Alternator or Capacitor

[Dooka4u4]

I have a sony xplod 760 watt max amplifer in my 94 ford explorer with a stock alternator that i believe is rated at 95 amps. The amp runs fine to a point but then as soon as i crank it real high and the subs kick it drops the alternator level from 14.4 to about 11 or so. Im not sure if a capacitor will be enough to solve this problem. I also am running a Pioneer 480 watt max amplifier for the full range speakers. If i got a capacitor would i need to get 2, one for each amp. Before i got the sub amp the car handled the other amp with no problems...Also is Lightning Audio a bad brand of a capacitor or are they all pretty much the same. I know the total solution would probably be to get a new alternator and capacitor but do you think that just puting in two caps would keep the level dropping so dramatically. Im not an expert at this so any advice would be appriciated.

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[Phatillusion 5,000+ posts]

Like Zane has said so many times. A capacitor is just a band aid. Your charging system is already having problems. Your voltage meter will still drop with the capacitors. How much, I really don't know, with a capicitor it might help a little, but what good is a capacitor when your charging system isn't strong enough. A larger altenator would completely fix the problem. They are relatively easy to install.

 

[ramos 5,000+ posts]

Let's see here. I'm gonna break out a little math on ya //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

First you say your Explorer has a 95 amp alternator. Figure that your vehicle with all acc. require 60% of the total output of your alt. So multiply 95 x 40% or .4 and you get 38. So that means you have roughly 38 amp reserve capacity.

Now lets look at the current draw of your amps. You said you have one 760w max and one 480w max. So your looking at roughly 620w RMS. Now if we take 620( the RMS power of the two amps combined) and double it we get 1240. Now divide 1240 by 13.8(average output of an alternator) and we get roughly 90 amps. So your system is pulling roughly 90 amps.

As you can see you are overtaxing your electrical system. I highly doubt a cap or two would cure your problem. You might luck out and find a alternator with a higher output at a local part store.

 

[LuRp 10+ year member]

ramos... applaud. I am an EE major, and i have never to this day heard anyone layout an equation like that as clear as you.. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

LuRp

 

[cmp69 10+ year member]

BRAVO!!

 

[audiolife 5,000+ posts]

umm i doubt it will draw 90 amps continuous but i might make a suggestion.....get your alternator rebuilt to about 120 and add a 1 farrad cap......and make sure your battery is in good shape....the alt rebuild will cost you about 100 or so.

 

[ramos 5,000+ posts]

Thanks //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

No it won't draw it continuasly. But at times it will draw more than that. It all depends on the music and how loud you listen to it.

 

[audiolife 5,000+ posts]

o0o really? can i let you in on somethin......it wont.... =) its kinda funny my old system had alot more "draw" than that........................now if you are talking about that .1 millisecond where it might get close the cap would take care of that.....and the extra 25 ampers of current would and should do it.......actually i bet he has a bad ground be it on the amps or a chasis ground if his system is reacting that bad. caps have a specific purpose and it isnt for a bandaid people try them for that but in reality ................ they can enhance performance but for me they would be a henderance ... i have an ohio generator 290 amp alternator with variable voltage between 14-20 volts. being your into ee you should know why as i was in eet o0o 5 years ago......=) and if you want to question it i will give you an example........... kirchoff's voltage law

 

[BlackSunfireGT 10+ year member]

This is a saying that is common among video rental stores but can work well with alternators. Be kind, rewind. In other words, look into getting your alternator rewound to a higher amperage, you can probably snag an extra 30-40 amps outta your stock alternator, call some local shops and ask.

 

[audiolife 5,000+ posts]

see^^^^^!!! most average competitors run maybe a 150 amp alt.........with alot more power than this guy has.

 

[LuRp 10+ year member]

The ultimate pupose of caps are to eliminate the bang that comes out of the speakers when the car turnes on and off.... nad please, 4 years is enough i dont need to be reminded of KVL in an car audio board

LuRp

 

[audiolife 5,000+ posts]

lol you got me on that one...but they basic voltage stabilizers too.

 

[ramos 5,000+ posts]

Seems to me the only suggestion I made was an alt with more output. There are several ways to achieve this. Most of which have been added.

I would lke to hear how a cap can enhance performance other than keeping your headlights from dimming.

And by saying the amps won't draw more current. You mean the amps will never put out more than the RMS wattage. So I guess musical peaks have no effect on the output power of the amplifier. Oh well my mistake

 

[zane 10+ year member]

Originally posted by ramos Seems to me the only suggestion I made was an alt with more output. There are several ways to achieve this. Most of which have been added.

I would lke to hear how a cap can enhance performance other than keeping your headlights from dimming.

And by saying the amps won't draw more current. You mean the amps will never put out more than the RMS wattage. So I guess musical peaks have no effect on the output power of the amplifier. Oh well my mistake

Once again. Agreed.

I will say it again also- If your cars charging system can not keep up (IE -voltage drops) then a cap is only a band aid to a larger problem. Now, on a properly functioning charging system, a cap can be beneficial by supplying small ammounts of reserve power for a deep bass hit. A caps sole purpose is to aleviate strain on the alternator durring those brief musical bursts. However, if your alternator has problems keeping up- what good is a cap?

take it easy,

-zane

 

[audiolife 5,000+ posts]

to increase 10 volt capacity? lolol