voltage drop

[rb25crazy]

so, the other day i was standing at a stand still i turned my steering wheel full lock to turn to back out, i saw my voltage go from 13.2 volts drop down to 9volt and then just cut off, then my stereo just cut off and then came back on immediately. normally my voltage is around 13.2 volts even with lights, fogs, stereo, defrost, power windows being pushed sometimes it dip to 12.9 or 12.8volts. the following day i turn on the car it initially shows up at 14 volts which is normal from what i've seen. When i start to drive off and have everything on. it goes down to 12 volts or 12.3 volts now. but, then goes back to 13.2 volts at times. this happened for the first time so, I've been looking at the voltage meter more often now. my question is what could be causing this? possible "dying alternator, or near the end of its life" my car has 1997, 160k, ka24de, stock and never changed alternator from my knowledge. ever since i installed my amp and speakers I can hear the alternator whine. Not sure, if that is because of the way i routed my power cable. thanks for the input

[HPKMotorsports3]

alternator is dying... take it out and double check at autozone or strauss... if its not that most likely is battery

[airforceone451]

You'll hear alternator whine because your amplifier is pretty sensitive. You can get rid of it with some filters. But see if you can source a good, working alternator to see if it is indeed your alternator which it kind of sounds like.

[510-SR20DET]

your alternator is dying. You should change it asap or you will get stranded on the road like i did. It happened to me.

[NINJASPY]

check grounds. get a capacitor for the amp. make sure power steering is topped off(uses more power when low)
stock alternator is 90amps or so? which is roughly 900watts.
Car needs atleast 50-60 to run ok. so that leaves about ~300watts for your system. even then you don't want to load the alternator at 100%, at idle it will not make enough power.

rebuild alt to higher amperage, or just get a new one already built for high amps.
noise filter does nothing except get rid of the noise... but alternator is still being hurt from all the drain.

voltage should be at 13.8-14.4 when car is on, which means healthy alt/batt (I am at 13.6-13.8 with 100watt rms amp)
12.3-13.2 is too low, anything in the 12's is too low when the car is on.
fix it before the alternator takes out the battery... they take each other out.
run car with amps disconnected, see if you get good voltage.