So first let me start by explaining my setup, I have 2 12" MB Quart subs inside a ported box (ported through stock sub opening in rear deck) with a Sundown Audio 1500 watt mono amp. This is wired to my stock head unit (non nak or ML). I have not upgraded anything else.

Ok so a couple months ago I started noticing that the bass would lower significantly or just completely cut-out every once in a while without notice or me lowering it. I can control the bass through the HU or the seperate bass control ****. Now when it would go out completely i could turn up the volume or raise the bass on the HU or control **** all the way up and it would make no difference. I started thinking maybe from all the bass and vibration a wire had come loose or something . I haven't had a chance to take it into the shop because of my busy work schedule so I just rode it out like this enjoying the bass whenever it felt like coming back. One day I was vacuuming out the front of the car and turned off the car but left the keys in the ignition on the acc position. Literally within 5 minutes I tried to start the car but it was dead, completely .

So i jumped the car and decided it must be the battery so I went and dropped a little over $200 on an Optima Yellow Top Battery (D34) and had it installed and my old battery removed. It was absolute heaven, music to my ears, the bass was back and better than ever. It never faultered until about a week later , now I'm back at square one, bass goes out when it feels like it and will return unannounced. What do you guys think is the issue here? Bad battery again (doubtful)?? Bad Alternator (maybe I just need a bigger one)? Maybe I need a capacitor? I have no clue guys, someone on here pleeeeeaaaaaasssssse chime in and give me your opinion or your past experience with this because it's driving me insane not being able to listen to my music how I'd like ...

 

Here's a link to a thread with pics of my trunk setup from the outside at least ... post #67

https://www.clublexus.com/forums/gs-...ok-like-5.html

 

i would get a voltmeter!!!! i would see if there is any voltage fluctuation in the system!!!! If your alternator is working right it should sit around 13ish volts. If not when your bumping it should drop dramatically. are you running a cap or extra battery. when i had the sundown amp i had an extra dry cell battery just incase. could be your hi lo going bad. i would get a y cable from radio shack with a mp3 player and run it straight into the sundown. just a few ways to trouble shot the problem. if you dont have a voltmeter i would go to kragen or something to get a test run. usually they are for free and what not.

 

Something's wrong here. It shouldn't have killed the battery in 5 minutes, especially if the radio wasn't turned on. Idle current should be very, very low. Where are you getting the signal to turn the amp on? The battery may have been on it's last leg, but this isn't the source of your problem in total.

Good choice.

I think the problem is either an intermittent connection to where you are getting the signal (unlikely), or that your car isn't capable of supplying the amp properly (very likely). Did you upgrade the ground cable under the hood? 1500 watts is quite a bit of power, and should be drawing down nearly 110 amps on a full hit. That's going to require at least 2 ga wire to be safe, but I think there is a bigger problem looming.

If the car is running okay, it is likely a voltage problem from the alternator since you're in a GS and your alternator is 100A. Even though the amp doesn't draw the 110A all the time, you are exceeding the capabilities of it on a regular basis. Depending on how often you play the music loud, you could kill another battery in short order. Adding an additional battery or capacitor isn't going to solve the problem of the alternator not being able to keep up since they don't create power. Once the voltage gets up to where the amp can operate, it comes back on. You were cycling the battery before, and it finally crapped out. If you continue this cycle, you're probably going to have another deceased battery on your hands, albeit taking a bit of time since the Optima has a better refresh rate than a typical lead acid battery.

I second the idea of a voltmeter, but I'm definitely not on the side of the LOC being the source of the problem. Good suggestions on starting the troubleshooting, though.

Big Mack

 

I'm honestly not too great with audio and wires and all that stuff so I have no idea where the signal is coming from to turn the amp on, I had this all done at a shop.

As far as the cable goes I'll post a pic of under my hood, but there is a 0 ga wire (monster) i believe connected (or grounded) to the positive battery terminal connector. That was placed there by the shop.

Ok so I'm guessing the best way to solve the problem then would be getting a bigger alternator? a higher capacity one? If so where can I buy a good one which won't leave me broke ...

I hope no one flames me for this one but what is a voltmeter and where can I get one? I'm guessing it's something that measures voltage but what does it look like and how does it work? Where would I connect it?



Sorry for all the question but so far thanks for the help and suggestions, I really would like to fix this as quick as possible ...

 

Here are the pics of my engine bay, the wire used to be clear but it's been in there almost two years so I guess that's what extreme heat does to you !!




**BTW this picture was taken a while back while I still had my old battery in**

 

That's not a ground wire. The ground wire should go to the negative terminal. The positive wire goes to the positive cable (shocking, I know). If there is no large cable going from the negative terminal to the frame, this could be a part of your problem.

It may be the solution. Not sure where you'd get a high output alternator for cheap. I know a lot of people swear by Iraggi, but that's for you to research. I suggest the XXX thread in the GS forum for pricing information. (do a search here)

Okay, if you're not sure where you'd use a voltmeter, I'm very concerned with you attempting to get this fixed by yourself. You paid good money to a shop to put the system together. Time for them to earn it with their customer service and follow through.

Big Mack

 

Ok so I need to have a cable from the negative battery terminal grounded to the frame? any specific kind?

Well honestly I'm not looking for cheap since I know quality pieces cost money but I don't want to spend $500 you know? I'm hoping something between the range of $200 - $300 ...

Lol I'm sorry i should have been clear before, I WILL NOT be attempting to fix anything here by myself, I'm not trying to blow my car up (exaggeration) . I will definitely be taking the car to the shop to have them fix everything but I'd like to know what the issue is and know everything I need so I can go buy it all and take it with me to the shop. I also would like to know what to tell them so they already know what they're looking for and can solve the problem quick and easy in a single day. But if you explain a voltmeter to me I'm pretty sure I can figure how to measure the volts my car is running ...

 

Yes, the wire kind. It should be the same gauge as the positive, and it should (ideally) be as short as possible to a thick piece of frame or the body of the car. The factory location will work, provided the bolt is large enough to secure the cable.

I didn't mean cheap in quality. I meant cheap in the overall cost. You may well be able to find one for less than $300. Just be sure you get a warranty, as HO alts are known to have shorter lifespans than factory.

And thank GOD for that!! :P

Check to see if they upgraded the ground already. If not, that's a starting point. They should be able to handle installing an alternator for you if they're a professional shop. That's really the extent of it at this point.

For a voltmeter, you simply plug the probes in to the positive and negative terminals on the amp. When it cuts off, if the voltage is down significantly, this is the problem. If it's still over 13 volts when it cuts off, it could be something different. I don't recommend even bothering with this, however, if the ground hasn't been sufficiently upgraded, so that's your first step.

Big Mack

 

Ok cool thanks for the help, I'll start looking for good alternators tonight but won't be able to get my car into the shop until Wednesday the earliest but I'll kepp you posted.

Meanwhile, if anybody else has any suggestions feel free to jump in