Power question.
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=10889
Printed Date: August 12, 2025 at 11:47 PM
Topic: Power question.
Posted By: Edicius
Subject: Power question.
Date Posted: March 14, 2003 at 3:00 PM
I have a 2002 Chrysler PT Cruiser. My alternator and battery are both stock. I have a kenwood kvt911dvd head unit and a kenwood khd-c710 music keg. I plan on getting two Rockford Fosgate power HX2 12" subs with an Audiobahn A2300HCQ amp. I also plan on getting an Audiobahn A3201Q amp to power my component speakers but have not decided which speakers yet. Will I have enough power to run all of this if I get a capacitor? How big of a capacitor will I need? What is the difference between digital capacitors and non-digital capacitors? Also, I am not completly sure of when to use a two channel amp and a four channel amp. I think that I need a two channel for components..is this correct?
Replies:
Posted By: Big Purds
Date Posted: March 14, 2003 at 3:35 PM
you will need a larger alternator...dont bother wasting money on a cap...
the difference between digital and non digital caps is the digital voltage meter on the top of the digital cap, where as the non digital one doesnt have it...just for show mostly, and if you want to keep tabs on what your voltage is doing...
it depends on what set of components you buy as to whether they are bi-ampable or not...some components are bi-ampable, and then it would be OK to use a 4 channel...you could also bridge a 4 channel down to 2 channels anyway, so its not that crucial whether you have a 2 channel or a 4 channel...
Posted By: Edicius
Date Posted: March 14, 2003 at 3:43 PM
What kind of alternator do i need to buy? What about batteries? I have heard that if you have over 1000 watts you need a cap is that wrong? Would I be ok with just the subs and the A2300HCQ until I get a new alternator?
Posted By: bberman1
Date Posted: March 14, 2003 at 3:49 PM
Alright as far as the subs and sub amp goes excellent choice you will be very happy with that setup. Now for your mids and highs what is your plan? Are you just upgrading your fronts with the components? Or do you plan on upgrading your front and rear speakers? I would suggest that you do both front and back. Now as far as a 2 channel or 4 channel for your mids and highs that’s up to you. If you have a 2 channel then yes you can run your components off that. If you plan on upgrading front and rear then you can bridge them together and run your fronts off one channel and rears off another. This will allow you to run 2 sets of speakers (front 1 channel and rear 1 channel) off a 2 channel amp. The only problem with this is you lose the balance control. However if you plan on upgrading both front and back speakers I would suggest that you get a 4 channel (one channel for each speaker) AMP such as the Audiobahn A4125HCQ. As far as the power goes you will need to get a high out put alternator. I calculate that the A2300HCQ and A3201Q alone with out the load of the rest of the car at full power will use 204 amps. Now a cap is not going to substitute for your lack of power/ current. You can read about what a capacitor will do for you here https://www.eatel.net/~amptech/elecdisc scroll down on the left and click on capacitors, you will want to read the part about stiffening capacitors. Now for the ratings of the capacitors the rule of thumb is 1 farad for every 1000 watts rms so for a set up of 4000 watts you would need a 4 farad cap. The difference between digital and non digital is a digital has a digital voltage display and the non digital doesn’t. Now this will not affect its performance it’s more for looks. But like I said before a cap is not a substitute for a charging system upgrade they are meant to run in conjunction with the proper sized charging system. If you have any more questions or need me to clear up something let me know.
Posted By: Edicius
Date Posted: March 14, 2003 at 4:06 PM
I am going to upgrade both the front and rear, I just have not decided on the speakers yet.(any suggestions?) How do I know how many amps I have available now? About how much does an alternator cost with and without installation? Will just the A2300HCQ and the subs be too much for my stock alternator? What about battery upgrades? Thanks for the info!!!
Posted By: bberman1
Date Posted: March 14, 2003 at 4:50 PM
If you’re going to be upgrading both front and back speakers I would go with a 4 channel amp instead of a 2 channel. I don’t know how big your alternator is but can tell you that the A2300hcq alone will use more power than your stock alternator can put out. As far as the price of the alternator goes depends on the company you go with. I would call this guy C.S.A
nathanpeddicord@yahoo.com or call at 1-334-712-9955 or 1-334-791-6272 they build lots of alternators for competition and have very reasonable pricing. As far as the battery goes I would suggest that you get an Optima yellow top battery as well as the alternator. When you upgrade the alternator be sure to upgrade the cables between the alternator and the battery as well.
Posted By: bberman1
Date Posted: March 14, 2003 at 4:56 PM
I emailed you a article on car audio and your electrical system let me know if you don't get it
Posted By: Edicius
Date Posted: March 15, 2003 at 8:56 PM
What should I look for in a battery?
Posted By: Edicius
Date Posted: March 15, 2003 at 9:38 PM
In the article that you e-mailed me, it said... -- "Here's a simple formula: divide the RMS power rating of the amplifier (in this case, 300 watts) by the amount of voltage your car's electrical system will produce. Most cars have a standard 12-volt system that actually cranks out about 13.8 volts with the motor running. So, 300 watts divided by 13.8 volts equals 21.7 amperes of current. Your car's electrical system will need to produce an additional 21 amperes (the term for measuring electrical current) of electrical current to power the amplifier and subwoofer at a reasonable performance level." If I am calculating this for a multi-channel amp do I add the rms power rating of all of the channels together and then divide it?
Posted By: dragonrage
Date Posted: March 15, 2003 at 9:39 PM
Don't replace the battery for audio. Just don't. If you draw so much current that you need to touch the battery, then you need a larger alternator. I'm too lazy to look up specs on those amps, but if you're going to go crazy, add a second alternator instead of replacing the alternator. Also, a capacitor will help if you have a big system, but it will not be anywhere near a substitute for the alternator. And whatever you do, do _not_ add a second battery unless you want to be able to run your system for a little while in acc on AND you have a very high current alternator. Letting the system run from battery with a weak alternator just gives the alternator more work to do, and ultimately ends up making matters worse. If your system is really big, your alternator is good but you idle your car a lot (much of your driving being stop and go traffic, for example) then you could look at battcap, but like I said before it is not a replacement for an alternator. ------------- 2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?
Posted By: Edicius
Date Posted: March 16, 2003 at 1:09 AM
Is there anything that I need to know about my car to buy a more powerful alternator.
Posted By: dragonrage
Date Posted: March 16, 2003 at 7:04 AM
Just make, model and year...Knowing what it looks like would be a good idea too, just so you can make sure the new one looks the same (but never go just by looks)
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2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?
Posted By: bberman1
Date Posted: March 16, 2003 at 9:28 AM
If you’re going to upgrade it than try and get the largest one you can. It can’t hurt to have too much power. You should be able to find a 200 amp with out a problem. Here are some links to sites https://www.wranglernw.com https://www.mralternator.com or call C.S.A. nathanpeddicord@yahoo.com or call at 1-334-712-9955 they do lots of alternators for comp cars
Posted By: Edicius
Date Posted: March 16, 2003 at 6:22 PM
In the article that you e-mailed me, it said... -- "Here's a simple formula: divide the RMS power rating of the amplifier (in this case, 300 watts) by the amount of voltage your car's electrical system will produce. Most cars have a standard 12-volt system that actually cranks out about 13.8 volts with the motor running. So, 300 watts divided by 13.8 volts equals 21.7 amperes of current. Your car's electrical system will need to produce an additional 21 amperes (the term for measuring electrical current) of electrical current to power the amplifier and subwoofer at a reasonable performance level." If I am calculating this for a multi-channel amp, do I add the rms power rating of all of the channels together and then divide it?
Posted By: bberman1
Date Posted: March 16, 2003 at 6:33 PM
Yes add the total rms output of the entire amp then do the division. That tells you how many amps that amp will be using. If you have more than one amp add up all the wattage and then divide. So if you have a 500 watt rms amp and a 300 watt rms amp you would add 500+300 =800 then divide by 13.8.
Posted By: Edicius
Date Posted: March 16, 2003 at 6:42 PM
I know that was a dumb question...Thats what I thought but, I just wanted to be sure.
Posted By: bberman1
Date Posted: March 16, 2003 at 6:46 PM
there is no dumb question !
Posted By: Edicius
Date Posted: March 16, 2003 at 7:13 PM
Thanks...The way I calculated it, It came out to (282.608695652173913043478260869565) Thats for the Audiobahn A2300HCQ and the Audiobahn A4125HCQ....so I will need to get a 300 amp alternator or should I get a larger one? Where do I get these installed? Why does it matter if it looks the same? If I buy a capacitor will that add to the amount of power I consume? What about other add-ons(neon, videogame systems, video monitors, etc.)?
Posted By: bberman1
Date Posted: March 16, 2003 at 7:46 PM
I calculate 231.884 that’s 1000 ( A4125HCQ0 + 2200 (A2300HCQ- that's 3200/13.8 = 231.884 Now that figure is calculated with you running the A4125HCQ at 2 channels @ 1 ohm. you will actually only be using 125 X4 @ 4 ohms so that's 500 watts + 2200 =2700/13.8 = 195amps at full volume. Now you will be fine with a 200 amp alternator but if you can find one larger go for it.
Posted By: Edicius
Date Posted: March 16, 2003 at 8:52 PM
The A2300HCQ is 1200 x 2 that's 2400. The A4125HCQ is 375 x 4 that's 1500. 2400 + 1500 = 3900. 3900 / 13.8 = 282.608695652173913043478260869565 https://www.audiobahninc.com/products/results.asp?categoryID=9&seriesID=21# If I buy a capacitor will that add to the amount of power I consume? What about other add-ons(neon, videogame systems, video monitors, etc.)?
Posted By: bberman1
Date Posted: March 16, 2003 at 9:10 PM
Yes it can put out 375 X 4 @ 1 ohm which is 1500 watts but you will almost never run that kind of power on that amp if all you have is 2 sets of 4 ohms speakers. so if you run 2 sets a 4 ohms you will get 125X4= 500 so you will have 500 + 2400( sorry not 2200 as I figured before) will give a total of 2900 watts rms so if you calculate that it is 210 amps at full volume. Now trust me it will be very rare that you pull a full 210 amps for both amplifiers. But yes you are correct if you have the full 1500 watts which you will never do and the 2400 watts then yes you would be pulling about 280 amps (this will never happen) if you get a 200 amp alternator you will be fine. If you try and find a 300 amp alternator well then good luck. That’s when you get into multiple alternator setups and the cost on that is in the thousands.
Posted By: Edicius
Date Posted: March 16, 2003 at 9:30 PM
" Now trust me it will be very rare that you pull a full 210 amps for both amplifiers. But yes you are correct if you have the full 1500 watts which you will never do and the 2400 watts then yes you would be pulling about 280 amps (this will never happen) if you get a 200 amp alternator you will be fine." So is it ok to go over what the alternator can put out? If I buy a capacitor will that add to the amount of power I consume? What about other add-ons(neon, videogame systems, video monitors, etc.)?
Posted By: dragonrage
Date Posted: March 17, 2003 at 8:21 AM
If you're doing other addons like that, you will probably need a second alternator.
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2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?
Posted By: bberman1
Date Posted: March 17, 2003 at 8:55 AM
Trust me you will never pull a full 200 amps. I have had some very large systems and have had the current draw measured it never will come close to 200 amps. On my last system I ran (1) Audiobahn A4125HCQ to power my mids and highs and (2) Audiobhan 18001D Amps to push (2) Audiobahn AW1208Q's now that’s a total of 4100 watts RMS in the configuration I was running it. Now if you do the math I should need 297 amps to run it a max volume. Now I only have a 200 amp alternator. When I put it on the alternator shops machine that tests how many amps your pulling if only drew a little under 200 amps with the car running and my neon’s and all that good stuff. The volume was up as high as it could go with out distorting about 75 %. Now I now that (2) my amps were class D which dose make a difference but what im trying to say is you will probably never pull over 200 amps. Now if you want to go for 300 amps well then go for it. And to answer your question about going over the alternators max no it’s not ok that’s how you blow an alternator. And if you add a capacitor that will not affect the amount of power that you consume. As far as the neon’s and all that they all add about 2 amps each. Have you talked to any alternator builders about this yet and gotten any prices?
Posted By: Edicius
Date Posted: March 17, 2003 at 1:22 PM
I emailed that guy that you told me about but he was out of town this weekend so we are just starting to talk today.
Posted By: Edicius
Date Posted: March 17, 2003 at 5:04 PM
OK, another question...I found a website that says my stock alternator is 120 amps. Do you still think that it is not enough for just my subs, even after you said that I will not pull all that it is rated at?
Posted By: bberman1
Date Posted: March 17, 2003 at 6:36 PM
Go for at least 200 if you can go bigger with out any major upgrades (2nd alternator) then go for it. Now that guy at C.S.A. may be able to get you some more power then some of the other manufactures out there. But don’t settle for anything under 200 amps. And you won’t come close to the max volume which will use the max amps that you calculated.
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