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Discussion Starter · #1 ·
Im installing my sound system this week and I have a question about the stock charging system... (don’t know where to post this question)


Okay... How many amps does our alternators put out? Im installing a big sound system (Precision Power PC1800 800 watts at 2 ohm's)
This amp can draw up to 133.3amps (PPI Tech) but im gonna be at 3 ohm's (worse case 100 amps). I bought a 4.5 Farrad Cap so far, and my battery is on order (dry cell). If you guys could let me know I would appreciate it.
:D
 

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Man, that sounds like it would make a good Wierding device.
I would think the stock charging system is much lower than 100amps, but i may be wrong.
I do know i aquired a truck altenator that was ~ 85 amps if my memory is correct.
 

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I have a V8 Dakota too,,and i have a HUGE sound system.
1 kicker KX1200.1 1 ohm 1540RMS draws 144 AMPS)for my S12-L7
1 KX 800.2 (Draws about 70 AMPS) for my Boston Pro speakers.
1.5 farahd capacitor,,and a 115 AMPS Naval use battery.
The battery just go away in 3 minutes is ridiculous.
Always when i go in my car the sound is dead,so when i turn the car on then the rear battery start charging the rear batter so i can turn the sound up.
My dakota alternator is 85 AMPS hour i think,,and that is really a good alternator.
Our WRX have a smaller alternator but i think it can make 65 AMPS hour or something like that.
I searched the dakota and the WRX manual and couldnt find the alternator specs.
Take a look at pics of my 350 HP V8 Dakota(now with broken tranny Automatic,,and with the brake rotors all twisted)
Tuca33 Home Page =)
Click the left links where it says SOM - FOTOS,Mais FOTOS,FOTOS FOTOS,,and there are some pics of my WRX also:D
New pics with clear side markers and clear blinker covers,STI Child eating hood scoop,Water spray kit,HKS Ground mod(Very good mod for AUDIO CARS),STI Shifter trim..
Those new pics will be uploaded soon
Thanks
Tuca;)
 

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The WRX alternator is rated at 75 amps.

An extra battery will only provide longer listening time when the engine is off. When the engine is running the alternator will be supplying all the power. The battery(s) is only a reserve when the engine is running, it will only supply power when the total power consumption (engine, lights, stereo) is greater then what the alternator can provide. Extra batteries will also present an extra load on the alternator.

Capacitors only supply transient power. Basically, when the amp draws a large amount of power very quickly, like when a bass note hits, the capacitor will supplement the charging system. Capacitors are very useful in keeping your headlights from dimming when the bass notes hit.

Your amp will never draw rated current (133 amps) for more than a few milliseconds at a time while listening to music. I ran a PPI PC 4800 (100wpc X 4) and a PC 2600 (150wpc X 2) with a 1.5 farad cap in my 98 Accord (85 amp alt.) for 2 years and never had a problem. You will be fine wth the stock alternator for now, although I would recommend you upgrade to a larger one (100+ amps) when time and money permit. Large, power hungry audio systems will send the stock alt. to an early grave. Better safe then sorry :D
 

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My KX1200.1 came with a 150 AMPS fuse.
and the 800.2 came with a 100 AMPS fuse.
They are very powerful.
They are rated 1540 and 970 RMS respectively.
my 115 amps battery runs out in 3 minutes.
If the WRX alternator is 75 AMPS,,then it will not supply the good juice we need.
Tuca
 

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Discussion Starter · #6 ·
Thanks for the input guys.... Is there an aftermarket Alternator for our cars? I know Stinger makes one... the one i saw looked like a freakin boat anchor. (Must have been a GM Alternator) :p
 

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4.5 Farads. Man that is one huge cap. They usually recommend 1 Farad for every thousand watts.

Caps are only good if your electrical system is working good in the first place. If not, your cap is just acting like another load and makes your alternator work harder to keep it charged.

I would suggest buying a voltmeter so that you can monitor how well your electrical system can handle the amplifiers. If you notice that the voltage is running around 12.6V with the car on and your radio blasting i'd be concerned since that means your alternator is now trying to keep the battery charged along with running all the accessories.

PPI Amplifers are very nice. I have owned a few of them. The one thing about them is that they can draw a lot of current. They use a regulated power supply. Meaning that it will put out its rated power over a specific (12-16V) range. If the voltage starts to dip, the amplifier starts demanding more current to maintain its rated power.
 
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