amperage
 

hi, I actually have a question I have a 1999 mercedes ml320 which puts out 120 amps from the alternator and it uses 77 amps to run the truck with all of the assecories on including lights, heater, wipers and of coarse all ecu's. right now i installed a pioneer deck with two amps one putting out max 2000 watts the other 1600 watts max with two caps one is a 2.0 farad and the other is a 2.8 farad. which are powering 2 sets of 6 1/2 inch components with tweeters 1 set of 5 1 /4 inch components with tweeters and a set or 6x9 pioneers with four pyle tweeters as well as 2 cerwin vega 12inch subs. My question is can I put bigger amps in as well as subs and what is my limit in wattage with out frying out my ecu or my alternator. I will also like to know do you think i need more caps or just one that runs at a higher farad rating.

might want to talk RMS power ratings peak means nothing

just to be safe i'd safe beef up the alternator or do the big 3 or even both just to give yourself a safety net because it sounds like you're running a fair amount of rms watts, and the caps still need to get recharged from somewhere so your alternator will need to work a little harder to charge them (i think, thats what i've heard about them, but i still keep mine because i like the way it looks)

well one amp rms is 900 the other is 1000

1000 watt on a stock alt, batt and wiring is mostly the max you can power...

since you have about 1900watts rms you might want to concider putting a bigger alternator, do the BIG 3 and put in a better battery. battery can wait if its still good

you shouldn't wait for the battery to go down, cause in this case it will probably take the alternator with it. Drawing to much current will not damage your ecu, well not directly anyways. It will however damage your battery and alternator which could in turn damage other things. Getting larger caps will not help as they are STORAGE devices, think of them as quick release batteries. If you are lacking current the only way to get more is a bigger source which is the alternator. Changing the big three will also help because it is a more efficient way of delivering said current. With that model of car it will be very difficult to find anything, so you may have to go the rebuilt alternator route. Good luck in your search though!

Hey smoothbx23,

Assuming a few variables with your system and vehicle using P=I/E.

Vehicle Running= 13.5volts/Vehicle not running = 12.5volts

RMS of your amps =1900watts

Calculations based on your info only (not including any other accessory you're using, headunit/eq/lighting/video etc)

Max current usage : 1900/13.5 = 140.75amps 0r 1900/12.5 = 152amps

These numbers are based on the total max current demands of your gear, RMS values only and not taking into account any other power loss/productions from your amps due to heat.

Like others have mentioned. If you're going to be cranking this system a new alternator and battery will be needed. Also this big three thing will need to be addressed. Great term... wish I was using this terminology when I was in retail, it would have been easier to explain what was being done to my customer's vehicle electrical system :)

Also, do not purchase any more capacitance unless you are planning on competing SPL. Capacitors have a charge/discharge ratio. Meaning it takes more time to charge than to discharge, this will add to your alternator/voltage demands. SPL vehicles typically 'burp' the system for a few seconds, normal audio systems at higher volumes are requiring the capacitor to 'dump' and charge constantly, producing in some systems voltage/amperage lag that is audible by limiting the amplifier power supply needs.

Hope this helps!

Cheers,
Rino

Most SPL guy's don't even use caps because they steal current. There's no substitute for a really good battery and an alternator that can produce enough current. Everything else is a band aid!(accept proper wiring of course)

Depends how loud you listen to your music.

I'll state some basic facts that most people never ever take into consideration.

To gain 3 Decibels of sound, you need twice the amplifier power.

3dB's is how much louder a sound has to be before the human ear can pick it up as being louder(when not specifically focusing on loudness level) ex: If your watching TV and someone very slowly increases the volume level 1dB at a time, you will not notice it getting louder. If the volume was increased 3dB suddenly. You brain would get the clue that it's louder.

To make your ears perceive a sound as being twice as loud. You need a 10dB gain. This takes 10X the amplifier power to achieve.

Most people when listening to music "really loud" are using less than 20Wrms of power for mids. This is where most peoples ears will get uncomfortable if the speakers are reasonably efficient.

For bass..it's all over the place depending on vehicle,, sub, enclosure, port tuning etc etc. But for general listening purposes most people have the subs playing to about half their maximum loudness (1/10th full amplifier power).

This is all only good if music were a sine wave (constant 1 note sound output) but Music is Dynamic and even really bass heavy music and thrash metal are only a 30% duty cycle.

My friend who is an audio engineer and has access to really cool high tech toys did a little test with my car which is running 1600Wrms. We tracked current draw over time listening to some different types of music. Even at the point where I was driving the amps into distortion my averaged amperage draw was under 45amps. This was was music peaking at arund 138DB's from the subs and getting close to 120 db's for Musical peaks.

Playing a 1000hz ans 80hz sine wave My car pulled 192Amps@12.46V.

At Normal pretty loud listenign levels it was avering under 12Amps. with peaks up around 50amps. but averaging around 12.

To make all this into a short version. Unless you crank the balls out if all the time. You should be fine. Specially if your running 0 guage wiring.

Also the caps add amperage to the overall draw, but do help keep voltage a little more stable when your not cranking the beans out things. If you still have the Original battery in the trunk it's time to change it anyways. Interstate makes a good replacement. Also I believe Kinetik makes a battery that fits in your trunk properly if you want to go that route.

For competition usage or if your cranking the crap out of your system all the time a H/O if available if the way to go.