dual alternator setup

I don't see why it wouldn't work. It shouldn't be that hard to keep everything isolated from the factory electrical system - with the exception of grounding; that is where if you have a problem, it will lie. Since you will be using the metal chassis as your grounding medium(you will have to since the alternator will probably ground through it's case, through the engine block, and finally back to the battery), both batteries, and consequently electrical systems, will share the same ground.

I do not posess enough electrical knowledge to know what negative ramifications this would have, but it is an interesting topic of descussion. Hopefully someone else will chime in...

From a strictly technical standpoint, creating a 12v system like this wouldn't really be that hard. Engineering everything to fit would be incredibly difficult however.

I think the problem is that it is simply easier to beef up the primary electrical system.  I'm having a hard time imagining why building an entire secondary electrical system would be less expensive - or even materially easier - than dropping in a rewound alt and a new deep cycle battery.

It's not that it isn't possible, it just isn't practical or cost effective.

If building the bracket wasn't a problem, would having both alt's grounded through the frame pose a problem?

What if you could isolate the 2nd one from the frame -of course creating a very unique designed bracket- and have the amps/etc... grounded straight to it's case -via BIG cable? Is this practical, of course if they both can't be grounded through the frame?

Please excuse me. I'm trying to think hard again...

I highly doubt it'll bolt right in...

I can assure you that trying to graft a secondary, isolated 12v electrical system on top of your cars' existing electrical system will, all technical issues aside, cost you several times this figure.  Please remember, that you also have to add a second battery (unless that Red Top is a secondary, this is unclear from your posts) and all sorts of wiring.  I usually figure wiring runs up to 20% of a projected budget - this type of project might be significantly higher.

My understanding of traditional mutli-alt systems in limos and strech-Hummers or whatever is that they are wired in such a way to produce huge amperage at 12v - there isn't an isolated secondary system.

Seriously, I applaud your ingenuity and inventiveness here, but I think your trying to create something much more complex, expensive, and ultimately unreliable than you need.  You will not be able to simply hook up your amps to your new "drop-in" secondary alternator, and there maybe some technical issues with the a/c belt spinning properly for an alternator to generate proper voltage and output.  Perhaps not, but this is an important area for you to research.

Of course I cannot be totally sure of your overall level of technical skill, but I can assure you,  jmelton is right.   Dropping in a second alt will be a far, far more arduous process than - and this is a great comparison dude - swapping an air filter.

okay after reading both topis this is what i think im not trying to offend or wiz anybody off this is just my opinion.

you said you already have a red top right? so thats done.

you said you already built a custom box right? so thats done.

you need to decide if your going to mismatch the amps or go with 1.

why do you think you need to upgrade or add a second alt? if want sound quality

the custom box and subs are going in 4 sure so if you decide to add or remove an amp. then its gravy.

im just saying ive seen alot of cars and trucks with more subs and amps than what your working with and with just 2 batts. under the hood. no big three no rewound alt. and no secondary electrical system, and just have their lights dimming a little bit!

my opinion install what you got and go from there. again this is just my opinion!