Alt/Cap question

[Patrick18]

My car has a 80A alternator and a expected output of around 1200w. I have already have a poineer head unit and and two boston acoustic component speakers and a diamond audio amp powering them. I plan two put in a 360w Lighting audio amp to power my two 10s. Im afraid my alt will not be able to handle this. I dont want to put alot of strain on my car but really want some lower end sound. Ive heard differnt things about caps and have considered getting one. Somone people tell me they release all the strain on your alternator. What should I do to make sure my alt doesnt die all the time? Is it possible that I could get a bigger alt? If so how much would that cost, or would I be fine just getting a cap or two and a bigger batterie. Thnx

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[Steven 10+ year member]

Hey man.

I think an 80 Ampere alt. is good enough.

Most, and I stress "Most", cars only need between 20-30 amps to run. the rest goes into recharging the battery. Now you add these amplifiers together and it only comes to about 30-40 amps that it will be pulling all the time. ( use the R.M.S. wattage values and divide by 12, then I add about 10% to make up for loss inside the amp). Sure when really deep bass hits it may pull up to about 60 amps total but any extra that the amp needs it'll pull off the battery.

Now the total "regular" pull off the alt will be about 50-70 amps this is below the rated output of your alt and will not cause any problems.

You might consider getting a cap to supply the power for the deep bass hits. This cap will give the amp the extra power it needs, instead of it beng pulled off the battery.

I only have a 62amp alt, and 600 watts of R.M.S. power, plus the cars regular systems. now this adds up to about 80 amps. I should be killing my battery with this setup. but 've never needed a boost. I turn off my stereo when I get out of the car, and then the extra 30-40 amps of power that my stereo was using, recharges the battery. On average, I would say my car runs without the stereo for about 1/2 and hour a day. So you definitly won't have a problem

 

[bean 10+ year member]

My firm beleif is that EVERY amplifier needs a capacitor. You're right Patrick, they save the cars electric system and keep the amp from putting too much strain on your alternator. Rule of thumb, use a half farad cap for every 500 watts of amplifier power. Good luck.

 

[MikeofTulsa Moderator]

well to be completly honest....adding a cap will only help if the charging system is already up to par....otherwise it will just be adding more strain on the system...good luck

 

[bean 10+ year member]

Yep, you're right. But I don't often run into that. Do you?

 

[beerandcope]

the geeneral rule of thumb is for every 100 watts rms that you are pushing you need 0.1 farads. ie 1000 watts = 1farad 2000 watts = 2 farads and so on and so fourth

 

[MikeofTulsa Moderator]

truthfully yes...if your alt cannot handle the load adding a cap will cause more problems...