I'm at my wits end trying to figure this problem. I don't know it's my amp, battery, or alternator.

I have one Kicker sub amp and one Alpine 4 channel amp. The problem lies with the 4 channel amp, it keeps turning on and off. It only happens randomly. I have checked all connections and they are tight. I checked all fuses and they are good. I also have relocated the ground for the 4 channel amp but the problem still continues. The gains are not maxed at all on both amps.

I have checked the voltages multiple times and there are the results :

All measurements are at car idle.

Both amps on : 13.79 volts - 13.81 volts

Both amps on and AC running : 13.79 volts

Both amps on, AC running, and rear window defroster on : 13.69 volts

Both amps on, AC running, rear window defroster on, and wipers running : 13.69 volts

Both amps on, AC running, rear window defroster on, wipers running, and headlights on : 12.32 volts

There's another wrinkle in my problem. When the 4 channel amp is turning on & off, the voltage at the battery and at the 4 channel amp would fluctuate between 11.50 volts and 12.75 volts. The sub amp is always on regardless of the 4 channel amp problem.

When the 4 channel amp finally turn on, stay on, and have sound output, the battery voltage would stay at a constant 14.17 volts.

Is this a sign of my battery about to die ? Or signs of an alternator about to die ? Faulty voltage regulator ? 4 channel amp about to die ?

I have gone to numerous Auto Zone and O'Reilly's to have my electrical system checked out and all of them said that my charging system is okay. But I would like to have your input.

If it's the alternator, is it advisable to get a high output alternator ? And if I do get a high output alternator, do I need to up the fusible link amp rating ?

BTW, these two amps are installed on my 300ZX with a factory 80 amp alternator.

Any help would be greatly appreciated....Thanks !

your alt size is small..

What is required fuse for kicker and alpine amp?

Sounds like low voltage is shutting off the alpine amp.

Also, sounds like u need a battery in the back because relying on the frame of the car as a ground has a pretty good voltage drop from front to rear as what you are experiencing.