onspeed

My lights are dimming when I play music loud (Arc XDi805 and Pioneer double din), so I'm going to do the "big 3" mod and hope this solves the problem. Quick question I had though - I used a previously existing amp wiring to hook up the system, and the PO had wired the + wire to the terminal on the fusebox instead of directly on the battery. Is this something I should change? I'm thinking there might be a "bottleneck" on the wiring that connects the + terminal of the battery to the + terminal on the fuse box?

Also, I have a side-mount AC delco battery. I'm guessing the connectors will need to be changed to accommodate the additional wires? All the Big 3 pictures I see are using top-mount batteries, but my battery is relatively new and I don't really want to buy a new one. I'm planning to just use generic autozone battery cables to wire everything, this shouldn't be a problem right?

markcz

They should have a side-post adapter at autozone for adding wires to the battery.

You can move the amp wire, or just add a wire between battery and fuse terminal when you do the big 3.

pentavolvo

moving wire directly to battery may eliminate your dimming issues

markcz

Good point. OP, you can check how that would work in 30 seconds if you clip on a jumper cable between the B+ and fuse terminal, then crank up the tunes.

onspeed

Moved the amp wire directly on to the battery terminal and added the 3 wires. It still dims when the music is turned up and the song has a strong bass line, although it's not noticeable as it was before. Don't think I'm going to bother with a capacitor since I don't really crank the music super loud at night anyways.

One question I had though was what size fuse people were using for the alternator to battery cable. Lots of people said they were using 4ga wire with a 150amp fuse... doesn't this make the fuse almost useless? I think the wire would melt/catch fire before the fuse blows? Plus, since there's now 2 alternator wires and the alternator outputs ~110amp, wouldn't it be safer to use like a 60 or 80 amp fuse? I don't think a 110amp+ would be needed since the current would be split between the two wires.

markcz

I have 2g wire and a 250a fuse in mine

IMO the fuse is there more to protect the battery, alternator, wire, and car against a direct short if one end comes loose, not for constant-load over current protection. The smaller fuses are what protect the individual components.

onspeed

I'm noticing an alternator whine when the stereo is on now. I'm not sure if it was there before I did the big 3 mod or not.. But I don't see how adding lines would change anything though. I know when I installed the double din that I used the ground lead coming from the adapter harness. Is this possibly causing my problems?

markcz

If you can't fix the whine by moving ground cables, a pair of GLI's between HU and amp should take care of it. Some call them band-aides, but they work.

666WMD

First thing you should check is all of your ground wires. Make sure the amp ground is on bare thick metal, chassis or near to it is best. Pioneers are notorious for alt whine but also excellent sound quality, the two might be related. The usual fix for that problem is to ground the RCA terminals of the radio to the chassis of the HU. Just drop a blob of solder onto each terminal where it meets the chassis of the radio. Or if you don't have solder, get some 16 gauge wire and wrap it around each terminal separately and jam it into the gap between the RCA's and chassis. Changing the earth wire on the HU to a good point in the car will further help eliminate alt whine.

With your 4awg power wire, it should be fused at the battery for the current capability of the wire (150amp), and as previously mentioned, it's to protect all the car's electronics in case of a short. It should also be fused at the amp if the amp doesn't have onboard fuses for the current draw of the amp, ie: 10amps per 100wrms the amp is capable of. If the amp is a 4ch with 200wrms per channel @ 2ohm, you need an 80amp fuse.

onspeed

Could I ground the head unit to the cage?

markcz

In a round about way it already is.

If you're trying to eliminate the whine you need to connect the - wire of the sound output to the frame of the HU, or the cage, or directly to car frame, it's all the same, but directly to HU frame gets best results from what I've read.

If you have amp connected directly to battery, as mentioned check your ground cable for good electrical contact. If it's good I don't know what else you can do other than get a cap or better battery.