Here is the story. I have a 02 Z28, been running the same setup since 2002. A couple weeks ago I put a cd in, drove about a mile with the volume up about 3/4 and fried both my JL audio 10w0's and even shattered the 60amp fuse under the hood. I started using my other car to go to work and didn't drive the Z28 for about a week, when I did I noticed it didn't start like it normally does, was slow to start and at work I turned the key and nothing. Lights came on etc, so I took it out of Park and put it back in park and started fine. Then random times it would not start when I turned the key or even try to start, would turn it off and try again and starts fine.

So, I went to a battery place and they tested me alternator and battery. They said the Alternator was good and then said my battery when the stereo was on dropped down to 10 volts. So I had them put in the biggest Optima Red Top they had, is 1000/800 cca(model SC34U).

I bought 2 Memphis audio PR series 10 inch dvc subs and wired them to 4ohm and connected them to the amp in 4ohm mono load(same setup as the JL audio's I fried). I went out and replaced the 60 amp fuse, checked the body ground coming off the battery and all looked good, zero corrosion and all tight.

When I listened to the Memphis subs, I noticed my bass control **** I normally left at almost all the way up, now needed to be about 1/4 way up and I had about the same bass as with the JL's. Sitting with the car running the voltage still drops, not so bad when driving, but it never happened with the JL's in the car.

With the odd starting and voltage drops even with a new battery, It seems to me it would be a ground. Where should I look for the grounds on the car and would a larger ground help possibly? I'm not sure what to look for, seems like everything happened at once, battery became weak, car started acting up starting and now still voltage drops way more than before. Any help or info would be appreciated. Thanks in advance and Sorry for the long post.

Audio Setup:
Kenwood mp922, stock monsoon system otherwise except for far rear 4 inch.
MTX old school 2150x amp(425 watts rms)
2 farad capacitor
2 dvc memphis audio PR 10 inch subs.
Pretty sure it had 4 gauge power and 2 guage ground wires.

 

Start off making sure the ground posts you've
got are all clean and tight.

If the battery voltage -at the posts- drops to
10V then that has nothing to do with grounds,
it has to do with drawing too much current or
having a dead cell.

Some electronics react badly to undervoltage.
May draw excess current trying to make the
set power with less voltage. Or just freak out
trying.

 

I may have figured out my problem with the voltage drops, the starting problem may be all different. This is my first time ever having DVC subs, so I asked my wife to look on the site I had on the pc and let me know which wires to connect to what. She said connect the + and - together on 1 side of each sub, then run the + on the oposite side of each and - to the + and - on the amp to see a 4 ohm load. So I think it totally left out 1 voice coil on each sub and was running single voice coil on the dvc subs at 2 ohm. That would explain the voltage drops, because the amp is not stable to 2 ohms mono, would be putting out about 700 watts rms, and would explain the bass **** at 1/4 volume still being as loud as previous setup. Lucky when I listened to it, I only had it on a few minutes and never went up with the volume when I seen the voltage drops. Could have ruined my new subs running each on 1 voice coil and fried my amp .

 

i had a problem with dropping voltage, it had just suddenly started half a year after i installed my system. every time the amps turned on, the capacitors would go from reading 13+ volts all the way down to 10-9 volts. i disconnected one amp and it stopped, disconnected the other amp and that didnt affect anything. turns out i had an amp grounded to the same spot as the caps and i guess over time it quit, because after the problem started i noticed either the caps or the amp had to be on. switched the ground, and everything is fine. the other amp was grounde on the other side of the car which is why it caused no problems.

 

Problem fixed now, was wired to a 2ohm load(amp is not 2ohm mono stable). 0 voltage drop now even at idle with the bass pounding, so the Optima red top is helping. Is better now than before and the Memphis Audio subs sound excellent. I'm really happy with the SQ of the PR 10's, deep, tight bass in the millhouse box without any muddy sound. Even with the gains way down on the MTX amp it hits harder than the JL audio 10w0's.