The Big 3

[Fi-brations 10+ year member]

I know this is a fairly simple concept, but in my situation it gets a little more difficult. So im lookin for some ideas and advice to tackle this.

I have a 2000 BMW 528i, and my battery is located in my trunk not under my hood. I am running a total of 1500watts for the whole system, and my voltage is dropping as low as 11.3 at some points! I know I can upgrade the battery's ground to 0 gauge, but how would i upgrade the ground for the engine to the battery? I've heard over 3 feet for a ground is a "no no" so im lost there. Also, running somewhere around 20 ft of 0 gauge for the alternator to the battery doesnt sound good to my wallet, and i believe the wire for that is factory 2 gauge already. What can I do? My battery is pretty large, the only spec on it I know is that it has 1000 cranking amps, would upgrading to an even larger battery help? If so what group should i get? thanks,

and on a side note: what type of 0 gauge would i get? i know knuconceptz has it, but there are a few different types

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[Tek18 10+ year member]

the flex from knu is cheapest //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif thats what i got and i'm installing this weekend. ( thats as far as i can help ya )

but look up big 3 on youtube, its a big help

 

[kramer_212 10+ year member]

your alternator grounds, on the engine block i would run a 1/0 power cable from the alternator to the rear battery, and do a 1/0 ground for the rear bat and amps also, this should be fine.

 

[kramer_212 10+ year member]

oh and as far as batterys if you have room do multiple agm batterys i recommend kinetik because i use them in all my cars, and motorcycles and having below 0 degree weather still have had no failure.

 

[Tek18 10+ year member]

wait i thought it was the big 3, why ground the alt ? ( big 4? )

 

[WheresTheButta 10+ year member]

definitely upgrade the stock power wire from the alternator to the battery - replace it with 0 gauge.

In addition, improve the engine block (or alternator case) to chassis ground, and the battery to chassis ground. Use 0gauge for all of it.

Knukonceptz is good stuff, but I would definitely use their real copper wire instead of the "cca" stuff.

 

[Tek18 10+ year member]

i heard using CCA doesn't matter if your unde like 3000 RMS or something, 10000 RMS one of the 2 haha ( little differnce ) at his 1500 i think he's fine

 

[BnGRacing 10+ year member]

The 'big 3' is not going to magically bump up your voltage another 3v. In many cars it's a complete waste of time and money but it gets repeated over and over in online forums and people start to believe it.

Do the wires going to your battery get warm? Probably not. If that's the case, you can spend a couple hundred bucks on nice fire hose copper wiring and connectors while not improving a thing. 1/0 is a waste and don't listen to anyone who says otherwise. You know if you add a run of 4ga in addition to the factory wiring it'll have **** near the same resistance as 1/0, right? Marketing departments prefer to sell dumb kids 1/0 though as there's a ton of markup in accessories even though two runs of 4ga will be less expensive and perform just as well.

If you want to get rid of your dimming and your charging system is in good order; turn your subsonic up and your gain down. There's a good chance that you're clipping the amp and turning down the gain will reduce that wasted energy. In addition, a subsonic will make your amp a bit more efficient as it will not be drawing current to reproduce freq. you can't hear & your subs can't play. Furthermore, your car is terrible for bass and BMW owners experience diminishing returns much more quickly than other cars. If worse comes to worst; buy a cap. A good capacitor will help dimming with normal music but will be rather useless with bass tracks, sine sweeps, and drawn out notes. If anything, it'll help keep a more stable voltage going into the power supply and filter noise. Used Stinger caps can be had for around $30.

Like "the big 3" mantra, plenty of people will chime in saying caps are worthless. They've heard this over and over and are just repeating what they heard. A good cap can help dimming and they've done so for many people. I had a car with a surfboard amp + cap and the lights didn't dim to the music at all. No "big 3" and I even had underdrive pulleys. And if you think about it for a bit; if caps are so useless why are they used in 100% of quality amps?

If I were in your shoes, I'd try playing with amp settings and verify that this isn't an install related issue. Something as simple as not using a star washer or grounding to a bad piece of metal can cause this issue. Unlike 20' of 1/0 copper, turning a few knobs & checking the ground is free.

 

[Fi-brations 10+ year member]

my amps are grounded straight to the battery, and im going to set all my gains properly this weekend(already on my agenda) i have 4 gauge for my sub amp, it doesnt get hot, havent ever checked the factory wire from the alt to the battery while my subs had been playing, cause it's under my rear seat, what do u mean my car is bad for bass? it doesnt handle it well, or it doesnt produce it well?

 

[THATpurpleKUSH 5,000+ posts]

How big is your alternator? If your voltage is dropping that low, its time to back off the volume until you have the electrical to support it. Sustained low voltage to an amp will cause it to clip even if the gains are set right and will shorten its lifespan. Adding a second battery will help stabilize the voltage. Look into AGM style batteries in the 30-50amp hour range.

 

[KyleBechtold 5,000+ posts]

the flex from knu is cheapest //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif thats what i got and i'm installing this weekend. ( thats as far as i can help ya )
but look up big 3 on youtube, its a big help

no its not.. Knu is 3.95 a foot.. thats $1.20 higher than good 1/0 welding wire.. its .40 more than 2/0 so..?

 

[esmokah 10+ year member]

You drive a BMW and worry over the price of a piece of wire?

 

[KyleBechtold 5,000+ posts]

You drive a BMW and worry over the price of a piece of wire?

A used bmw can be had for pennies on the dollar.. especially a 12yr old one

 

[esmokah 10+ year member]

so what you're saying is that it's paid off. i stand by my previous comment.

Do the big 3. you gotta rule out the horses before you rule out the zebras.

 

[Ninesvnsicks 10+ year member]

Welding cable is cheap you can get 25ft rolls for $50. Check your local AirGas if you have to get #1 it's not that much smaller than 1/0.