HA! Got the questions...
 

Ok, it took me a while to think of the right way to ask this but I think I got it:

What limits how many amperes your amplifer is taking in? I am guessing that the alternator limits the ampere output for long periods of time (for example my amplifer should not take more than 105 amperes because that is the highest amount that my alt puts out) but what about when the car is off? What limits the ampere output when the car is off???? I mean, I know that it is the battery but will the battery be able to put out more than 105 amperes while the car is off??? Is this where deep cycle batterys come into play????

Also, the same goes for voltage. Can you regulate voltage amounts some how? Say, for example, when the car is off I have 12.5v but I need 13-14 volts? Can you raise the voltage by any means when the car is off??

Thank you very much for any help :). I am sure these questions are hard core to answer so thnx fer takin the time :D.

when the car is off the battery is everything. Whatever the limit of your battery, in terms of sustained current output, that is your limit for sustained listening. Now remember that batteries are designed to generate a lot of amps for cranking the engine, so for short bursts your battery will supply quite a bit of current...400-1200 amps depending on the battery but remember it won't last for too long without being recharged...enter the deep cycle battery which has a much longer sustained output. As for the voltage, sorry, again you're limited to what the battery puts out. I know you're probably thinking, if i had a battery that was 14 volts that would be great...right. Unfortunately, you would have to change your alternator also to charge at a higher voltage, 15.5-16 volts, otherwise the battery would not charge. Your car's components may not like such a high voltage, they may work, but probably won't last for long. In SPL I'm aware of amps that are 17-18 volts, but I don't think these are daily driven vehicles...someone in spl can correct me if I am mistaken.

First - avoid ever running your system when the car is off.

Running or not, when you exceed the output of the alternator, the excess is provided by the battery. Two ways to look at the power you can get out of a battery:

1) Cold-Cranking Amps (CCA) - A rating that is used to define the battery's ability to start an engine under low-temperature conditions. BCI defines it as "the number of amps a lead-acid battery at 0ºF (-17.8ºC) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt lead-acid battery).

ie. A 'standard' 650cca battery can provide about 650amps for 30seconds or so. After that it's dead.

2)Reserve Capacity (RC) - "the number of minutes a new, fully-charged battery at 80ºF (27ºC) can be discharged at 25 amps and maintain a voltage equal to or higher than 1.75 volts per cell" (i.e., 10.5 volts for a 12-volt battery). This rating represents the time the battery will continue to operate essential accessories in the event of a charging system failure.

So you can see that the more you draw, the less time you have. Thus - always have the car running when playing even at moderate volumes.

Oh - I copied that info from Interstate's site.

ohhhhh. That makes soo much sense. And I like what I am hearing :). So the amps will pull how ever many amperes they need from the battery (within reason haha, and thats a rehitoricle question unless I am wrong :laugh:)? I am talkin just for burpin other wise I never run my system without the car on.

But the volts things kinda stinks. Is it possible for a person to get a battery to put out 13-14 volts while the car off :dunno:??? Cuz everytime i turn my car off my volt meter reads 12.3.

If not then how do some people compete so well cuz amps like the orion2500d do 2500Wrms at (I THINK) 14.4 volts so in other words that amp can't do its best when the car is off meaing it would suck in an spl contests. haha, its a big assumption but it makes sense to me :).

Thanx dukk and veeman fer the detailed replies :D:thumbsup:.

this just hit me. wut happens if you do use the system with the car off on a regular basis???

Except if the SPL competitor has his electrical system designed to provide the higher voltage, as Dukk mentioned. If you have a high power amp, you probably have an electrical system capable of powering it.

Yes an amp will demand current, and lower the voltage gets, the more current the amp will draw.

Yes and no. Yes you can buy a device that will make sure your amps always get 14volts. No it cannot alter physics and it still draws power in at battery voltage. The difference is made up in the current it draws from the battery is higher than the current the amp draws from it. Trust me - you don't want it. Not only is it expensive (ie more than a new alternator and pair of Optimas) but it is bad news with respect to current draw.

As Veeman mentioned earlier, some people do run 14volt or 16volt setups but generally not on a street driven car. The alternator has to run about 2v above static battery voltage to charge it and most car electronics don't like that much voltage.

That's why many manufacturers also rate their amps at 12.5 volts. You're right that you won't get the same power at 12.5 as opposed to 14.4 volts, but most spl amps and many good brands under rate their amps anyway, so you probably end up pretty close to the rated power at 12.5 volts. Keep in mind also that many amps that use tightly regulated power supplies won't lose as much power at slightly lower voltages compared to unregulated amps. This by no means makes them better, just different, and may work in some situations better or not as well. I like both types...a good amp is a good amp! There's nothing you can really do(reasonably) with the car off to bolster the battery voltage as far as I know. Your alternator runs at 14-14.5 volts, this higher voltage is what allows it to charge your lower voltage battery(12-12.5 volts). If you were to up the battery voltage, it would not charge at all or it would but very slowly...not good!

wow, that is pretty friggen technical. I suppose it is back to bcae1.com to start learnin the equations better so I can calculate what my amp does at 12.3 volts. haha. Thank you a bunch guys.

If you discharge a normal car battery until dead more than a few times, it will need replacing. Some are better than others. Some will need replacing only after discharging 3 times, others 10times or more. Normal car batteries are NOT designed for much more than starting and running a few accessories for a few minutes or so.