voltage problems

Currently installed in my 1994 Acura Integra is an Eclipse CD8445, Eclipse 6-1/2 separates in front, Eclipse 6 x 9 4-way in rear, one Rockford Fosgate T1 12" sub, 2 Rockford Fosgate amps (T5002, T8004), Rockford Fosgate CPCC1 50-farad cap, Kinetik HC1400 battery under the hood, and 160-amp high output alternator.  My system is about 4 years old (excluding the batteries, which is the 3rd one) and was installed by an audio shop.  I noticed that my battery light goes on while I was driving.  So, just recently, I checked out the battery voltage using the digital meter on my charger.  It showed 14.4 when I started the car, before putting a load.  I turned on everything except the stereo, and it showed 13.9.  Then, I turned on the stereo, and it showed 13.3.  When I put it into drive, it varied from 13.6 to 12.0.  I've had someone told me that the cap might be going bad and I should replace it with a second battery.  Is it the cap going bad or the alternator weak or bad? 

Get the alternator tested.Support the12volt.com

Had a similar problem with a Civic, check the belt and make sure it is not loose.  At speed it was slipping and not squealing at all.Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB

I had the alternator tested and checked today by a shop that specialize in auto electric.  They said that the alternator, connection, and belts are fine.  I had them even replace the voltage regulator.  I don't see the battery light on the dash while I was driving, but when I got home, before I turned off my car, I hooked up my charger to the battery and the digital meter on the charger says the voltage was between 13.8 and 13.6 and with everything on.  But, I checked the meter that is on the cap, and it said anywhere between 13.0 to 12.2.  Even when I turned everything off (including the engine), the meter on the cap said between 11.9 to 11.5.  Is this problem tied in with the cap?  Should I replace it? 

You shouldn't rely on the read out on your cap. Use a DMM and check the voltage, that would be a more precise reading.

Test and see if the cap is shorting out by removing it from your system.Support the12volt.com