big 3 doesnt do nothing?

[hellomota]

i have 16 awg for my big 3 and it helped my dimming problem.

joke.

 

[toaster 10+ year member]

current is the major part of the power equation, as related to voltage drop.

as for the battery when the engine is running? the battery is just another load to the alt, same as amps, caps, lights, etc...

 

[DiamondFanatic 10+ year member]

Batterys do buffer against voltage drop though. I would do upgrades 1.big 3 2.batt 3. alternator, but thats just me.

 

[toaster 10+ year member]

yes, there is some capacitance value there. thats not really the point i was trying to make tho, as related to the charging lead....

 

[QualityCarErock 10+ year member]

Your dad has a good head on his shoulders. He isn't wrong about their really not being a big difference unless you're dealing with a good length of cable. The part he's not considering though is what the max amps that can be ran through smaller cable is. There is a cutoff as to how much current each size of cable can deliver. 4 gauge is roughly 130 amps. 0 gauge is 220 i think. So, if it's 8 gauge and your system requires 100 amps and 8 gauge cannot transfer any more then say 60 amps, then yes, you have a need and a benefit for upgrading.

 

[imaspaceguy90 10+ year member]

I prolly owuldnt touch your car with a 60amp alt man, most cars take around 40 for just running the car, leaving u 20 amps for anyhting u want, a big 3 would prolly be a waste unless your car had above 80 amps, my car is a 110 amp alt, and i only ran 4 guage wire because i did the calculations and that would be the perfect wire to use with the amp draw i have. Convert you Amps to wire guage.

 

[helotaxi 5,000+ posts]

Also, the current consumption will not increase when the voltage drops. I=V/R, the resistance of the load stays the same, as the voltage drops, the current will also decrease.

Current consumption does increase as voltage drop. You are considering the wrong part of the system when you are applying equations. The amplifier tries to keep its power output constant, regardless of the voltage it is getting from the car. For it to maintain a constant power with a dropping voltage, current must increase. The real problem that is caused by this is that as current increases, the voltage drop from the resistance of the power delivery path increases which increases current requirements further and on and on and on. If the power supply transisitors and diodes could handle unlimited current, voltage wouldn't matter as long as you could get enough current, but since these devices can only flow a finite amount of current before they exceed their power dissapation rating, most amps are equiped with undervoltage protection circuits that shut the amp off before this can occur.

And lastly, power is what causes heat, P=V*I.

True, but probably not in the sense that you are thinking. Power is lost as heat. As current flows through a resistance there is a reduction in voltage across that resistance expressed as V=I*R. When you are figuring power lost as heat, the voltage drop is the voltage that is used for the calculation. So if for instance, you are getting a 1V drop over a run of cable at 100A you are losing 100W over that run of cable. Cable is not very good at shedding heat and that heat will build up and start to cause problems. Firstly resistance increases with heat. More resistance equals more loss and more heat build up. Basically, having an insufficient power delivery setup is a self feeding downward spiral. Not only will it cause poor performance from your audio setup and serious dimming problems which are annoying, but if it is severely deficient, it can cause damage to components and/or the car.

A few more points of clarification. The alternator is designed to be the primary source of power for all things electrical in your car while the engine is running. They are speced to the stock electrical needs of the car as it was delivered. This headroom wasn't meant to allow you to add a stereo. It was meant to allow the alternator to operate well within its capacity while supplying power for all the accessories built into the car and still be able to recharge the battery from the discharge required to start the car. That is the design goal behind it all.

When you add a high power stereo to the equation and don't do anything to upgrade the electrical system (even something as simple as upgrading the big 3 to minimize wasted power) you have upset the apple cart. At low-med volume and with a light accessory load, there is not a problem. The lack of an accessory load gives the stereo some power to work with without taxing the alt. At this point the battery is just another load (though a very small one) on the alt and the alt is suppying all the power needed by the car and stereo. Now switch over to a hot summer night. You've got the AC up the headlights on and the stereo going. This is the highest accessory load that the alt was speced for and now you have added the stereo draw on top of that. The result is now that when the bass hits and the stereo is drawing maximum power, the alt can't supply that power at the normal voltage. As a result the voltage drops (constant power) with the increase in current demand. Once the voltage drops to the the discharge voltage of the battery, the battery begins to contribute its stored power to the equation and staves off a further instantaneous voltage drop. The battery can easily supply several hundred amps of current for a short period so this is good. The problem is that as soon as the demand goes back down, the battery is again a load on the alt and since it is now partially discharged, it is a larger load than before and stays a larger load until it is fully recharged. If this was a single musical transient, then, no problem, but if the situation keeps repeating itself without enough of a lull in demand for the battery to recharge between each spike in demand, you will eventually get to the point where the alt cannot supply power for the car, the stereo and the recharging of the battery all at once. At this point the battery is in a state of perpetual discharge until the load is reduced to a point that the alt can again fully handle.

Getting to this state can have several negative consequences:

1) During this entire time, the alt is working at its maximum capacity. It isn't designed to do this. It will get very hot and it will shorten the life of the alternator.

2) If the battery isn't a deep cycle, discharging it in this way will shorten it's life greatly.

3) Continually running your amps on a lower voltage, while it may not hurt them directly, isn't helping their life either. They're going to run hotter and stay hotter.

In this vein, the big 3 can help with dimming problems. By reducing the voltage losses between the alt and the battery (the basic distribution hub for the car's electrical system) operating voltage will remain more constant during high curent demand sutuations. Also since less power is pissed away as heat, more is available for other uses.

 

[Megalomaniac 5,000+ posts]

I know this is a good thread but isnt this consider post dumping? this thread was made in october of 05'

 

[PV Audio 5,000+ posts]

No, it's called bumping old as shit threads.

 

[prochobo 10+ year member]

haha wow this is old. Anyways for me:

10.8v lowest, no big 3

11.6v lowest, big 3 done.

 

[johnecon2001 5,000+ posts]

Hi,
Well, me and my dad got into an argument, since i was saying that speaker gauge wire does matter in a way. He said it doesnt and that i should stick to 16 awg wire for the doors, which most ppl would recommend, but i already got the 12 awg and i really dont feel like spending anymore. Anyways, i told him awg does matter, such as in the Big 3 and he said that the stock wiring is fine (imma assume its 8 awg) from the alternator to the battery and that it would be a waste of money and time to switch the cable to any higher gauge. Ive read many articles saying it did help ALOT, but i really need to prove him wrong, with facts or im about to get proven wrong. To start....

- does awg matter? Such as a 1/0 or hell even 4 awg for a big 3 with high power amps and car?

- does a big 3 even do anything?

- he said that awg only matters in long distances, true or false?

- Facts please.

My dad also said get a capicitator instead of a new battery or alternator......

He also said that all ya just want to make money (um ya r making money by helpin/sayin stuff on the forum?) and that none of you probably have a degree in electronics or some shit.

Really this thread is to either prove him right or wrong but since im already making a new thread.....

which one should i replace as a top priorty due to dimming, the alternator (60 amps) or the battery? How many amps alternator should i get for a 1000 watt class d system, plus a 600 watt class a/b system? I also plan on adding a supercharger or turbocharger, if it matters. Would it matter if i got a high amperage alternator, say 200 amps or is that too much and could cause problems?

Thanks

You dad is a typical old schooler. Back in the day when systems weren't high powered and no one had done any tests on this stuff.. he would have been correct.

Now though, test and other smart people PWN him.

Let me start out by saying for wire in the doors, 16awg is fine. If you only bought 12awg, just use that.

He would also be correct about the stock wiring in cars. But what he fails to realize is that in the applications we're talking about, your systems are drawing easily 80-200A over what the stock system was ment to handle therefore making his statement incorrect.

Use the example of plumbing. The smaller the pipe the more pressure is increased and the less water flows. If you have a larger pipe the water will flow more easy.

Long distances and short alike, if you have to move a lot of whatever, you need that larger awg to prevent restriction of flow.

A capacitor is just something else for the alternator to charge. Which, if it's already failing to keep up with your system, how is it supposed to charge the cap too?

You should definitely get a new alt. For the amount of wattage you are running do a little math. 1600w / 14.4v = 111.11a (assuming 100% efficiency). If your stock alt is already max'd out. You need to look for something in the 160-180A range. Maybe even go to a 200a to give yourself head room.

A larger alternator will NOT cause any problems. Read the sticky reguarding this in the electrical forum.

All in all you're dad isn't wrong, he just doesn't have the right info to back up his assumptions.

EDIT: dang it I should have //content.invisioncic.com/y282845/emoticons/read.gif.ff512c499c00ed3faae9a20f4b088b29.gif