Why does my interior lights dim Everytime the bass hits ? What cAn I do to prevent that from happening. I used a volt meter to check if it was my alternator getting bad it went from I believe 12-40 which someone told me that it's not my alternator I just need to get another battery because it cant handle my system..I got 2 10's jl audio w3's and a Rockford fosgate punch p450.4 amp.

 

Perhaps a grounding kit is necessary. I installed one on my 07 many years ago, and it brought a lot of life back to the car, windows rolled down and up faster, lights stop dimming...ground tends to get a little weak over time.

Also, if you're using an aftermarket amp for a sub, and that's pulling a lot of juice, it may be the amp doesn't have enough internal capacity. A lot of people go out and add an external capacitor, but it's been my experience that if you have a good quality amp, you don't need an external Cap...I didn't believe it when I was told that before, but discovered that a $200 amp vs a $600 amp you will see a tremendous difference in the quality and life of the amp. Of course price doesn't always mean better, point to be made, a cheap amp, you get what you pay for.

 

Are those 2 ohm or 4 ohm subs?? Are you using that Rockford just to power the subs? If so are you running it in 2-channel bridged mode (claimed 225w RMS/ channel x 2 in bridged mode but I don't buy it) or just using 2 channels in 4-channel mode?

 

I'm sorry I had them installed I should of asked all I know is the amp is a 4 channel that's all....

 

My guess is on the battery. Take your multimeter to the battery and check the voltage. If it's under 10 volts, that could easily cause dimming lights on an aftermarket audio system.

That amp isn't powerful enough to cause dimming on a normal, healthy battery.

 

Add a ground from battery to chassis and replace the factory alt to battery wire with a 2awg .

However these other guys are right that something else is wrong. A 400w amp shouldn't be stressing that electrical system that much.

 

Amps x Volts = Watts

110 amp alt, say 12.6 volts if he's lucky and running on all original, poorly maintained equipment = 1386 watts, subtract 70% for normal vehicle operation = around 970 watts, add 400 watts for the amp, a ****ty 10 year old battery with corrosion on every connection, missing or severed grounds, and a few shorts here and there...

Yeah, his charging system is on it's last legs. Get rid of the stereo or start overhauling your electrical system. Those are your options.

 

overhaul ? Be specific pls and I'm using the stock Bose stereo

 

If a 400w amp is putting over the edge then the system is already shot. Getting rid of a stereo would not help. It would only prolong the inevitable. Guys don't get hung up on watts and electrical drain. An amp rarely puts even 80% of what it's capable. Most of the time its around 20% when listening to music at high levels. So forget the stereo in this situation. It's a symptom not the problem.

User1 is right. Check your wires. Add the ones I told you. It helps even without an extra drain on the system. The voltage at the battery should not drop below 12.5v even with everything running.

 

Im aware of amp efficiency. I was trying to be optimistic for him. The amp still pulls the amperage it needs to make the power. Whats lost as heat varies by amplifier. The system is shot in an old and probably poorly maintained vehicle. There is no simple fix. The car needs work and money put into it.

 

400 watts at 12 volts is approx 33 amps. So when the bass hits, this is the momentary draw on the system. The alternator does not produce maximum output at idle, that happens at around 2K rpm IIRC. so anytime the car is using more electricity than the alternator is producing, the battery has to make up the difference.

In your case, I think you should work on the grounds and all connections. Personally I would run extra, larger gauge wires for the ground and 12 volt wires from the battery to the amplifier. 6 gauge wire is good for 40 amps at 20 feet. Combine this with a larger battery and I think you will have eliminated the problem.