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do i need a h.o alternator?


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dustinz_03 
Member - Posts: 1
Member spacespace
Joined: June 24, 2010
Location: Florida, United States
Posted: June 24, 2010 at 12:17 PM / IP Logged  

Ok, here goes...

I'm running a 12w7 with a JL 1000/1 and a 10w7 with a 500/1, BOTH off of a 5 farad cap.  Way I understand it is 1 farad for 1000 watts, and you cant go wrong with more capacitance... So my 5 farads should be plenty.  I also understand that caps are just bandaids for power spikes and also helps by discharging faster than the battery.  Also helps that the cap is as close to the amps terminals as possible.  My question is what I should do next because I don't think I'm getting enough power to my amps.  When I had the 12w7 with the 1000/1 hooked up to the cap alone... hit pretty hard.  BUT when I added the 500/1 with my 10w7 my dash lights dim a little bit now and it doesn't really hit harder.  Also my 500/1 cut out once from pushing it too hard.  I'm running the right wiring load on my amps, and my power wire/ ground looks like this.. 4ga power to the cap.  4ga power from cap to amps.  4ga ground from cap to chassis. 4ga ground from amps to cap.  What I want to know is do I need to do the big 3, dry cell, or H.O. alternator???  Am I drawing enough current to need the alternator or do i just need to do the big 3 and a dry cell?   maybe just a drycell?

any help would be awesome

12w7 with JL 1000/1
10w7 with JL 500/1
Power Acoustic 5 Farad Cap
I have a 10 and 12 because you don't see that combo very often
diskdrivex 
Member - Posts: 19
Member spacespace
Joined: October 22, 2007
Location: Indiana, United States
Posted: June 24, 2010 at 3:09 PM / IP Logged  
im guessing they dont seem as loud because they are mismatched, you migh try watching a topic i just started im sure some of the responses there if not my original post will be helpful
https://www.the12volt.com/installbay/forum_posts.asp~TID~122415~PN~1
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: June 27, 2010 at 5:47 AM / IP Logged  
dustinz_03 wrote:
I understand it is 1 farad for 1000 watts
Always wondered where that comes from... If it's based on the old rule of thumb of 2,000uF to 10,000uF per Amp I reckon I'll bust my guts!
If you cannot maintain the volts, you need a bigger alternator.
If the alternator cannot be "big enough" or the distribution voltage drops to the amp cannot be decreased, then probably a second battery is the simplest - and as close to the amp as possible (eg: a low ESR type).
Chances are that a smallish AGM battery will be more beneficial than a cap (in the same location).
still_walkin 
Silver - Posts: 644
Silver spacespace
Joined: April 18, 2007
Location: California, United States
Posted: July 04, 2010 at 7:08 AM / IP Logged  

well heres the problem you have mismatched subs which is okay if thats your liking . the issue is you have a cap . picture this you have a cup with a hole in the bottom of it you make the hole bigger but dont increase the amount of water you are putting into the cup and the hole is getting bigger thats what you are doing to your battery. what you need is a ho alt big3 upgrade and the biggest battery you can fit under your hood . trust me on this one i had the sdame issue years ago but i didnt have a cap and blinking headlights arent cool. so do some research and post any questions you have

1993 sdv
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alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: July 04, 2010 at 8:56 PM / IP Logged  
I know I'm repeating....
[Read: Now that I see I asked this above. But I'll use the excuse that nobody has yet answered....]
dustinz_03 wrote:
... 1 farad for 1000 watts....
Where does this rule come from? (I suspect I know the answer, but just want to make sure before I....)
Stop here: pointless ramble follows:
IMHO - Interesting too Dustinz' understanding...
But I an not having a go at dustinz_03!! Far from it... in fact I praise dustinz_03 because he(?) is here and asking, has provided good information, and IMO shown good understanding of what is so often told.
"caps are just bandaids for power spikes" - they are usually sold as "solutions for voltage sags"!
But caps do filter - ie, flatten - variations. Hence why removing a cap often results in a LOUDER sound (because of higher peak voltages into amps etc).
But a battery is a bigger filter of spikes.
And what harm are spikes? Damaging spikes should be quenched, and thereafter filtered.
(Caps) "discharging faster than the battery" - do they? I assume that has to do with the discharge knee (electro-chem response time), but does that take into account (battery) plate capacitance and surface charge?
Or do people merely use ESR and internal resistance for that one? (LOL! Electricity travels faster through a lower resistance? I think not!)     
".... the cap is as close to the amps terminals as possible" - absolutely!
But if a battery is placed there instead.....
[The old point that with battery up front, a cap next to the amp reduces dips or sags. But what if a (cheaper?) battery were placed there instead?   Most I deal with did not compare the two! Others tend to go the full hog and have a second large AGM battery there anyhow (for independent battery power; low-ESR; AGM/sealed for non-ventilated use).]
The rest is typical dimensioning, layout & audio stuff that I'll leave to the pro's.
I'm partly venting, partly informing, partly seeking knowledgeable corrections & counters, though mainly pointing out what I see as contradictions as to how caps are marketed etc.
Thanks dustinz_03 for posting his knowledge & understanding. If only I could do it as succinctly!
pngelykn 
Member - Posts: 4
Member spacespace
Joined: October 14, 2010
Location: Georgia, United States
Posted: October 14, 2010 at 6:06 PM / IP Logged  
Yes. No matter what you are driving, what you are installing, or what you are powering; you can never have too much available current. I even upgraded the stator in my old dualsport. (gotta run lights) I've jump-started several cars and trucks without a single problem and I'm only running on 240A. do i need a h.o alternator? -- posted image.
1 Panasonic HU
1 Power Acoustic Amp (sorry)
1 Amazing Box
3 Kicker CVR15s
1 Termlab
36 Hertz
139.5 Decibels
1 Big grin.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: October 14, 2010 at 6:37 PM / IP Logged  
Again - watch those thread dates...
You'd love "hydrogen" sites that reckon they use "surplus power" from the car's alternator. LOL! I bet they'd disagree with you...
Surplus power! That was the first big error I picked in some "highly regarded" reference - the first of MANY errors. So many I assume they were deliberate.
Though I agree with your sentiment, it doesn't mean you have to upgrade.
BTW - I jump started cars with my 1970s Yamaha RD-350 (a kickstart only with ~120W alternator).
Alpine Guy 
Platinum - Posts: 2,478
Platinum spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: October 18, 2003
Location: Canada
Posted: October 14, 2010 at 8:42 PM / IP Logged  
You need another 75-100 amps at idle on top of what your stock alternator produces to have a rock solid electrical system.
2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: October 14, 2010 at 11:44 PM / IP Logged  
Based on what?
Why not 150A?
Alpine Guy 
Platinum - Posts: 2,478
Platinum spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: October 18, 2003
Location: Canada
Posted: October 15, 2010 at 5:22 AM / IP Logged  
https://www.dcpowerinc.com/articles/supply-and-demand-electrical
2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

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