Lights dimming from amp

SPUMONI_RT · Post by **SPUMONI_RT** » Thu Sep 10, 2009 6:39 pm

I just recently upgraded my ICE system, I have a cap and did not have noticeable light dim before the upgrade. Now they dim a lot. So my question is how do I fix this? I have 8 gauge wire, and two amps running off that, which is one wire to the trunk and split there. Only one amp is running through the cap it is 500K micro farad (wal-mart special) so proably 0.5 of a farad. I think it may be just power hungry amps with too little of wire any suggestions will be apprecated. Also what size wire should I run.

BSOD2600 · Post by **BSOD2600** » Thu Sep 10, 2009 7:38 pm

OT: 500K micro farad (uF) is the same as a 0.5 farad

roundeye · Post by **roundeye** » Thu Sep 10, 2009 9:35 pm

umm, so, you added amps, and now it's dimming? cap should be enough; i'm running a jl 500x1 for sub, and a 75x4 for fronts/ mid bass, with a .5f cap, and minimal dimming only with EXTREME bass. logged it one day, and my max draw was 54 amps, with an average of 15. i did notice, after adding a 4 gauge ground to the alt., my peak voltage dropped from 14.3, to 14.0, but remained much more consistent. also, if your power cable to the cap is too small, the cap wont do its job. i'd try at least a 4 gauge cable, and an additional alt. ground.

SPUMONI_RT · Post by **SPUMONI_RT** » Thu Sep 10, 2009 10:53 pm

No I did not add amps. I simply bought a new amp and sub and it isn't a HUGE upgrade either. All the wire is 8 awg. I have done the "ground mod" so the alternator is grounded better I guess, also I figured that 500K micro farad was half a farad. Thanks for the comfirmation though. I think it is just small wire sucking juice and it cannot get enough so it pulls it from else where that is my guess. So correct me if i'm wrong.

roundeye · Post by **roundeye** » Thu Sep 10, 2009 11:16 pm

it's not that the smaller wire uses any power, but having a large capacitor with a small gauge wire, which acts as a resistor, the cap can't "refill" itself quickly enough. may be that your new amp is drawing just past the current your cable can supply. have you checked your voltage drop across the power wire? if it's more than a few 10th's of a volt, you need a bigger cable.

magicmike · Post by **magicmike** » Fri Sep 11, 2009 4:26 am

How do you have the cap wired? What is the total fuse count for both amps? Meaning, one amp has two 25 amp blade fuses and the other has one 30 amp fuse for a total max draw of 80 amps. Whats your max draw?

SPUMONI_RT · Post by **SPUMONI_RT** » Fri Sep 11, 2009 6:26 pm

I'll post a picture from paint in a moment. One amp has two 25A's and my new rockford doesn't have any that I can see, unless they are inside or something, but that would not make sense. Also the distribution block has two fuses one 40 and one 30. ( They were out of more 30's) so max draw is either 50 amps or 120 amps idk you tell me. But I'm going to look into it for you, thanks for the help.

SPUMONI_RT · Post by **SPUMONI_RT** » Fri Sep 11, 2009 6:27 pm

The cap is after the distribution block. It is only goning to the sub's amp not the other one.

SPUMONI_RT · Post by **SPUMONI_RT** » Fri Sep 11, 2009 8:41 pm

http://s130.photobucket.com/albums/p263 ... =power.jpg

hopefully this works

magicmike · Post by **magicmike** » Fri Sep 11, 2009 9:48 pm

ok, well I've blown 40 amp fuses pushing 1 ohm mono on my soundstreams before so if your rockford has not blown that 40 amp in the fuse holder I'd say your ok there. Sometimes there is a plastic plug in the bottom of the amp that you remove and the blade style fuses are under there.

You don't show where your grounds are. They are just as important as the power wires. I'm not sure how good this is wired up with the cap only getting juice from the 40 amp fuse. Fuses are very restrictive.

At this point I don't think the cap is going to save on your dimming lights. A stock alt in our car is good for 60-65 amps at best. When drawing over 60 amps for a system I've had good luck with adding another battery and two 1 farad caps. The second battery setup holds up well to the system and the alternator "trickle" charges the second battery just fine.

brand · Post by **brand** » Fri Sep 11, 2009 10:15 pm

Did you ever fix your ground points? http://bbs.legacycentral.org/viewtopic.php?t=40904

SPUMONI_RT · Post by **SPUMONI_RT** » Sat Sep 12, 2009 12:39 am

Thanks Mike your knowledge is amazing.

The grounds are on the trunk floor. I ran them (3) under the carpet under the plastic where the spare tire is. Right where it slopes down to the spare. I sanded the paint and used a piece of metal with (short) self-tappers on either side to hold it down. They are as short as possible, the longest one is under two feet.
If anything is unclear I could possibly get some pics of what you want to see.

Should I put the cap before the fuses?
Do I need a cap for each amp? Why?
Should I put bigger fuses in the block?
Sorry for all the questions.

I'm going to look into getting another battery in the trunk. If you could help me by telling me what I need that would be great.

Thanks a lot

SPUMONI_RT · Post by **SPUMONI_RT** » Sat Sep 12, 2009 12:42 am

brand wrote:Did you ever fix your ground points? http://bbs.legacycentral.org/viewtopic.php?t=40904

No, but I will, I just started school for auto collision repair and refinishing so I don't have as much time on my hands as when I was laid off.

magicmike · Post by **magicmike** » Sat Sep 12, 2009 2:39 am

ok, no need for the kind compliments but I appreciate them.

I would start by really examining that rockford amp. At a minimum can you tell me what the model is so I can google it and get some specs?

Once we know what the draw is on the sub amp we can see if the awg wire you have running from the front is big enough.

Do you have that wire fused at the battery? If so what size fuse?

I see you only have 8 awg wire running from the battery to the fuse holder. I think that is your biggest restriction in the system. I know 4 awg is expensive but its worth is and you never have to upgrade from that.

I'd reccomend getting some 4 awg and running that back to the cap. from the cap you can run 1 wire to each amp, keep an 8 awg for the small amp and if you can fit 4 awg into the rockford do so. Ground the cap, and both amps to the same spot. Be SURE to use the same awg ground wire for everything!!!

If the amps have fuses in them you don't need to fuse externally.

you NEED to fuse at the connection at the battery. and the fuse size is not dependant on your amps but dependant on your car's electrical system so you don't damage it. So 60 is good.

Post by **Legacy777** » Sat Sep 12, 2009 4:54 am

I agree with Mike. You really should run 4 gauge wire to the distribution block. That or run two separate 8 gauge feeds for each amp.

Like Mike said, run a power lead from the cap to each amp.

From your description above on your groun, I'd suggest using something similar to what I did here. I wouldn't recommend grounding to sheet metal.

SPUMONI_RT · Post by **SPUMONI_RT** » Sat Sep 12, 2009 6:44 pm

Rockford Fosgate P300-1 no need to research I already did.

(No on-board fuses — when installing multiple amps in a system, an additional 60-amp in-line fuse between the distribution block and the amplifier is recommended.) Right from Crutchfield. So I assume that the cap replace the distritubtion block. So I can just get rid of that, correct? Why should I use a smaller awg wire for the smaller amp?

I do not have a fuse after the battery because I dumb and never wanted to get one, but I will now.

I thought about putting the grounds there. I was worried about rubbing from the seats. And I would have to make my grounds longer to reach there. I was told to keep grounds short as possible.

So i'm going to get an inline 60amp fuse next to the battery run 4 awg back to the cap split it off the cap to each amp. Upgrade all the grounds to 4 awg also. Correct?

magicmike · Post by **magicmike** » Sat Sep 12, 2009 8:09 pm

you're on the right track. The oinly reason I say keep 8 awg on your smaller amp is because it does not seem to need 4 awg and probably isn't worth the cost of the extra 4 awg terminals, not to mention you probably can't fit 4 awg into the amp any way. Good luck

SPUMONI_RT · Post by **SPUMONI_RT** » Sun Sep 13, 2009 1:11 am

Ok thank you both for your help.

Legacy777 what is that bar above the other bar with the ground?

Post by **Legacy777** » Sun Sep 13, 2009 2:31 am

I put that bar there to mount my amp

I've got the amp mounted to a piece of MDF wood and then ran screws into the wood to hold it. I needed another bar there to properly secure it.

http://www.surrealmirage.com/subaru/ima ... acitor.jpg

SPUMONI_RT · Post by **SPUMONI_RT** » Sun Sep 13, 2009 5:04 pm

Cool, I thought is was some sort of body stiffening bar or something.

SPUMONI_RT · Post by **SPUMONI_RT** » Sun Sep 13, 2009 6:00 pm

LAST QUESTIONS

Recommened place to buy wire from?

Length of RCA cable?

Is Scosche any good?

Do I need a fuse in between the cap and the "fuseless" Rockford amp, or is the fuse after the battery enough?

Post by **Legacy777** » Mon Sep 14, 2009 6:13 pm

No you don't need a fuse between with the cap & amp. Or at least I don't have a fuse between my amp & cap.

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Lights dimming from amp

Lights dimming from amp