Big 3 Failure/massive voltage drop/tips?

[FML 10+ year member]

Hey guys.

 

Made a post earlier in the week asking a couple questions regarding Big 3 upgrade. Well, I completed it today. To say im disappointed would be an understatement. Ill take you through my setup, how I did it and ask for advice.

 

I ran 0 gauge from alternator positive to battery positive, battery negative to ground (frame rail that I used an electric grinder/sander on) and engine (i chose a bolt of alternator), to the same ground area on the frame rail. Not on top of one another, but about an inch or two apart.

 

After completing my install, I have ZERO improvement. Normally, first thing in the morning (prior to big 3), my voltage at my amps would be 14.6. Same now. But, I get massive voltage drops into the upper 10s to 11s, and my lights still go bonkers in and outside of the truck.

 

I realize im running not only 1, but 2 pretty power hungry amplifiers(RF T10001BD bass amp AND a JL 450/4 for components) but still. Im also still keeping my capacitor in line for the bass amp.

 

So, im stumped. Did I miss something here? I see most people run engine ground right to battery negative. But it's all the same, as long as its grounded, no? Is my alternator toast? Can I do anything about it? New HO alternator isn't in the budget currently. Runs around $600 for my truck.

 

Im just at a loss. Any help, tips, would be appreciated. Thanks!

 

EDIT. ALSO, I BELIEVE STOCK ALTERNATOR IS 110 AMPS. BATTERY IS FAIRLY NEW, 810 CCA

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[los33]

You do know the alternator grounds at those bolts right?

 

[FML 10+ year member]

You do know the alternator grounds at those bolts right?

Not.sure what you mean by that. But obviously the alternator grounds thru the engine to the ground location. I made the path shorter by making a run directly off its case.

 

[los33]

Not.sure what you mean by that. But obviously the alternator grounds thru the engine to the ground location. I made the path shorter by making a run directly off its case.

Alternator grounds does not ground the engine block. If anything it will ground most of the alternator power and less of what the engine block.

Your best off using the stock location for the engine block.. The frame ground can be anywhere on the frame.

 

[mylows10 5,000+ posts]

Also. Grounds are. Battery to block. Battery to frame. And if needed batter to alt pos battery to pos alt. What truck. Also dump the cap

 

[gckless 5,000+ posts]

What are you wired to, at each amp? If at 1ohm, I'm not surprised you're dropping that low.

 

[big scott]

Alternator grounds does not ground the engine block. If anything it will ground most of the alternator power and less of what the engine block.
Your best off using the stock location for the engine block.. The frame ground can be anywhere on the frame.

alt. ground throw the engine. most will make a ground from back of alt. to frame/battery.

thats how i have mine. there's a bolt for a ground on the back of mine. if yours does not have that then ground at the alt. mounting bolt.

dont replace any ground, just add the big 3 . also put that ground on the frame in the same spot. you say its about an 1" apart... put them on the same bolt. as you can get ground noise.

also you will not get more power just by adding the big 3... all that does is allow the current to pass easier. power is made by the alt. so if your getting dimming lights you need a bigger alt.

 

[big scott]

also did you put a fuse holder/fuse on the alt. to battery + ??

if not do so.

 

[los33]

 

EDIT. ALSO, I BELIEVE STOCK ALTERNATOR IS 110 AMPS. BATTERY IS FAIRLY NEW, 810 CCA

For daily driving in my 2000 gmc sierra 1500 i run a 105amp alt with a oreily super start agm.

Current amps are cerwin vega v400.4 and vfl 4480 which does near or more then 2000 watts.

My voltage drops between 11.8-12.5 during idle at full blast and hover around 12.8-13.4 during 1200 rpm.

So you must have a ground issue.

alt. ground throw the engine. most will make a ground from back of alt. to frame/battery.thats how i have mine. there's a bolt for a ground on the back of mine. if yours does not have that then ground at the alt. mounting bolt.

dont replace any ground, just add the big 3 . also put that ground on the frame in the same spot. you say its about an 1" apart... put them on the same bolt. as you can get ground noise.

also you will not get more power just by adding the big 3... all that does is allow the current to pass easier. power is made by the alt. so if your getting dimming lights you need a bigger alt.

Newer truck alts dont have a ground bolt so they ground thru the mount bolts, but like my bolts stick out 1/4 inch so a lug would not have full contact so i am forced to bolt directly to the block.

 

[big scott]

For daily driving in my 2000 gmc sierra 1500 i run a 105amp alt with a oreily super start agm.
Current amps are cerwin vega v400.4 and vfl 4480 which does near or more then 2000 watts.

My voltage drops between 11.8-12.5 during idle at full blast and hover around 12.8-13.4 during 1200 rpm.

So you must have a ground issue.

Newer truck alts dont have a ground bolt so they ground thru the mount bolts, but like my bolts stick out 1/4 inch so a lug would not have full contact so i am forced to bolt directly to the block.

ya thats fine. but best to get as close as you can to the alt. back of alt. ,, mounting bolt at alt. ,, alt. bracket at engine......

hell if you have enough room on the alt. bracket drill a hole and put the lug there. and some will say it does not matter but if your going to do the big 3 you want to pick the best mounting spots. plus less Resistance .

also to op...

if you were not getting that voltage drop before the big 3 then thats your problem.... make sure all grounds are on the same bolt,,,, keep all stock grounds just add the bigger wire.

also get your alt. checked to see if its putting out. make sure your grounds at the amps are on the same bolt...

 

[FML 10+ year member]

For daily driving in my 2000 gmc sierra 1500 i run a 105amp alt with a oreily super start agm.
Current amps are cerwin vega v400.4 and vfl 4480 which does near or more then 2000 watts.

My voltage drops between 11.8-12.5 during idle at full blast and hover around 12.8-13.4 during 1200 rpm.

So you must have a ground issue.

Newer truck alts dont have a ground bolt so they ground thru the mount bolts, but like my bolts stick out 1/4 inch so a lug would not have full contact so i am forced to bolt directly to the block.

alt. ground throw the engine. most will make a ground from back of alt. to frame/battery.thats how i have mine. there's a bolt for a ground on the back of mine. if yours does not have that then ground at the alt. mounting bolt.

dont replace any ground, just add the big 3 . also put that ground on the frame in the same spot. you say its about an 1" apart... put them on the same bolt. as you can get ground noise.

also you will not get more power just by adding the big 3... all that does is allow the current to pass easier. power is made by the alt. so if your getting dimming lights you need a bigger alt.

Thanks for the replies. The casing on my alt had a threaded hole on it with nothing in it. I found a bolt with the correct thread pitch, put a copper washer on it, and mounted my lug to it. Verified with a meter that its solid ground. Only reason I didn't choose factory engine ground, is the bolt is humongous. Would require a very large ring.to fit over it. Iv seen many install done this way, but if its incorrect, ill fix it.

And yeah, im running bass amp at 1Ω. My stinger volt meter comes of that amp.

And I realize I wont see more power, but with that bad of voltage drop, im shocked that my amps.don't go into protection. Especially the JL. Slash series amps are known to cut out under 12v. I don't know...just pretty stumped on this go.

 

[FML 10+ year member]

ya thats fine. but best to get as close as you can to the alt. back of alt. ,, mounting bolt at alt. ,, alt. bracket at engine......
hell if you have enough room on the alt. bracket drill a hole and put the lug there. and some will say it does not matter but if your going to do the big 3 you want to pick the best mounting spots. plus less Resistance .

also to op...

if you were not getting that voltage drop before the big 3 then thats your problem.... make sure all grounds are on the same bolt,,,, keep all stock grounds just add the bigger wire.

also get your alt. checked to see if its putting out. make sure your grounds at the amps are on the same bolt...

No, voltage drops were just as bad prior. Hence the reason for this thread

 

[los33]

Thanks for the replies. The casing on my alt had a threaded hole on it with nothing in it. I found a bolt with the correct thread pitch, put a copper washer on it, and mounted my lug to it. Verified with a meter that its solid ground. Only reason I didn't choose factory engine ground, is the bolt is humongous. Would require a very large ring.to fit over it. Iv seen many install done this way, but if its incorrect, ill fix it.
And yeah, im running bass amp at 1Ω. My stinger volt meter comes of that amp.

And I realize I wont see more power, but with that bad of voltage drop, im shocked that my amps.don't go into protection. Especially the JL. Slash series amps are known to cut out under 12v. I don't know...just pretty stumped on this go.

Stupid question...

But did you re adjust the volt meter after the big 3 using a multimeter and reading power at the amp?

When your bass hits measure the voltage at the battery terminals and see if you see the same voltage drop.

 

[FML 10+ year member]

I have not tested the voltage off the battery yet. And Im not aware of adjusting an aftermarket volt meter? Its the little stinger box shaped one, mounted on dash. Iv always just subtracted or added the variance from what meter displays and what my DMM reads.

 

[big scott]

you mounting the ground to the back of the alt. is great. keep it there.

like i said doing the big 3 is not going to stop your voltage drop. you need a h/o alt.