2 power questions

Alright heres my question/problem. I did the Big 3 with 0gauge wire. I upgraded to an optima yellow top battery and my headlights still dim when I have my music turned up. I am running 2 pioneers 12's (not sure of the model) and my tweets/mids are alpine (again the models escape me). The speakers and the subs are both amped off of two seperate amps pulling about 1700 peak. I was told I need a Cap but I wanted to check here first because I heard they were useless.

I am sure my grounds on my Big 3 are good. I have checked and rechecked and I do notice a difference but everything still dims.

My other question isn't really a power question I was just wondering if anyone could tell me where I could find a tutorial on making an amp rack?

Any help is appreciated
~Drew~

Could it be possible you need a better alternator?

Thought I put that in the original post. Its a new alternator but its not a H/O alternator. According to my local stereo shop I shouldn't be pulling that much to need a H/O.

I wonder if this helps. A stiffening capacitor might improve the situation. I have read that they recommend you place the cap on the amp running your bass driver (subwoofer).

According to what I have read, Capacitors function when the power required is greater than the power used. Hence only subwoofers suck enough power to operate the capacitor.

Here is a link that might help: Car Audio Capacitors (http://www.electronixwarehouse.com/car/accessories/capacitors.htm)

I hope this helps, and please come back and tell us how it works after putting up a capacitor? Thanks in advance.

u dont need a cap. what size alt does your car have?

I think this site will help. click_here (http://www.crutchfield.com/S-ZkkZqmbOy9r/learningcenter/car/amplifier_installation_guide.html?page=5)

Please read like the last paragraphs on the page. It does mention that your lights dim because there is not enough power coming from your alternator so it then starts taking power from your battery, and that is why your lights dim. It recommends to upgrade your alternator and it also refers to a capacitor. It's very informative.

I think it only puts out something like 130amps. Which I told the stereo shop but they said I couldn't be pulling that much and wouldn't need an H/O alt. Maybe they just wanted me to buy a cap from them.

I really dont know where to go for a H/O alt, and if I happen to get a cap what kinds are good. I know nothing about them but im guessing the more fareds the better?

130 should be good for around 1300 watts or so maybe even more. unless it is on its way out. and do u have a muti meter?

caps are useless for SPL, on occasion they do help a little with blinking lights. The only thing that matters on cap specs is the ESR, those big 25 farad block caps are worthless because the ESR is so high, so are ones with the voltmeters on the top.

The most important thing is the wiring, especially the connections to battery, fuse holder and amp(s). Just a little bit of extra resistance can effect the power transfer greatly.

I have a multimeter and I checked and rechecked all connections and cleaned them. Everything is getting tons of power I'm guessing it may have to do with my car being an 87. If I have my music on and open my doors the interior lights even dim and my dash (which is digital) also dims.

I'm guessin an H/O alt may be my only way out. I'm pretty sure my alt is not going out but I'll take it out and have autozone check it right after I click reply. :)

They said its fine. Old but fine.

what is your alts voltage reading with your music 3/4 volume? up

walmart/radio shack meters are not sensitive enough to measure the resistance drops you are looking for. $200+ fluke might, with the right probes ...... usually the kind that sensitive are $1000's of dollars.

The equation here is a simple one, known as ohms law. It says V=I*R, so if you are drawing 100 amps and the resistance of the connection is .005 ohms, then the voltage drop is 100*.005 or .5 volt. That's not too bad, now lets add them together - .005 at the the battery, .005 at the input of the fuse, .005 at the output of the fuse, .005 at the amp, .005 at the gnd side of the battery, .005 at the chassis gnd point, .005 at the amp gnd lead and .005 at the amp gnd point. Thats 8 if I counted right, 8 x .005 = .04 ohms total, .04 X 100 = 4 volts. In this simple example with fairly good connections (beyond what any multimeter can measure), a 100 amp current draw would cause the voltage at the amp to sag by 4 volts. This is why clean, tight connections are so critical - even if you can't actually measure them.

Even worse, if one of the connection had say 10 times that resistance, it will heat up badly when playing at full power and will eventually burn up or catch on fire.

This IR drop is also why caps with any kind of ESR are pretty much useless. The cap can only operate betwen the 13.8 - 14.4 volts of the alternator and the 12.5 V setpoint of the battery, so the IR drop can only be 2 V max before the internal resistance of the cap will prevent it from discharging. In a 200 amp system, the max for the ESR can only be .01 ohms for a max 2 volt drop (.01 X 200 = 2 V).

what is your alts voltage reading with your music 3/4 volume? up

Well if i'm doing this right its 13.4.

you really need a meter that will capture the lows or an analog meter with a needle. The voltage will fluctuate some when the bass hits.

Take it to a shop and have them test the alternator. Heck if they say its old then you might as well replace it anyway, stock alternators are not that expensive these days. Or get a H/O alternator if it makes you feel better. Its not going to hurt anything but the wallet.

Well my alt passed all the tests so I guess maybe I do need a H/O alt. I dont want to get another stock alt if I'll go through the same problem. I cleaned all connections again including my Big 3. Nothing changed. If its pulling power from my battery like that could I end up stranded one day with a dead battery? Thats my main concern.

So today I went to ask a shop (a different one from the one i frequent) to ask how much troubleshooting was since it wasn't to much I let them look at it. They checked every connection and said that I prob need a H/O alt because my alt is having a hard time trying to keep up and it would fail soon from being over-worked. So now I'm looking for a H/O alt. Do they all require me to mod my brackets and such, are they easy to install?

try Nathan out

http://www.excessiveamperage.com/

I emailed and asked for a price quote. He offers 200Amp,250,and 300. Any suggestions on how many amps anyone thinks I will need. Taking a wild guess 200 or 250 seems like more than enough.

the more the better if u can afford it. plus with ho alt usally they only give out half of there rated amps at idle.

Nathan can make your set points on the voltage regulator lower so it will have more juice at idle.

yea he did that to mine. it is set at 14.2 i think.

ok, everyone is wrong, dont know but what i did read is wrong, it doesnt matter if you have 25 0g wires running to your amps, cause all you have from the alt is one maybe 10g to the batt, try replacing that with 0g and you'll see a difference. and a cap is not worthless, just not enough to fix the problem on its own. I am a master installer and own a mobile electronics store so you might just get some help from this.

ok, everyone is wrong, dont know but what i did read is wrong, it doesnt matter if you have 25 0g wires running to your amps, cause all you have from the alt is one maybe 10g to the batt, try replacing that with 0g and you'll see a difference. and a cap is not worthless, just not enough to fix the problem on its own. I am a master installer and own a mobile electronics store so you might just get some help from this.

hey smart one, if u read the first post u would have saw that he said he did that already.:wink:

if someone replaced a stock alt with an oversized aftermarket one and just used the 6 Ga (or so) factory wire - they need to be jack slapped. Personally, I don't know anyone (that actually does installs) that would be that stupid. I guess I have picked up a few things over the last 30 years of competing and installing (in car stereo) as a hobby, but I am always open to learning something new.

I got an automatic E-mail from him saying he will write me back tomorrow between 8am to 4pm Central tims. So tomorrow I will know how much my gift to myself is going to cost me. Might have to cancel everyone elses xmas gifts :rofl:

welp he said
"
I can custom build you the following that will be built with all new parts and will bolt on with no modifications :
200 amp $330
250 amp $420
300 amp $510
These prices include shipping and insurance in the U.S. It will also come with an pverdrive pulley installed on it. Let me know if I can help. Thank you,
Nate"

Are these good prices or should I continue looking around?

looks pretty reasonable to me, I have not purchased an HO alternator in more than 10 years - so I'm not really up on the prices.

Well like you guys said if I can afford the best I should get it. Right now I can get the one for $330 but I think I should save up for the $510 one so I wont have to worry about it again. I hope the prices dont change much between now and the next two weeks wen I get paid.

they shouldn't change on the prices. and btw what do u drive so we can try to find others. and i would get atleast the 250 amp one.

O sry I never did post my car and I forgot I took it out of my signature. Its an 87 Oldsmobile 98 Regency Brougham.

I appreciate all of your guys help.