So I have a pair of 12 inch subs with an 1800 watt amp pretty much sucking my car dry every time I crank up the volume. I'm getting pretty harsh voltage drops, down to about 12.5 volts when I really let them slam, and it causes the subs to cut out because the amp isn't getting enough juice. I've been looking into getting a new high output alternator, but it seems like it would be a lot cheaper if I could just install a second one that I could scrounge from the local junkyards. Note that my alt isn't dying, it still puts out a solid 14.4V, it just doesn't have the power to put out what I need by itself.
I think there might be space under the current alternator, but I was just wondering if anyone has done this before or has some wisdom on how to do it, the engine bay is pretty freaking cramped as it is already. I wouldn't mind cutting up my own brackets if I have to, but if there is some kind of kit out there it would definitely be nice. I've done some poking around but can't seem to find any.
So, any thoughts?
2001 Infiniti QX4 Dual Alternator
Re: 2001 Infiniti QX4 Dual Alternator
Im pretty sure Im literally the only one in the world (atleast documented on the internet) that has done a dual alternator setup on the qx4. I placed it right above the a/c compressor (stock intake box/resonator removed for a custom piece to save room there) and ran a custom length belt and tensioner on the a/c belt system. But I was running upwards of 7000 rms watts, and 6 batteries at one point.
For 1800 watts you surely dont need a second alternator, its far to much work and expense, the 110amp stock alt can more than handle that, youre problem is your battery bank or lack of it. A proper second battery and "big 3" wiring upgrade will make a world of difference for you. You can even easily fit a second battery underhood if you run a custom intake, lots of room once you ditch the factory air intake boxes.
If youre set on needing more alternator power, mechman sells a drop in 300amp unit for about $400 to replace the stock piece.
I do custom car audio for a living, mainly competition suv systems, so I can definitely point you in the right direction to doing it right and efficient the first time.
For 1800 watts you surely dont need a second alternator, its far to much work and expense, the 110amp stock alt can more than handle that, youre problem is your battery bank or lack of it. A proper second battery and "big 3" wiring upgrade will make a world of difference for you. You can even easily fit a second battery underhood if you run a custom intake, lots of room once you ditch the factory air intake boxes.
If youre set on needing more alternator power, mechman sells a drop in 300amp unit for about $400 to replace the stock piece.
I do custom car audio for a living, mainly competition suv systems, so I can definitely point you in the right direction to doing it right and efficient the first time.
Re: 2001 Infiniti QX4 Dual Alternator
I was thinking about getting a marine battery and throwing that in the trunk with an isolator, and re wiring the whole thing with 0 gauge wire, you think that and the big 3 will be enough? Also TBH I think that the amp is 1800 watt peak, ~1K RMS. I am just running on the stock battery currently.
Re: 2001 Infiniti QX4 Dual Alternator
Skip the isolator/capacitor, complete waste if you want to play music for more than 3 seconds. Look for an AGM ( absorbed glass mat ) battery, avoid the generic lead acid batteries, and buy the biggest size you can afford and fit. ($200 will buy you a good battery, $300 will buy you some overkill/headroom)
The big 3 makes a world of difference on stock alternator systems, highly suggest you do that first, even before a new battery if your on a tight budget, worst case scenario your battery still cant cut it and you use the same new wiring on the new battery anyways, for under 2000rms I wouldnt waste the cargo space and wiring troubles running big cable to the rear, just upgrade the stock battery in stock location.
To save money on wire aswell, almost all welding stores sell oxygen free copper wire by the foot, 0 gauge being about $2 usually. Much better cable than the common 0 gauge on the market, if this isnt a show car, welding wire is the way to go, comes with a plain black very thick jacket and is very flexible and high quality. If you want the fancy jacket stuff, do a few minutes of research and be sure the wire your buying is copper and not copper clad aluminum.
The big 3 makes a world of difference on stock alternator systems, highly suggest you do that first, even before a new battery if your on a tight budget, worst case scenario your battery still cant cut it and you use the same new wiring on the new battery anyways, for under 2000rms I wouldnt waste the cargo space and wiring troubles running big cable to the rear, just upgrade the stock battery in stock location.
To save money on wire aswell, almost all welding stores sell oxygen free copper wire by the foot, 0 gauge being about $2 usually. Much better cable than the common 0 gauge on the market, if this isnt a show car, welding wire is the way to go, comes with a plain black very thick jacket and is very flexible and high quality. If you want the fancy jacket stuff, do a few minutes of research and be sure the wire your buying is copper and not copper clad aluminum.
Re: 2001 Infiniti QX4 Dual Alternator
The subs already take up a lot of the space in the rear anyway and there is a good amount of space right next to the subs that is already being wasted. I wasn't thinking about a cap but an isolator keeps the main battery charged therefore not stressing the engine, and charges the auxiliary battery when there is extra power, correct? Or is the difference negligible in terms of stress on the engine? That is all I'm really worried about, currently the RPM's jump whenever I hit a low note. I'll post a pic of what I was thinking.
I'd also need a new fuse if I run 0 gauge wire right? Any suggestions? Not a show car all I care about is how loud it is, louder being better. >:)
Edit:
Here it is, was thinking of shoving a battery in-between the subs and the wheel well on the right.
I'd also need a new fuse if I run 0 gauge wire right? Any suggestions? Not a show car all I care about is how loud it is, louder being better. >:)
Edit:
Here it is, was thinking of shoving a battery in-between the subs and the wheel well on the right.
Re: 2001 Infiniti QX4 Dual Alternator
Would you happen to have any pics of your dual alt setup?
CanuckQx4 wrote:Im pretty sure Im literally the only one in the world (atleast documented on the internet) that has done a dual alternator setup on the qx4. I placed it right above the a/c compressor (stock intake box/resonator removed for a custom piece to save room there) and ran a custom length belt and tensioner on the a/c belt system. But I was running upwards of 7000 rms watts, and 6 batteries at one point.
For 1800 watts you surely dont need a second alternator, its far to much work and expense, the 110amp stock alt can more than handle that, youre problem is your battery bank or lack of it. A proper second battery and "big 3" wiring upgrade will make a world of difference for you. You can even easily fit a second battery underhood if you run a custom intake, lots of room once you ditch the factory air intake boxes.
If youre set on needing more alternator power, mechman sells a drop in 300amp unit for about $400 to replace the stock piece.
I do custom car audio for a living, mainly competition suv systems, so I can definitely point you in the right direction to doing it right and efficient the first time.