I think my stereo is causing electrical problems in my truck. It has been installed for a few months now, and has been working great. But now when my subwoofers hit the battery gauge is really jumping around. Finally today while listening to some bass heavy music, the gauge went up so high my check gauges light came on. It doesnt jump up when I am at an idle, but when my rpm's get above about 1500 it jumps up to the red. It still has the stock battery so i thought it might need to be replaced' but why would the voltage go up? Could this be a voltage regulator? I will post this question in the elecrical section too. Thanks for any help!!

How big is the amp? You may need a cap.

a big enough cap might help if the rest of the charging system were good, but not if something is already going bad. The amp is an alpine, model number slips my mind, but it is last years model and it puts out 800 watts rms.

Try a local auto parts store, they may have a testing station they can check your battery and alternator while in the car. If not, you can always take them out and have them checked. If you want to, you can test them yourself if you have a meter.

i know how to check the battery, how do i check the alternator/voltage regulator?

You can check the battery with the truck off, and then with it running and see what the difference is. Also have someone rev the truck up and see how high the numbers go.
The alternator should have a post on the back that you put the positive lead on with the ground on the battery or another ground. This reading should be the alternator output. Not sure what the number should be, prob around 14 or so. I would think that the alternator is internally regulated as most are these days.

it could be your alternator, usually the voltage goes down and it's normal but going up it's not, you might have a faulty voltage regulator, 440 Sixpack is the one that can answer that for you, send him a PM

seem like you need a bigger alt