'd be lucky if that headunit put out 50rms
assuming 60% efficiency, you'd be sucking ~6amps at the very most. During normal listening you're looking at closer to 3 amps. 6 amps is nowhere NEAR enough to require a wiring upgrade, you probably have less than 10ft of 18ga as it is, with a 6amp draw and 10ft of 18ga you'll get a .4V drop between your battery and your headunit. This is NOTHING when you're dealing with the miniscule power headunits put out, you MIGHT lose a quarter of a watt by it. Hell just turning on your headlights or air conditioning will make more of a difference than this will. Also, upgrading your power wire for the headunit will do absolutely nothing for the rest of the electrical system, all it will do is reduce the voltage drop at the headunit itself. It has 0 effect on your lights, alternator, battery, etc.

The reason you use a separate power cable for external amps is because external amps can suck over 50 times more current than that headunit will, and they will melt 18ga wire if you try to use it.


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## wickedsr20 (Aug 8, 2002)

98sr20ve said:


> But if the switched wire runs the amp then I wouldn't I need a relay in that line? Otherwise if I run it straight from the battery it would be non-switched and the radio would be on all the time..


That would be the case if they were two independent power sources. However with radios, the switched circuit (ignition on/off - usually red) will act similar to what you are trying to do, and cut off all power when the key is switched off or the radio is turned off. A relay would not be necessary for what you have in mind.



98sr20ve said:


> Already bought the headunit. I was meaning would the upgraded power supply line be worth the trouble. For some reason I am inclined to think it would but maybe I am wrong.


In reality, it couldn't hurt, but I don't think you'll draw enough current or have a large enough voltage drop across the smaller gauge wiring to be noticeable.


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