ok, a mechanics perspective on the BIG3

playa1
10+ year member

CarAudio.com Elite
ok, i told my dad ( he's a Mechanic) that i wanted to upgrade my big 3 and he says that it really doesnt need to be done. His perspective is that if the alternator is made to do say 105 amps, then the factory gave that Alternator big enough wire to to adequateley supply that 105 amps. So he say to eliminate the process of the big 3 just wire the amps ground straight to the battery, even though he doesnt think the upgrade is necessary. Is he right, he is usually right about everything else. If not can you explain for me and him. I am going to do the upgrade anyways but i just wanted to know about this.

Mike

 
also, since i get the same prob from my mechanics...shouldnt you upgrade the wire since the factory didnt really expect a music system in the vehicle which would be ******* so much current...?

 
Running a ground from the back of the car from the battery is not required. You do need to upgrade the battery to chasis ground if you are using 4 gauge or larger for your stereo.

Reason being, Ford, GM, etc did not anticipate you adding another 80A load to the car's charging system. Factory grounds are often 8 gauge at best. So when you run 4 gauge power to your amp, you have basically just an 8 gauge ground at the battery. Why run all that 4 gauge to cut yourself short....I would say at least upgrade chasis to battery.

 
you can get around the battery ground to frame part by running wire straight from your battery + and - to your amps, and also get around noise problems. you still need to upgrade your + to alternator wire and your alternator's ground though.

 
then the factory gave that Alternator big enough wire to to adequateley supply that 105 amps.
I'm sorry, but I highly doubt the factory anticipated large, current-drawing loads to be placed on the charging system, nor would they have spent the extra $$$ (read: lower profits) to make sure the system was up to the task of doing anything but running what came with the vehicle stock. For example - both my van and my dad's '91 F-150 came stock with a 10awg ground from the battery to the frame. You're telling me that's suitable for 135 amps? //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Ford built the electrical system to handle what they put in it...nothing more.

And if you ever do upgrade your alternator, your reasoning is no longer valid //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 
Before I knew about the big 3 I had my plow truck that was electric over hydraulic. Well when I would raise the plow lights would almost shut off and system went really low. MY mechanic said dont upgrade the alt. I had 2 bats running he ran some 2 gauge ground wire from both my bats to my chas and that almost stopped the problem. Since then I knew what people were talking about with the big 3 and how much it can make a diffrence now.

 
The factory never builds cars to their full potential in any regard.

Add a cold-air intake.

Add a turbo kit.

Add a DVD player.

Add a big subwoofer.

Add leather seats.

.. My priorities are fUct up //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 
Ok , he says for example my system, it has a 150A fuse on the power wire and 3 30A fuses on the amplifier, He wants to know how many amps on average would the amplifier be pulling on normal listening levels. That even though there is 120 A in fuses that it wont be pulling 120A all the time unless it was using the amplifiers full potential and on the lowest of bass notes.

* That's why a mechanic gets paid to work on mechanical things.
Read: moving parts.
And my dad isnt JUST a mecahnic, he is a man of all trades, electrician being one of them. He is also the guy that does most of the electrical work at his shop, he isnt just some run of the mill dude, he does know whats going on.
please respond //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 
the key idea is, if you are going to upgrade the stereo, you should upgrade the electrical system. also "good enough" doesn't mean that there is no room room for improvement. i bet the stock wires to your factory speakers aren't the best. is the stock battery as good as a die hard gold? they are called upgrades not necessities. if dimming lights and dead batteries are something you like, don't worry about it. but if you want to upgrade your system, then go for the big 3.

 
Ok , he says for example my system, it has a 150A fuse on the power wire and 3 30A fuses on the amplifier, He wants to know how many amps on average would the amplifier be pulling on normal listening levels. That even though there is 120 A in fuses that it wont be pulling 120A all the time unless it was using the amplifiers full potential and on the lowest of bass notes.
That is true.

But as an electrician he should know Ohm's Law like the back of his hand, and realize how to correctly size wire to prevent voltage drops. Even if the wire isn't in danger of thermally self-destructing, he should know what an undersized wire will do to voltage drop at the load. It's like wiring a 'fridge off of 18awg Romex.

 
The 120a is to break a short, should one occur; A direct short on your car's battery isn't pretty, especially if you're driving.

And that wasn't meant to be a shot at your Dad's skills //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 
the key idea is, if you are going to upgrade the stereo, you should upgrade the electrical system. also "good enough" doesn't mean that there is no room room for improvement. i bet the stock wires to your factory speakers aren't the best. is the stock battery as good as a die hard gold? they are called upgrades not necessities. if dimming lights and dead batteries are something you like, don't worry about it. but if you want to upgrade your system, then go for the big 3.
I am looking for informative answers to help educate me and my father not just do it because you upgraded something else and get it over with. Thanks anyways.....

 
The 120a is to break a short, should one occur; A direct short on your car's battery isn't pretty, especially if you're driving.
And that wasn't meant to be a shot at your Dad's skills //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
Thats cool i wasnt just directing it towards you, just getting rid of the doubts in everyones heads if they though that he was just a mechanic and didnt know what he is talking about.

 
Is the sytem installed? Have him put an amp meter on the positive wire (electrician, mechanic, technician should have that tool ), you'll see exactly how many amps it pulls first hand.......It will vary just based on impedance of the load, volume and gain. Use normal music, then a test tone, you'll see a very large difference......

 
Ok another response from father. he says that cars coming from factory are grounded enough to prevent spikes in the electrical system and chances are that the alternator and battery are grounded more than a couple of times and they are even grounded from the exhaust to the frame just to insure that there are no drops. And he is not saying that the big 3 does not work, he is saying to prevent doing the big three just wire the ground from the amp to the battery.

And he said there is no 18 awg romex //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 
And what is the problem with it to begin with all you are doing is upgrading the wire. It is not going to hurt anything. My amp in my car i didnt do the big 3 yet and had a small fuse a 50amp. On a kicker sx 1250.1 ran great most of the time but when i really went to turn it up i would blow a fuse so that just shows you how much draw was going on daily for me.

 
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