Voltage drops at idle when both compressors are on.

Hey i have a 99 chevy xtreme. I just installed the bag setup and everything. But now when the truck sits at idle with both comps running the volts meter takes a dive..
Could this be just from the alternator not turning out enough juice? it runs fine with only one comp on but not two. just wondering if anyone has run into this problem and what a solution could be. I dunno why but running a capacitor for these things keeps popping into my mind. has anyone tried that??  

what kind of compressors are they? what kind of power wire you got ran to them?

i run 4g from battery to a fuse then back to where comps are to a distribution block thats fused so 4g in to 2 8g out and also run a relay for each comp. ive never had an issue with voltage drop when comps kick on thats noticeable so it could be your alternator is going bad.  

does it "spike" down, or stay down? This is a standard problem (with my S10 at least haha).
Immediate solution - don't run em at idle haha.  

They are both viair I dunno what model # tho, I have them on separate relays and and fuses also the wire is 10g  

It doesn't spike it stays down  

I'd be careful about that... what about when they're on and you're driving?  

either battery isnt recharging properly or voltage regulator is going bad on the ALT  

or maybe everything is fine, it's just too much at once  

if you put your foot in it and bring the rpms up the voltage goes back up.  

sounds like an alt. issue  

do you think id be ok with a new stock alternator or should i go with a high output  

stock should be fine i never had issue unless you run a huge stereo system,  

only extras i have running off the battery is the 2 comps and a small amp for a 10" sub. but the subs not even hooked up yet so the comps are the only load. i dont even want to guess how bad the drain will be if i hook that up.  

high output didn't do much for me (that I could notice), except require a different belt size and more money. I've had high output and stock alternators go bad. I'd replace it if and when it goes bad, and until then not run the compressors at idle. Has it been replaced before?  

I'm beginning to think the stocker is just on its way out i just talked to the previous owner and he said he never touched it. im almost thinking its original. but im gunna take it out and have it bench tested. my friend ran 2 comps and his volt meter only dropped from 14 to 12. i guess i just gotta try a few diff things and find out