To Cap or not to Cap

[rbkchamp]

K, so heres the deal, i just installed an old 300 watt (max) kenwood amp with a kenwood 12. My lights are dimming a little bit when it hits, and i wanted to know how you guys feel about a cap. I have a .5 farad that i used in my old car, i didn't think i had to use one for this install. I have a 2004 elantra with stock batery and alternator. i wouldn't think the lights would dim but they do so how bout you guys chime in and give your opinions.... and my other question would be would a cap significantly shorten my alternator life? thanks for your time.

[southpawboston]

a cap will not shorten your alternator life. it will increase the life of your whole electrical system.

i am surprised that your lights are dimming with a 300W max amp. i am running 480W (RMS) and have absolutely no dimming. but if you're having the dimming on hard hits, then i would suggest the cap.

[jrod13]

that is odd that yours is dimming i am pushing a larger amp as well and am not dimming either... cap would do you good

[jjos1]

I found that installing a ground kit helped alot with diming

[getfuzzd]

Use a cap, it helps hit harder and longer, with no more dimming.

[cclngthr]

I have a 820 watt amp with very little dimming with stock components. Sounds like your electrical system is not up to spec.

[Atomic]

Use the Cap. My Elantra GT was the worst with dimming lights out of all my past cars. I'm now pushing close to 1000w, I use a 1 farad cap on my system, which makes a night and day difference, as well as getting an Optima battery. Go to your dealer and have them check your alternator. On one of my past cars I found that there are 3 (resistors?/capacitors?) in the alternator, which I was blowing one at a time because I wasn't using a cap. This lead to dimming all lights with any draw on my car, like driving at night and turning on the a/c. Also my battery wouldn't charge properly.

[Mil]

As your amp is 300watts peak, i suppose that you don't wanna try spl competitions, so you could use your cap, it helps with sound quality and it gives some help to your alternator's life.
Before you install it, i would upgrade the ground wire from the battery, and check to be sure that the ground of your amp is good too. Some people use to small wires or forget to connect the ground wire on a bare metal surface.
Paint between your ground connection and the body can cause a little restriction to the current flow, but that restriction is enough to be the cause of your dimming problem. ;)

[2loud2k2xd]

deffinately use a cap. the golden rule is 1 farad to every 1000 watts. this should help with dimming. also, as stated above, install a ground kit.

[jpjr]

I would upgrade the stock ground wires first. If you still have dimming, a Cap will probably fix it. But if your grounding system cant flow the extra power, then no matter how many caps you add, you will still have dimming.

[cclngthr]

JPJR, I particularly don't like the way Hyundai grounds the car with a flimsy looking connection below the battery. I have an extra ground wire from the battery to the drivers side strut tower, in addition to the ones I have added on the transmission and engine. If I power my amp up all the way, I do see a slight dimming when everything is on (my amp has the same RMS rating as Southpaws amp).

I also would have the alternator tested as well. It should be pushing 14.5 volts at high idle with everything on.

[southpawboston]

i agree with the above; i don't think the stock battery ground is sufficient. i supplemented mine with another short 4-gauge wire bolted directly to the strut tower.

[sed]

why not just cap to be safe though? With a cap you are taking away some of the drain on the charging system. to me, that is enough reason to cap.

shawn :)

[jpjr]

I agree a cap is a good idea, but no amount of caps can fix a bad or weak ground.

[2loud2k2xd]

check out the set-up in my ride. major system install. dual battery, ect. sometimes i still get minimal light dimming. granted, i still use stock alternator. peace

[cclngthr]

The only way not to get light dimming is to isolate the amp on a second battery that is completely separated electrically from the main electrical system. Doing this isn't necessary. All you need to do is redo the grounding system.

[jjos1]

now this maybe off topic but I noticed when I put my grounding kit on, I picked up some ground noise that my deck did not have before ? If that makes sense

[cclngthr]

Where do you have your audio cables run? If they are near any power leads, you will get some noise. A filter might be necessary to avoid the static if that isn't the case.