ELECTRICAL PROBLEMS, please help

last year a had a system in it. not too big, maybe 600 watts..worked fine for a while. then my alternator died and figured it was the system that did it and i sold all my shit. put on a new alternator, bought a optima yellow top. nothing electrical for a while. at xmas i put HIDs in. i heard these draw less current than stock lights but im not sure if thats true or not two weeks ago i was headed to hattiesburg from picayune (about an hour trip) and halfway up there my e-brake light and battery light start flashing at random. "oh shit," i thought. i turned the a/c off and the radio off. it made it just fine. i figured it was a loose wire in the speedo, since i took it off the week before to look at the bulbs) last week i put an electric fan in. wired it thru a relay and a inline fuse using a diagram off a jeep website (got the fan from a buddy who had it in his jeep). the next day on the way to work my truck died. radio starting turning itself off (that's my indicator when its about to break down.) i got someone to jump me off and got to the service center near where i work. they charged the batt. for 2 hours. took it to advance auto for an alt test. battery was good, alt put out 0.0amps according to the guy. which didnt make sense cause even bad ones put out a little bit. went back home and put my belt fan back on and took the electric one out. went to autozone for another alt test. battery still good, alt now putting out 30amps. i drove to hattiesburg with no problems. it was still doing the thing with the ebrake and battery lights tho. but i used the a/c and radio the whole way without it doing anything weird. my speedo also jumps around all the time, if that is in any way related. now my question is, what is causing the problems when i hook up something electric (sound system, electric fan, etc.). what the hell is going on??? i wanna put a system back in my truck, but how can i do it without going thru this bull shit again? will doing the big 3 upgrade help? ive purchased a capacitor for my next system, will this help? the alt belt is TIGHT fyi, 98 frontier, 2.4

Upgrade the big 3, not just because the larger wire but to me it sounds like you have a problem with a wire, im guessing the alternator wire is possibly messed up. just an idea

so the faulty wire could be whats preventing anything extra from working properly? could it just be loose or what. i dont even know where the wire goes or comes from. the connections are tight on the alternator i know that much

If you walked into the shop with those problems the first thing I would say is "lets get rid of the Optima". I don't know why because I personally have never had a problem with them in my own cars but seems like every car with a voltage problem that comes into the shop has one in it. I would check the alternator next and make sure the charge wire and ground wire from the alternator are good. A ground wire from the alternator bracket to the battery is really never a bad idea. As long as your alternator is internally regulated you should run a wire from the positive output straight to the battery, 8awg is probably fine in your situation.  Hope this helps

fablab....will a 3yr warranty battery from advance/autozone/etc be just as good as far as powering accessories? i bought the optima used so i dunno if thats why or what. so youre saying to add another ground wire? so i'll have 4 total? i wanna go ahead and use some thick wire if im gonna go thru the trouble of doing it. the pos. output goes thru shrinkwrap to the battery, ill take it off and see if its a direct connection. what else should i do?

my guess is the battery is burning up alternators.

The alternator is the problem, I had an 03 civic that did the same shit, I would be driving to work about an hour drive and all the lights would turn on and the radio would turn off.  I changed the alternatorwhich was a pain in the ass and it did the same thing.  The new alternator was bad! So now I always make the place check the alternator before I put it on because changing the alternator on that car was a pain!  But I would say it sounds like an alternator problem!

well the alt is only about a year old. i got it from advance auto, and i hear not to get alternators from them. if its bad this will be the 4th one from advance that has gone bad.

does it have a warranty, I know most around here have lifetime warranties if so id give that a shot

what machine did the guy at advance use to check the battery? optima batteries need to be tested on a "gel setting" and most times the employee fails to do so. only reason i ask is because i work at advance and have seen it numerous times.