what is the big 4
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=100159
Printed Date: June 15, 2024 at 3:49 PM
Topic: what is the big 4
Posted By: still_walkin
Subject: what is the big 4
Date Posted: December 18, 2007 at 2:34 AM
I read about the big 4 on another forum big it didn't descibe what is was . I know the big three could someone explain. Here the link where I found it
https://www.the12volt.com/installbay/forum_posts.asp~TID~49445~PN~1
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Replies:
Posted By: haemphyst
Date Posted: December 18, 2007 at 9:49 AM
I think what Rob was referring to was a ground bond between high resistance ground points and the battery return. The Big 3 refers to:
1: The alternator.
2: Underhood wiring, including chassis and engine block ground.
3: The battery
(Not necessarily in that order, though... They all need to be addressed, so the order doesn't matter, as they are all equally important.)
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: DYohn
Date Posted: December 18, 2007 at 9:59 AM
Actually the Big 3 refers to upgrading the three main wring components of any vehicle's electrical system, the cables between the alt and the battery, between the battery and the chassis, and between the engine and the chassis. Rob's "big 4" comment is adding a ground return lead from the amp to the battery if the vehicle's chassis return resistance is too high. ------------- Support the12volt.com
Posted By: still_walkin
Date Posted: December 18, 2007 at 1:50 PM
So basically instead of grounding the amp to the chasis he ran a wire directly to the battery. If a ground is to be only 3ft or less is that safe if he ran a ground from front of the vechile to back I'm lost. Is it worth doing
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: stevdart
Date Posted: December 18, 2007 at 4:51 PM
Distance of ground wire, as you said "If a ground is to be only 3ft or less", is only a recommendation. It is for the novice to understand that he must keep resistance at a minimum, and emphasizes that the entire chassis metal is conductive ground. DYohn's reply explains why and when you would consider running a ground wire home run instead of using the chassis. As for your question of safety: If a ground return wire is damaged it could contact metal, but the metal is also ground. Quite different than having a nonfused power wire contact ground. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: still_walkin
Date Posted: December 18, 2007 at 9:11 PM
So is it worth it. So instead of wiring the cars chasis he was wiring directly to the negitive post on the battery.
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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
Posted By: DYohn
Date Posted: December 18, 2007 at 9:22 PM
Measure your chassis return resistance to know if you need to do it or not. ------------- Support the12volt.com
Posted By: aznboi3644
Date Posted: December 19, 2007 at 1:13 AM
My wiring upgrades are a bit overboard.
-Alt to battery
-battery to body (about 3-4 ground straps)
-body to frame
-alt casing to engine block..then from there daisy chain to the battery
still have to do battery to frame
Posted By: still_walkin
Date Posted: December 19, 2007 at 5:46 AM
So did it work. Before you upgraded the ground from the amp to the battery did you notice a difference or not.
Posted By: DYohn
Date Posted: December 19, 2007 at 10:11 AM
If you need it, yes it's worth it. If you don't, probably not worth it. FIRST you need to determine if you need it. Did you understand that part of the post you quoted? ------------- Support the12volt.com
Posted By: djrn
Date Posted: December 19, 2007 at 3:03 PM
basicly if your trunk is not a suitible ground that would be the only reason to do a return ground to front chassis. u want the least amount of resistance in your ground to begin with.. with longer wire you get more resistance. but on some trunks the capacity of the metal in the trunk is not good enuf or is not bonded well enuf to handle alot of current. and you really only concerned about that anyways if you are pushing alot of current to the rear. i doubt that you would ever need to do that if your just feeding a 4 awg wire to the rear.
Posted By: DYohn
Date Posted: December 19, 2007 at 5:13 PM
It's not current capacity that is the limiting factor, it's return resistance value. Measure the return resistance from the amplifier ground to the alternator case. ------------- Support the12volt.com
Posted By: aznboi3644
Date Posted: December 19, 2007 at 6:27 PM
still_walkin wrote:
So did it work. Before you upgraded the ground from the amp to the battery did you notice a difference or not.
On my Explorer...the upgrades were a HUGE improvement.
Before the upgrades my voltage would drop from 13.6 volts down to 12.4 volts with a 460 watt rms Jensen amp...thing is even if I paused the music the voltage would not recover unless I revved the engine.
Now I after the upgrades my voltage idles at around 13.8-14.2 volts and drops down to only 12.6 BUT it recovers right back to 12.8-14.2 volts immediately after the bass hit.
IMO it was the most worthwhile upgrade I've done...also cheap too
Posted By: still_walkin
Date Posted: December 19, 2007 at 6:50 PM
How do you determine that it ios needed. I have a 0 guage ground in the trunk that seperates to three amps 4 guage output I have a 0 guage vacant. Can I use the negitive from the battery to the vacant zero guage on my distro block . Alos if I added for say a double ground on the back of the car and wired it to the same distro block will that make a difference.
Posted By: DYohn
Date Posted: December 19, 2007 at 9:02 PM
Read Rob's post that you referred to in your first message. Use an ohm meter. Measure the resistance between your amplifier ground point and the negative battery terminal, or better yet between the amp and the alternator case. ------------- Support the12volt.com
Posted By: n2audio
Date Posted: December 19, 2007 at 11:12 PM
aznboi3644 wrote:
-alt casing to engine block..
Why would you do this? Is your alt not already attached to the engine via large bolts and/or brackets?
Posted By: still_walkin
Date Posted: December 19, 2007 at 11:36 PM
djrn] wrote:
basicly if your trunk is not a suitible ground that would be the only reason to do a return ground to front chassis. u want the least amount of resistance in your ground to begin with.. with longer wire you get more resistance. but on some trunks the capacity of the metal in the trunk is not good enuf or is not bonded well enuf to handle alot of current. and you really only concerned about that anyways if you are pushing alot of current to the rear. i doubt that you would ever need to do that if your just feeding a 4 awg wire to the rear.
Well its possbile that my trunk may have enough resistance I drive an older cadillac which is more metal than fiberglass. On your question on the wire response. I have my amps receiving 4 awg wire but the power wire from the battery is 0 awg. My 3 amps are (1) 1600 rms and (2) 100 rms amps. I thinking by the upgrade I might get more bang out my amps. The perform well but if it will make them perform and not make the charging system work as hard then I'm all for it ;)
Posted By: DYohn
Date Posted: December 20, 2007 at 8:27 AM
still_walkin, I wonder if you've even read my posts? What is your ground return resistance? ------------- Support the12volt.com
Posted By: still_walkin
Date Posted: December 20, 2007 at 10:43 AM
I read it I haven't seen what the resistance is. Seem like a waste to run a new ground throuh the car and not like the results but so far everyone on this post liked the results so I guess I need to check the resistance them?
Posted By: DYohn
Date Posted: December 20, 2007 at 2:56 PM
still_walkin wrote:
I read it I haven't seen what the resistance is. Seem like a waste to run a new ground throuh the car and not like the results but so far everyone on this post liked the results so I guess I need to check the resistance them?
Yes. ------------- Support the12volt.com
Posted By: DYohn
Date Posted: December 20, 2007 at 2:58 PM
n2audio wrote:
aznboi3644 wrote:
-alt casing to engine block..
Why would you do this?Is your alt not already attached to the engine via large bolts and/or brackets?
Yes, in most cases, but that does not mean the bolts provide a good ground return path. The alternator casing is the "true ground" in your charging system. ------------- Support the12volt.com
Posted By: forbidden
Date Posted: December 20, 2007 at 3:49 PM
99% of installers and pretty much every single DIY guy on the block does not measure the return resistance reading. This needs to be done to ensure that you have a good ground. Again, a good ground is not necessarily the closest bolt in the trunk of a car. Take the time and meter the return resistance, then post the results.
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Top Secret, I can tell you but then my wife will kill me.
Posted By: hardwarz
Date Posted: December 21, 2007 at 1:27 PM
still_walkin wrote:
So is it worth it. So instead of wiring the cars chasis he was wiring directly to the negitive post on the battery.
It's worth it if you have real ground loop problems. Sometimes it might be your only solution to that kind of problem. Search for ground loop if you need more help on that topic. Hardwarz
Posted By: aznboi3644
Date Posted: December 22, 2007 at 3:56 PM
DYohn] wrote:
n2audio wrote:
aznboi3644 wrote:
-alt casing to engine block..
Why would you do this?Is your alt not already attached to the engine via large bolts and/or brackets?
Yes, in most cases, but that does not mean the bolts provide a good ground return path. The alternator casing is the "true ground" in your charging system.
Indeed...I grounded the alternator to the battery negative with 0 gauge wiring....This is a better ground path than between the alternator bolts and the grit and grime that is between the bolt and threads
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