The Big 3 = upgrading alternator wiring, battery wiring,engine to chassis ground wire

Hey guys. ive installed a stereo system in my car and its rather large. two 12" speakers and a 1000W amp. the guys on the car audio forum figure that that setup with my stock 120 amp alternator shouldnt make my lights dim, and that I need to possibly upgrade "the big 3"

big 3 info here: http://www.caraudioforum.com/showthread.php?t=352271

basically what it is is upgrading, or adding another wire to 3 spots:

1. from the alternator to the battery positive
2. from the battery negative to where ever it grounds to
3. from the engine block to the frame, or whevever it grounds to.

I dont plan on removing any wiring, just adding an existing wire to each route.. so theres basically 2 cables going from the alternator, to the battery. 2 cables from the battery negative to the grounding spot, etc...

my question is, how hard are these to access? is it a simple and easy job, or is it going to be an all day thing getting to the alternator output stud and accessing the positive and negative cables all around the car?

what scares me the most is the engine to frame grounding strip... where is that and how hard is it to access?

thanks!

I would say all that you have to do is pull the battery and tray. The grounds are under the tray. I believe one of the larger ones runs up to the battery.

The main battery ground runs to the top of the bell housing, easy to spot and not too bad to get to.

I haven't traced the the alternator wire, but it shouldn't be too bad other than possibly digging it out of a loom. I assume it runs up to one of the big fuses on top of the battery.

There is pre-made upgrade cables available, serious gear.

Depending on hop long you crank it you may not need a larger alternator. Keep in mind you don't have an ignition system and much less fuel system electrical draw than most of the guys on a car audio forum.

pre made specifically for the Jettas?

I dont think I need a larger alternator, I think my problem is either "the big 3" wiring, or my ground location. the light dim instantly on every single loud bass pound.

The stock alternator wire is rated for 150A and the alt is rated for 120A. Unless one of the connectors has a poor connection(which does happen), you will be wasting money upgrading the wires.

Sounds like all you need is a capacitor to smooth out the ripple. The flickering is caused by the voltage regulator constantly trying to adjust to the different loads.

http://forums.tdiclub.com/showthread.php?t=273859

At low voltages there is no such thing as to much copper.

My lights are brighter, everything electrical works better than it did with good factory cables.


A good way to find voltage drop is with an analog meter set to around 2 volts attach one end to the negative terminal of the battery with everything cranked as old as you want to rock out and then probe along at each point along the way and watching to see if you have any sudden jumps in voltage.
Putting a volt meter on the lead portion of the battery is probably where you should start to see if your pulling the actual battery down or not.

If you have access to a thermal camera it is a great tool for inspecting wiring. Issues light up like a flare in the night.

I haven't done hard core car stereo since 1999 (in an air cooled VW bus), but the general theory is still the same.

Lol.
I'm sorry
Autocorrect changed LOUD to OLD.

I hope you find as much humor it this as I do.

turbocharged798 said:

The stock alternator wire is rated for 150A and the alt is rated for 120A. Unless one of the connectors has a poor connection(which does happen), you will be wasting money upgrading the wires.

Sounds like all you need is a capacitor to smooth out the ripple. The flickering is caused by the voltage regulator constantly trying to adjust to the different loads.

Click to expand...

ah man, I hope thats not true. I just spent 70$ USD / 100$ cad on a ton of new cables!!





1x red 1/0 terminal to go to the alternator output lug.
1x dual 1/0 battery terminal for the positive lug on the battery
3 feet of red 1/0 cord

2x black 1/0 terminals for the engine to chassis ground
3 feet of 1/0 cord, might be extra, better than being too short.

1x black 1/0 terminal to ground to the frame from the battery negative
1x dual 1/0 battery terminal for the negative lug on the battery
3 feet of 1/0 cord.

I just read in another thread that the alternator output lug to the battery positive terminal should have a fuse in it... what do you guys think about that? straight wiring it is a bad idea?

if I needed a fuse, what size would you recommend?

this is sure getting complicated/pricey just to have loud music and no headlight dimming/alternator damage!!

"but I have a concern about the alternator wiring. A second cable from the starter solenoid to the alternator output effectively bypasses the alternator fuse. Follow the two paths: 1 Battery + to fuse to alternator. 2 Battery + to starter to alternator. Path 2 will continue to carry current even if the fuse could blow!"

"I for one would not run the cable from the alternator to the battery without some sort of fuse or fusable link."

Mine has been unfused for 4 years, haven't failed yet.
But, yeah a fuse is a great idea.

does the stock wire from the alternator to the battery positive have a fuse?

if so, what size?

guess ill find out when I get the parts and install the wires for the big 3 eh.

Yes, factory fused in plastic box on top of battery. I think it is a 150 amp, but I really don't remember.

Check out http://www.bulkwire.com/wireresistance.asp if you would like to see what running heavier cable will do in a car.

turbocharged798 said:

The stock alternator wire is rated for 150A and the alt is rated for 120A. Unless one of the connectors has a poor connection(which does happen), you will be wasting money upgrading the wires.

Sounds like all you need is a capacitor to smooth out the ripple. The flickering is caused by the voltage regulator constantly trying to adjust to the different loads.

Click to expand...

The stock alternator wire is not rated for 150 amps lmao! the fuse rated for that. fuses always rated higher then wiring otherwise the fuse would blow every time you had a bunch of **** running at once.

wire has ratings, depends on the thickness.

Wire resistance calculator says that stock wire should loose 0.48 Volts so at 150 amps (that will probably never happen) what you would have is a 72 watt heater between the alternator and the fuse box.

sparkeez said:

The stock alternator wire is not rated for 150 amps lmao! the fuse rated for that. fuses always rated higher then wiring otherwise the fuse would blow every time you had a bunch of **** running at once.

wire has ratings, depends on the thickness.

Click to expand...

Nope, you have that backwards. The fuse is there to protect the wire and based on wire size. If the fuse was rated higher than the wire you would have an instant fire if a short developed somewhere.

turbocharged798 said:

Nope, you have that backwards. The fuse is there to protect the wire and based on wire size. If the fuse was rated higher than the wire you would have an instant fire if a short developed somewhere.

Click to expand...

Someday you will look on this post and hang your head in shame. but just remember that I think you are great!

dremd said:

Check out http://www.bulkwire.com/wireresistance.asp if you would like to see what running heavier cable will do in a car.

Click to expand...

Are you saying that running heavier wire. Like 1/0 for the big 3 is bad?

If I get a 2000 watt amp. On a 13-14 volt system. That should be roughly a 150 amp draw right?

fouillard13 said:

pre made specifically for the Jettas?

I dont think I need a larger alternator, I think my problem is either "the big 3" wiring, or my ground location. the light dim instantly on every single loud bass pound.

Click to expand...

This site has the best cables pre-made for your VW. I replaced my alternator to fusebox cable and it was well made.

http://innovativewiring.com/?page_id=161

sparkeez said:

Someday you will look on this post and hang your head in shame. but just remember that I think you are great!

Click to expand...

What I said is accurate, you are welcome to research it.

dremd said:

http://forums.tdiclub.com/showthread.php?t=273859

At low voltages there is no such thing as to much copper.

My lights are brighter, everything electrical works better than it did with good factory cables.


A good way to find voltage drop is with an analog meter set to around 2 volts attach one end to the negative terminal of the battery with everything cranked as old as you want to rock out and then probe along at each point along the way and watching to see if you have any sudden jumps in voltage.
Putting a volt meter on the lead portion of the battery is probably where you should start to see if your pulling the actual battery down or not.

If you have access to a thermal camera it is a great tool for inspecting wiring. Issues light up like a flare in the night.

I haven't done hard core car stereo since 1999 (in an air cooled VW bus), but the general theory is still the same.

Click to expand...

I also got those wires....it cranks much faster....which is great since I live at a higher altitude and it is always come.

Dude, why didn't you just buy a cap? That is what they are for.

dremd said:

Yes, factory fused in plastic box on top of battery. I think it is a 150 amp, but I really don't remember.

Click to expand...

Also, the connection of the alt wire to the lug at the battery top fuse box often fails. Gets corroded inside the end of the wire and resistance goes up leading to heat, fires, melted plastic, blown fuses. I replaced the wire in my 03 with welding cable. Cheap easy effective.

My son has a similar stereo setup in his 00 golf. He put in a big capacitor which fixed his dimming lights issue. That is all I know about car stereos.

I was told by the guys on the car audio forum that a capacitor not only is something you generally want to avoid (guess its a band aid type fix), but its something that wouldnt be able to handle the 2000 watt amp that im considering for my constant 4 hour drives, and at that point, its just another item pulling electricity from my already taxed alternator.

im gonna do this wiring and change my amps grounding location, and see how it goes from there.

I will then test the system with a multimeter to see how many amps im pulling.

at that point ill consider getting a capacitor if needed.

belome said:

Dude, why didn't you just buy a cap? That is what they are for.

Click to expand...

heres some reading and interesting points I found regarding capacitors on a car audio forum:

-------------------------------------------------------------------------

how much energy is stored in a typical 12v 100 amphr deep cycle battery?

Answer?

4,320,000 Joules

Do you know how much energy it takes to charge a 100 Farad Cap from 0-12v?

Answer?

14,400 Joules


------------------------------------------------

100 farads isnt really much power at all. Reletively speaking, it is almost nothing. A 2000mAh AA rechargable battery has the same power as a 7,200 FARAD cap (at only 1.2v) So you may think thats alot of power, but if you know from experience, AA batteries arent going to be starting your car.

------------------------------------------------------

A car battary has millions of Farads of capacitance and a top of the line performance battery only runs around 200$. Therefore when the cost of capacitors reaches 200$ you switch to batteries

--------------------------------------------------

Now about brands, yes it does matter, all caps are different, but they rarely tell you the ESR (rated in ohms) but if they do, the lower the better. Dont get one of those 'digital' ones with snazzy volt meters on them, they suck. Get a basic cap around 2 farads and up.

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most of the time having a cap in a car sound system is just a "wank factor"
those large capacitors and battcaps are total BS.
the ESR is far too high to be effective with them, using carbon based capacitor banks internally.
total junk.
capacitors don't help voltage rails anyway.
the only things a capacitor will do is reduce propogation delay and filter AC ripple
neither you're likely to notice anyway
I really don't see much use for these things otherwise...... other than lining the pockets of certain mobile audio manufacturers and sales personnel.

All I know is my son installed a cap and his lights quit dimming with the subs.

sdeck said:

All I know is my son installed a cap and his lights quit dimming with the subs.

Click to expand...

Yup. I don't recall how big my cap was (it was about the size of a tennis ball container) but it took care of the dimming for sure.

I was however getting good at replacing lifetime autozone alternators. I'm sure I was good for about 1 a year.

Sounds whoever wrote that above statement on caps has no clue how they work. Comparing them to deep cycle battery? That is borderline retarded.

A cap work by smoothing out the short term current spikes. Alternators do not like quickly changing loads and thus your lights dim when the load is suddenly increased. When you add the cap, it smooths out the sudden current change and allows the alternator to do its job more effectively.

turbocharged798 said:

Sounds whoever wrote that above statement on caps has no clue how they work. Comparing them to deep cycle battery? That is borderline retarded.

A cap work by smoothing out the short term current spikes. Alternators do not like quickly changing loads and thus your lights dim when the load is suddenly increased. When you add the cap, it smooths out the sudden current change and allows the alternator to do its job more effectively.

Click to expand...

I dunno... thats coming straight from a car audio forum. those guys know what theyre talking about. ive been told, and read, by several guys that caps are a band aid fix.

my system would have a cap drained in about 10 minutes. at that point, its just another item drawing electrical from my already taxed alternator.

also...

"there isn't any way that your stock alternator wiring is rated for 150 amps. Conveniently, the minimum fuse rating for a 120amp alternator is 150 amps. Fuses are rated at a minimum of 125% of the current that any given wire is intended to carry.

I think whoever told you that is confusing the fuse rating with the ampacity of your alternator wiring."