Thread: Few Q's about wiring

First I'm planning on doing the big three with the bat-alt wiring running from the Bat + to the fuse box post then to the alt. My question, is the fuse box post fused? I'll be putting a fuse holder between the bat and the fuse box post but do I need one from the fuse box post to the alt?
(related note) I am mounting the fuse holder on the wheel well by the fuse box but I don't want to drill holes, how else could I mount it? I was thinkin maybe velcro.

And i've read that you should ground your HU other then the factory ground to reduce noise. If I used the factory ground and ran a wire from a bolt on the HU to the chassis it would work right?

Joe

Typically...ground noise is from a difference in groundings being utilized which can produce ground loops between equipment or insufficient grounding from your hardware or other sources within the vehicle.

The easiest way to help avoid this is to use the same central ground point for all hardware. However, you must ensure that proper lengths and sizes are used(including ground bolt) or else it will produce noise as well.

Some people get out of control with these methods and you'll end up seeing 4awg ground wire running from head units to trunks. Also, big 3 is nonsense...do the math and figure out how many amps you'll actually pull and you'll realize it's not an issue with our vehicles. For those of us that don't know any better, adding up the fuse ratings of your hardware doesn't equate to actual loads.

Originally Posted by I800C0LLECT

Also, big 3 is nonsense...do the math and figure out how many amps you'll actually pull and you'll realize it's not an issue with our vehicles. For those of us that don't know any better, adding up the fuse ratings of your hardware doesn't equate to actual loads.

Actually the alt to battery is VERY useful in my car (Grand Prix) as the stock one runs around the engine about 10 miles before getting to the battery. They even sell a cable to do it.

ZZ Performance

The stock wire goes from the alternator to the starter with a 10' 8 gauge wire and then from there to the battery through another 8 gauge wire, then from the battery to the top of the under hood fuse box.

Then they list all the benefits.

Originally Posted by matt5112

If you were to look at it like this: 600 watts to the subs with an A/B amp means its drawing 1200 watts. Amp is probably fused for that. Now, you'll never get that out of the amp... but thats another story...

Exactly my point I'm only pulling about 35 amps when the knob is turned all the way. Does it spike? Probably...does it matter?...not really...does my voltage drop?...not enough to worry about...did I upgrade Big 3?...nope.

Seriously? I think you need to do some reading on how these things work. Big 3 is an internet trend that's gotten out of hand. Maybe I'm wrong but I'm doubting your stereo equipment pulls enough power to necessitate a new alternator + the cables necessary to transfer that extra power. I will admit though, 10' at 8 guage won't allow a lot of amperage through.

I don't know the size on 04+ but it looked to be 8awg running to my battery too. I'm currently running 4awg to my trunk for 2 amps that can push out a max of 500watts(a/b) and 600watts(a/b). So I'm not the most efficient and even when I crank I don't think I've ever seen it dip below 13.4V on a real hot day. Yesterday driving home in 35 degree weather it didn't dip below 14.4V

Just did the big three... New battery... lights still dim. - DIY Mobile Audio

Now start calculating your needs.
WIRE


And to help others on spending...here's one on audio cables too.
the science of cables - DIY Mobile Audio

Originally Posted by I800C0LLECT

Seriously? I think you need to do some reading on how these things work. Big 3 is an internet trend that's gotten out of hand. Maybe I'm wrong but I'm doubting your stereo equipment pulls enough power to necessitate a new alternator + the cables necessary to transfer that extra power. I will admit though, 10' at 8 guage won't allow a lot of amperage through.

I don't know the size on 04+ but it looked to be 8awg running to my battery too. I'm currently running 4awg to my trunk for 2 amps that can push out a max of 500watts(a/b) and 600watts(a/b). So I'm not the most efficient and even when I crank I don't think I've ever seen it dip below 13.4V on a real hot day. Yesterday driving home in 35 degree weather it didn't dip below 14.4V

Just did the big three... New battery... lights still dim. - DIY Mobile Audio

Now start calculating your needs.
WIRE


And to help others on spending...here's one on audio cables too.
the science of cables - DIY Mobile Audio

Not trying to argue with you here just trying to figure it out. My setup is 4ga wire to a 600rms class D amp, 8ga back to a 220 watt amp(I am assuming this puts out less then 100rms). Gains have been set with a DMM the right way. Listening to music lets say a little above normal I get headlight/dash light dimming.

Now yes I understand my system should not be pulling near enough to make my lights dim, so my question to you why do YOU think I am getting dimming and how would YOU fix it?
(btw Yellow Top battery also)

Thanks,
Joe

Interesting dilmena...lights still dim?

I'm not going to talk trash about any of your equipment but I've seen kids with the same problem switch out an amp and the problem is resolved. The reason a high quality amp may not suffer these issues is that they have all the capacitance needed built into them already. It's all about designing balanced hardware. Some lower end(even name brand) amp lines try to skimp on build parts. Manufacturer's generally use one amp design across as many markets as possible.

A quick fix in these situations can actually be the use of a capacitor. The problem isn't that you don't have enough available power it's just that batteries are not designed for a high draw of current in short time spans but capacitors are.

But a battery was designed for loads over a long period, not spikes in power draw. Therefore, it will cause voltage to drop and lights will dim instead of flicker. The issue isn't lack of power, just the ability to transfer it quickly enough. A well built amp has enough caps to keep a consistant load on the electrical. A poorly made amp will not be as consistent with its load which can lead to dimming lights from these spikes. However, you also have to consider how much power a speaker might draw. Longer waves need more power for a number of reasons and that's why the dimming seems to coincide with the bass notes.

Originally Posted by matt5112

Longer waves don't need more power. Higher sound levels need more power. The highest level content in music and all media is typically the bass which is why those need the most power.

The battery only provides power when the system voltage reaches the output voltage of the battery (13V and under, typically 12.5). The part about the caps is true to an extent, caps only store enough energy for very brief periods of time (0.03 seconds).

Key words...."number of reasons"

Tweeters will never be able to handle the power a subwoofer can. My home theatre sub only utilizes about 35watts @ 8ohms. Majority of mainstream subs are designed to handle a lot of power and are very inefficient. There's a number of reasons subs need more power these days...listening preference, design, marketing, spl, etc.

Bottom line is that those sub notes cause a spike in power needs. A poorly designed power supply in an amp will not pull consistantly on the alternator and battery. If his voltage is dropping we don't know why just yet. If he has a 125amp alternator I would be shocked if that's the issue. His amps are rated a little less than mine and all I have is decent entry level equipment. My guess is that the 8awg from the alt. can't deliver on those power spikes and the battery can't keep up either. In these instances a cap can be a band aid. You can try the big 3 as well but like Matt said...this is a science.

Think it through so you don't waste time and effort on nonsense and think LONG TERM DESIGN too.

Originally Posted by I800C0LLECT

Bottom line is that those sub notes cause a spike in power needs. A poorly designed power supply in an amp will not pull consistantly on the alternator and battery. If his voltage is dropping we don't know why just yet. If he has a 125amp alternator I would be shocked if that's the issue. His amps are rated a little less than mine and all I have is decent entry level equipment. My guess is that the 8awg from the alt. can't deliver on those power spikes and the battery can't keep up either. In these instances a cap can be a band aid. You can try the big 3 as well but like Matt said...this is a science.

Think it through so you don't waste time and effort on nonsense and think LONG TERM DESIGN too.

I'll try the alt to fuse box wire since I have the stuff for it, fast and free to check. If that don't help it is between a cap or a better amp, I don't feel comfortable enough to have a cap in my car so it will be a better amp.

Thanks for your help

Any other options other then a cap? So far I have read the Big 3 is a great thing, then I read it was not necessary. I start off assuming a cap could be useful then I read it is useless and just a bandaid fix for a bigger problem.

There is WAY TO MUCH contradiction going on with car audio, I guess it is a try it and see if it works for you kind a thing.

Originally Posted by matt5112

Its a science. People try things, and if it works in one case, people assume it works in all. Sadly, science doesnt work like that.

I can't get the volt drop right now as I took my carpet out due to the "water on the floorboard" problem. I reran all my wires while i had it up and haven't got it all put back together yet.

When I get it all setup ill measure the volt drop. Then I'll put a 4ga cable from my alt to my fuse box and do it again to the same song with the same volume just for the hell of it, can't hurt nothing, if it don't do anything I'll take it off, it helps even a little I'll keep it on.

Few more question for you two.
(1) My small amp is cheap (maybe $30, I'll be replacing this when I get the money) would it be enough to cause my dimming seeing how small it is? (I had just my sub amp hooked up for a while before and it never dimmed.)

(2) What is the average draw from an amp on the remote wire? or do you think a relay is necessary on a remote wire? (I'll check mine when I get it all setup)

Originally Posted by Joe

I can't get the volt drop right now as I took my carpet out due to the "water on the floorboard" problem. I reran all my wires while i had it up and haven't got it all put back together yet.

When I get it all setup ill measure the volt drop. Then I'll put a 4ga cable from my alt to my fuse box and do it again to the same song with the same volume just for the hell of it, can't hurt nothing, if it don't do anything I'll take it off, it helps even a little I'll keep it on.

Few more question for you two.
(1) My small amp is cheap (maybe $30, I'll be replacing this when I get the money) would it be enough to cause my dimming seeing how small it is? (I had just my sub amp hooked up for a while before and it never dimmed.)

(2) What is the average draw from an amp on the remote wire? or do you think a relay is necessary on a remote wire? (I'll check mine when I get it all setup)

1) Your bass notes go as high as 300hz which are handled by your mids. A bad amp design can be a heavy tax on the electrical system in your vehicle. I think you found the culprit. However, that doesn't mean go out and buy a new amp. It just means you need to design your power system around that.

2) I wouldn't worry about the remote turn on. Typically installers will tell you it's ok to turn on 2 amps. Personally, I have wired up a relay for my equipment. There's something you should add in case of backfeed to your head unit tho...forgot what it is. I didn't throw it in mine; it's for additional protection.