2001 civic ex voltage problems

[bmk6795]

Ok guys so ive got a 2001 civic ex 5 speed coupe and im having some very weird electrical issues. I have about 1300 watts of stereo equipment on my stock alt and battery, i know this is very sub par. I have the big 3 done, which is 0 gauge wire from alt to battery, battery ground, and engine block ground. When i drive around sometimes the car drives around at 12.5 volts give or take .2 volts or so. At first i thought it was the equipment so i took it out and it still does it. A bolt had come out of the alt which made the belt loose so i fixed that problem last night and the problem still persists. Ive tried a different battery that is known to be good and problem still persisted. All grounds that i have made with the 0 gauge wire and for the amps are good, ive tested each one. I went to all 3 major parts stores, orielys, advanced, and auto zone, they all said the alt and battery checked out ok. If the alt checks out ok then what could be the problem? Ive tried everything, even undoing the big 3 and rehooking up the tiny ass stock wires.

When i drive on the interstate the problem does not occur the car drives at 14.4 volts as long as im 3k + rpms. After getting off the interstate or slowing down to ~50 the voltage drops. The voltage also drops whenever i hit the gas driving around town, if i leave the car in gear and let off the gas the voltage goes back up to 14.4, but as soon as i accelerate the voltage drops. The problem doesnt occur every single time i drive but it does happen often.

Some say it could be the pcm but why doesnt it do it constantly if its the pcm?

Any ideas or insight would be great.

 

[AlaskaB16]

I bet you've done a number on your alternator. Get one that can handle what you're trying to do.

 

[bmk6795]

I bet you've done a number on your alternator. Get one that can handle what you're trying to do.

Yeah thats the last thing i could think that it'd be. A guy on the car audio site i look at said that he had the same problem and the internal regulator was fried. But yeah high output alt is next on my list to get, they are just so damn expensive, lol.