it is common for the idle current to go down ot the 12v range, but at anything over 1000 rpms it should be closer to 14

don't forget the pics

 

I did mean at idle, sorry i didn't include that. But yes you should hop back up when you are on the throttle at all. I guess im just not the best at standing at my trunk with a multimeter monitoring my volts while also driving the car...

 

the owner of EW here taught me that a Alt will do max voltage & Ampsaround 2500RPM(normal driving conditions) and depending on RPM, volt and amps fluxuate inversly.. but i dunno bout that part. said that if a alt is spinning faster, it will make more volts but less amps, and vise versa.

best thing to do is upgrade alt. spend 500 bucks on a nice HO alt. then buy a kinetik or a red top for under the hood, and stay away from Caps/2nd batt unlessrest of electrical system is up to par.

and my 96 camaro stayed around 13 volts at 2500RPM with 2 L7s and a PCA2000D. i had a HO alt and red top and big 3 etc. it hardlyever fluxuated, but i never pushed system to the max(was WAY to deffening and would flex rear window like a ****).my ION, i havent done alt to yet(and prolly wont, selling it[8D]), but i have done 2 wires of the big 3(alt - batt is already 4G, and batt is in trunk[&:]) and im only running a 60amprage amplifier to a single D3.

 

voltage and current and direclt related, the faster it turns the more you have of both. Not sure where you heard that or who told you?

I spent $120 on my 200A alt, and and hour installing it as well as a new battery. I scrapped the optima because here in the desert of phoenix, you are lucky to get 3 yrs out of a good battery. Because of this the deep cycle batteries are not any better the the regular ones here I went with the highest CCA I could find.

With the alt and the battery, as well as some UD pullies(I feel a little silly with pullies and a HO alt) at night my voltage can still dip below 12 at idle if I am not carefull. I can see this easily with the voltmeter and amp power meterI installed in the dash and can also see that when the amp is sucking alot of current you can see the voltage drop. My pullies came with instructions to bump the idle up 1-200 rpm to fix this and I just have not worked on my intake to fix it.

 

didn't figure the last part was right, and the owner of electronics warehouse where i'm at. but i've heard quite a few times a alt makes most amps and volts at 2500 rpm.

the HO alt for my 96 was 480.. lol, was a 240A alt.

 

It will make its rated output in current at that standard rpm and the designer's specified voltage..

I think we need to provide you some clarification....

Voltage and Current Work inversely. They arerelated toPower using the equation P =VI. Pis power,V is voltage, and I iscurrent.If your car draws a constant amount of power you can still see fluctuating voltages becuase of the current output changes from RPM in the alt. The voltage an alt puts out is related, but independant of the current production of the alt. Avoltage regulator regulates the voltage to a certain level that is above the 12.5V Nominalcharge of the battery. In order to charge the battery you must have a voltage differential so that currrent can travel into the battery. Anywhere below the nominal charge of the battery and you are draining the battery.

 

Whoa, sorry but I just have to post after reading this thread. I guess I should start by saying that I don't work at circuit city, I work for a major batterymanufacturer.

I don't know why you are getting flamed so much for putting a compact suplemental battery in the trunk, my company as well as others make batteries specifically for that purpose. The only problem that you could run into is fume ventilation if it is a flooded type (filled with liquid electrolyte) battery, and even that could be alieviated by placing it in a battery box that is vented to the outside of the vehicle. If it is an AGM (gell) type it's perfectly safe AS IS.

As a general rule of thumb though, garden batteries are pretty low quality/output and will make little difference in a car audio application. Ifyou are set on buying a yellowtop, just mount it in the trunk and keep your stock battery under the hood, both in parralel, no special alternator needed.

I also read in here where someone claims that you need a 200 amp unit with underdrive pulleys; total B.S. The low RPM output ofa 200 amp 3G is often lower (at underdriven rotor speeds) than a 130 amp large case 3G. Funny how some of the most aggressive flamers on here seem to be the biggest distributors of mis-information. If you ever want to know the REAL deal on batteries or alternators, feel free to ask. (It's what I do for a living)

 

You work for a battery manufacturer, but your talking about alternators? I make parts for farm equipment, so i know how to harvest beans?

Don't think anyone said you need that, ttocs said thats what he currently has in his car.

 

just guessing, but it would make a lot of sense to know all about alternators especially when they charge the product you make.

you make parts forfarm equipment so you should know how those parts react to weather, stress, and wear/tear.

 

Wow, first post and you choose a doozie! working for a maj batter manfdoes not make you an expert in batteries, heck you could sweep the floor and swab the toilets. My fulltime job is as a tech at a MAJOR semiconductor manf and I hate computers, don't ask me about them. Car audio was the job I had through school and now part time I have been doing it for almost 15 yrs. So please, join the circle but introduce yourself a bit because until you can show you know more then the average person about anything I will treat you no different the walmart customers getting tips from a walmart empoyee....

So have you ever considered that adding a 2nd battery, even a small one will place an additional load on the alt? It does and will cause problems even with a high quality battery, but especially when it is a stock alt. The fumes are a problem that has to be considered, as well as leakage and shorting as I am willing to bet there is not so much as a bungy cord holding the thing in place and how high should he fuse that wire? We can wait for the pics if you like but I will bet ya...

How come we don't mix a AAA batter with a D cell? They are both 1.5 volts right? ThereIS a difference in those two besides just the size, although they are not nearly as big of a difference as the one you are recommending and no where near as dangerous.

If this was a good idea, your major battery manf would have candy colored garden varieties batteries right next to their caps, which is next to their batteries and every ricer from here to china would have 2 or 3 rather then their caps.... It has taken the better part of the last 10 yrs to get the word out that caps are good paper wieghts but they are still selling them to people that don't know any better. What size is your cap that you will replace with a new, 2nd battery?

I was the first one to say that I feel silly with udp and a ho alt but the only time I have a problem with voltage is when I am not moving. I tend to drive my car more then I just sit in it so I feel I still get the benifits of the pullies and you will not see me jump starting my stang. Youwill also not see itin any elctrical fires since I know that everything has been proplerly installed with the correct fuse ratings, the article he linked to didn't mention anything about safety, fuses, ect. Just slap in a 2nd battery, what can go wrong right?