surge after battery, alternator swap

Hi, I just swapped out my Optima battery and replaced my alternator. Now I have a power surge in my electrical system which makes all of my lights dim and get brighter constantly. I brought the alternator back and told them that I would like a replacement because of what was happening, but they tested it and said it was ok. I explained my situation: I had a big stereo system hooked up an extra battery and capacitor, but they told me that the battery was too strong, and to get a bigger alternator.

Now I have had the old Optima battery for over a year with the capacitor and no problems. I know that I fried the last alternator with the stereo, and just wanted to replace the stock alternator until I could save up for a custom one, But does anyone think that the NEW alternator is bad, or have any idea what is going on? The voltage constantly jumps around from 13.8V to somtimes 15.5V! >:(

I don't want to fry anything! As of now, I disconnected the stereo, capacitor, and extra battery, and no change...

What kind of vehicle? Is your voltage regulator inside the alternator or is it external? You can take the car to most chain auto parts stores and they will do a free test of your alternator/battery. At least that way you get an unbiased opinion.

The battery is too strong? What kind of crap is that? Make them test the alternator IN THE CAR. Bench testing won't tell you very much, bench testing will almost ALWAYS be good or bad, with rarely any indication as to a "halfway" indication.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

voltage regulator.

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1999 Toyota Camry
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Pioneer DEH-P3700MP
Lightning Audio Strike S4.15.VC2
Lightning Audio Strike S4.500.1
Majestic 6.5"

Yes it was the voltage regulator on the alternator. Thank you for your help. I swapped out the alternator for a new one and it worked perfectly!