Headlights dim when the music plays

What to do to give your car's electrical system a power-up


Buck Pomerantz

Buck Pomerantz was born and raised in Philadelphia. His parents bought their first television set when he was born. He figured out how to run it by the time he was two. Besides athletics, his formative interests included electronics, amateur radio, music, and stage crew work. He got his BA in writing from Brown University. Then he joined a rock 'n roll band as their soundman and moved to Charlottesville, Virginia. After that venture failed, he spent time in Boston, New Orleans, and Berkeley. He worked in a music store in Austin manufacturing, installing, repairing, and operating sound systems for recording studios, clubs, and bands. He moved back to Charlottesville, ran a little recording studio and finally joined Crutchfield as a copywriter. He has 2 grown children and 3 grandchildren, but after a good nap he can still rock out.

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Your headlights dim when the stereo pulls too much power out of your car's electrical system. This usually happens only in large, multiple-kilowatt sound systems. But sometimes even modestly powered systems can stress your car's electronics, especially during a sub amp's burst of energy when it produces the sound of the beat. Every part of the electrical system suffers because of the amp's sudden demand on the limited supply of power, even the amplifier itself. Your eyes are just more sensitive to the change than your ears, and you notice your headlights dimming along with the beat.

There are a few actions you can take to solve this problem. There are also some strong and differing opinions about the order in which you should do them, or even their individual usefulness. The following is my contribution to the argument.

T-Spec battery terminal

Sometimes all you need is a new battery terminal.

Check all power and ground connections, and the battery itself

The first thing you should do is make sure all the surfaces used in power and ground connections are scraped down to bare metal, clean, and all the connectors and the battery terminals fastened tightly together. If that doesn't do it, take your car and have its battery load-tested at an auto parts or battery store. They'll often do it for free and can recommend the proper replacement if they find your old battery has problems. Car batteries rarely live to be four years old, so don't think you're being cheated when they tell you your old battery isn't holding its charge. A weak battery can often have enough juice to start your car but not be able to handle the quick jolt of demand when your sub amp hits.

If you do decide you need to replace your battery, consider getting an XS Power battery from Crutchfield. XS Power batteries feature a sealed absorbed glass mat (AGM) design, instead of the standard liquid electrolyte design, so they actually store energy — meaning you don't have to add a capacitor to your system to get a quick burst when you need it. We carry a full assortment of the most popular sizes available.  We even have models which fit many European applications such as VW/Audi, BMW, Mercedes, and Jaguar.

T-Spec cap

T-Spec 3.0-Farad capacitor


Adding a capacitor to your system does not increase your system's power capacity. But if your lights dim only occasionally, and only on the loud drum beats, then a capacitor may just be the cure. A capacitor smoothes out the power demands by providing a short burst of energy when needed. I recommend 2 farads of capacitor for every 1,000 watts RMS of total amplifier power. That's more than the usual recommended dose, but it should ensure a quicker recovery time for the cap to be ready for the next thump.


XS Power BIG3XS big 3 wiring upgrade kit

The Big Three wiring upgrade

A good, cost-effective improvement is to perform the "Big Three" electrical upgrade. This will vastly improve your vehicle's electrical system, allowing more current to flow easier to all components. This upgrade replaces or augments three key cables in the electrical system with 1/0 or 4 gauge wires: the battery ground to chassis wire, the chassis to engine block wire, and the alternator plus to battery plus wire. This increases your electrical system's current flow capability, ensuring a more consistent voltage under varying demand conditions.

An unfortunate possible side effect of doing the Big Three is that occasionally it only makes your lights dim even worse. This happens because the amplifier is now able to suck juice better from the system through the bigger straw (the new cables).

High output alternator

The alternator is the ultimate source for all of your vehicle's power when it's running. The battery starts the engine, but the alternator takes over when the motor starts to turn. If your sound system demands more power than your stock alternator can supply, then you will benefit by upgrading to a higher output alternator. Replacing your stock alternator with an "HO alt" may seem like an expensive solution, but if you've invested in a sound system that draws this much power, you shouldn't mind solving this problem of supply and demand by increasing the supply of power.

For example: producing a 1500 watt output requires about 217 amperes of current from your car's system. It's actually about a third of that for music, which doesn't put out full power all the time — but it's still a lot of current.  Most stock alternators are in the 80-120 ampere range and can only supply about 40% to 50% of that for non-automotive uses like amplifiers.

A 250 or 300 ampere aftermarket high output alternator should provide enough power for all your car's systems and your high-powered stereo too. Keeping that in mind, calculating the required output size of a high output alternator is not easy and should only be done while consulting with the new alternator's vendor or installer.

XS Power battery

XS Power car batteries

Adding a second battery

Another method is to add a second battery, often back near the amplifier. This, in effect, provides another source of power available to fill in the gaps when the system needs it. When the power is asked for, it comes from the batteries. Two batteries wired in parallel act like one battery with twice the capacity. Crutchfield carries secondary battery wiring kits that feature all the hardware necessary for adding a second battery to your system.

XS Power secondary battery wiring kit

XS Power AK3500 secondary battery wiring kit

A second battery becomes almost necessary if you play your music a lot with the engine turned off. Some people use isolators between their batteries, so that the one used to start the car won't get drained by the amp's pull. And it's a good idea to only hook up two batteries of equal strength and age. The stress of two different strength batteries constantly cycling charge between themselves to equalize the voltage leads to a shortened life for both batteries.

Note: Working with a car's electrical system can be dangerous. Tools and jewelry can be welded by the inadvertent discharge of a battery or capacitor. Sparks could fly, igniting flammable gases. Batteries have been known to explode when overstressed. (I know it for a fact: I witnessed a friend's battery exploding and setting his Lincoln on fire.) If you're inexperienced or don't feel comfortable working with high-current devices, then hire a professional to do these upgrades and installations.

And please, don't let anyone talk you into doing any of these procedures unless you are experiencing bothersome headlight dimming.

  • Daniel from Chicago

    Posted on 6/14/2015 8:31:38 PM

    2 Quick questions: I have a 2014 Dodge Charger SXT. I plan to install one (1) Orion HCCA154 15" Dual 4 ohm Competition HCCA Series Car Subwoofer w/ a Hifonics MT Olympus Hercules 4K 4,000w Mono Amplifier Competition Car Audio Amp. A.) Will i need to upgrade my car's alternator or can i get away with just installing a capacitor? Second Q: Would I be better off purchasing the ORION HCCA152 15" 4000 Watt Dual 2 Ohm Voice Coil Subwoofer HCCA-152 to go with that AMPLIFIER or will it even make a difference? Your expertise is greatly appreciated. Thank you.

  • Buck Pomerantz from Crutchfield

    Posted on 6/15/2015 2:45:55 PM

    Daniel, Wiring the DVC 2-ohm subwoofer like this diagram will get 2000 watts RMS out of the amp. Wiring the DVC 4-ohm model like this will get 1600 watts RMS. Which do you like better: 1600 or 2000? As for the car's alternator, I'd say you'll probably need an upgrade - the amp will occasionally try to get up to 196 amperes from the system. Adding a capacitor alone will do very little to improve your electrical system's capacity.

  • Tyler

    Posted on 6/17/2015 7:40:10 PM

    I have 2 10" Rockford P2 and 2 12" Rockford P2. The 2 10" are powered by a Rockford r-1000 and the 2 12" are powered by a Rockford r-1200. The 4 subwoofers are in one enclosure, but each subwoofer has its own compartment to where it is sealed off from the other subwoofers so it doesn't ruin them. They are wired correctly and to the correct ohm stability of each amp. Also, all connections are fine as well. My question is concerning that when they are turned up to a certain volume, they will shut off and come right back on when I turn the volume down a little. I know this is because they aren't getting enough volts for that certain note of sound. I am wondering what you suggest to get to prevent this from happening. Sometimes they will shut off when they are not even displacing close to what I know they are capable of. All connections are fine, and both amps have power to them. My power wire is 0 gauge going into a distribution block with 4 gauge going to each amp. I am wondering if you suggest getting a capacitor or the big 3 package? I have thought about ordering both, but didn't know exactly what I need. I am trying to avoid buying a high output alternator because they are so expensive. I really don't care if I can turn the volume up all the way because it can damage the subwoofers, your ears, etc. I am just wondering if either the capacitor, big 3 upgrade, or both would help.

  • Buck Pomerantz from Crutchfield

    Posted on 6/18/2015 11:37:36 AM

    Tyler, Do your headlights dim when the music plays loud? Or are your amplifiers going into protection mode without any light-dimming? Amplifiers go into protection mode for a number of reasons. Insufficient current flow due to a loose ground. Low voltage because of a weak battery. Trying to drive a load below its minimum impedance. Overheating due to being driven too loudly (gain set improperly). So, start by having your battery checked. Then ensure the ground connection is clean and tight. Reset the amp gains. Check the wiring to see if the amps are really driving loads they can handle. Only after all that checks out okay should you move on to the choices of putting in a second battery, doing the big three, or adding a capacitor.

  • justin bresnahan from United States

    Posted on 6/24/2015 8:44:20 AM

    Do you leave the stock wire in place after doing the big 3 upgrade?

  • Buck Pomerantz from Crutchfield

    Posted on 6/24/2015 10:30:15 AM

    Justin, Yes, that is always a good thing to do.

  • Jason from Salt lake city, UT

    Posted on 7/5/2015 3:59:59 AM

    I have 2 jl w7 12 inch with a rockford fosgate amp t2500 and I have 4 15 kicker l7 2 ohms with a zx.11 2500 I do have a stock alternator . I have 2 batteries and one capacitor. My truck struggles to turn on at time I know my amps are using to much power out of the batteries. My question is what should I upgraded first? My battery or alternator. And what are some of the best brands out there ?

  • Buck Pomerantz from Crutchfield

    Posted on 7/6/2015 4:53:39 PM

    Jason, So you're powering your subwoofers with about 4500 watts RMS - that's an enormous draw on any vehicle's electrical system. Do you have an amp for your full-range speakers also? I'm not sure there's any stock system that could support this. Make sure each of those sub amps has its own 1/0-gauge power wire to the battery. Make sure your two batteries are up-to-date and keep their charge. After that, I can only see upgrading your alternator as the solution. You'll have to go to an automobile shop for a recommendation on high-current alternators.

  • joey

    Posted on 7/12/2015 9:46:20 PM

    i have a soundstream goliath 6500 4 mtx 75 12 inch woofers a autotek 1200 watt amp n a power acoustic 2500 watt amp the autotek is running 2 american bass 6.5 n a two rockford f tweets the power acoustic is running 4 6.5 mtx n 2 horns i have a optima yellow top battery under hood and a optima blue top marine batrry in trunk stereo plays for a amount of time then the 6 speakers in front cut off and eventuly the subs and the highs in back just play i have a 150 amp altenator and all power and groind wires are 0 gauge would u suggest uppong the amps on alt or another optims marine or both system is in a 73 impala

  • Nolan from Arizona

    Posted on 7/13/2015 12:22:56 PM

    I will be getting one Fi audio bl12" sub along with a CT sounds 1400.1 amplifier. I will be pushing 1500 watts rms. Anyways I drive a Honda Civic coupe 1.7L with a stock alternator and battery. I have already spent more money than I have and I'm trying to do this part as cheap as I can until I can do it right. I have a friend that is telling me I can get away with just buying a battery and a capacitor. But from all of the reading I've done, it seems like every single person has different opinions on it. If I don't upgrade my alternator and I just get the battery with a capacitor will the battery eventually die? What do you suggest I do?

  • Buck Pomerantz from Crutchfield

    Posted on 7/14/2015 11:23:58 AM

    Joey, If I understand, you have up to 2900 watts RMS going to subs, 150W going to two sets of speakers and 100W going to four more, for a total of 3600 watts RMS. At full power this system would need 522 amps of current. Even if we took into account a duty cycle for music of one-third, that would still mean you'd need 174 amps to run the audio system. Add in what it takes to run your car and you can see that a much larger (and expensive) alternator is called for in your situation.

  • Buck Pomerantz from Crutchfield

    Posted on 7/14/2015 12:09:56 PM

    Nolan, I suggest you wait until after your amplifier and subwoofer are installed, and after you start experiencing headlight dimming before you do any electrical system upgrade. There's no point in preparing to fix something that may not be broken.

  • Michael from Ocala

    Posted on 7/15/2015 9:26:04 AM

    I have (2) 12's DB 2000 4ohms 2000 watts , krank it up fc-1200 battery for the amp and a OE mopar battery for the 2013 jeep grand cherokee laredo, amp (clif design CDX20A 3k to 4k watts) The 12 are dual coil and they were wired in series negative to negative and positive to positive Getting light dimming. it has been over a year since I used the krank it up battery for audio.. 1.) do you think the battery is bad or 2). should I be adding a 10 farad cap.. or would adding another battery by sufficient 3.) or checking the the ground

  • Buck Pomerantz from Crutchfield

    Posted on 7/15/2015 11:58:01 AM

    Michael, The only way to find out if your battery is bad or not is to take it to a battery or auto parts store and have them test it. Making sure your batteries are good and the ground wiring secure are the first steps in eliminating light dimming. If you've already added a second battery and are still having dimming issues, perhaps a capacitor will help. But it sounds like, for the long term, you're going to need a higher output alternator.

  • juancho from nashua nh

    Posted on 7/15/2015 12:46:44 PM

    quick question how would i wire 2 Alpine SWS-12D4 12" Dual-Voice-Coil 4-Ohm Subwoofer to a Rockford Fosgate PRIME R1000-1D its a Single-Channel Monoblock

  • Buck Pomerantz from Crutchfield

    Posted on 7/15/2015 1:27:13 PM

    Juancho, Like this diagram

  • Signar from Kollafjordur

    Posted on 7/21/2015 7:37:34 AM

    Hi. I just bought a new car system. And as it seems, you guys really know your stuff. So I would just like to know if I need a bigger kondensator, and if I really need to do The Big 3. Just whatever I need. With the lowest cost possible, but still get full effeciency from the car sound system, and not screw the electrical stuff up. What I got: Subwoofer 4000 watt (2400 max output). 2x amplifiers 4000 watt each. 1x amplifier 10.000 watt 6x car speakers 1000 watt each. 1x kondensator 2 farad. I think I must get a 4 farad kondensator? I was thinking of using the 10.000 amplifier and 1 amplifier 4000 watt. What do you guys think about this?

  • Buck Pomerantz from Crutchfield

    Posted on 7/21/2015 3:22:38 PM

    Signar, First of all, I suspect those huge power ratings you quote are peak or maximum specifications, which are useless for planning out a sound system. Use RMS ratings only. Secondly, it sounds like you haven't installed this gear yet. I suggest you wait until after it's installed in your vehicle and after you start experiencing headlight dimming before you do any electrical system upgrades. There's no point in preparing to fix something that may not be broken. You may not even need a capacitor (kondensator) at all.

  • alex zakharov from United States

    Posted on 7/29/2015 1:13:49 AM

    Ok...so i have a 2006 Hyundai Tucson. and got a hold of 2 12" sony explod woofers with a sony explod 1200 watt amp. everything was going great. until after about a year or so of blasting..the amp fried...(it was old ish). After that i got a Planet Audio 2400 watt 4 channel amp. and hooked it up to the woofers and it sounds amazing...but after short 4 months or so of blasting..my alternator fried. so i got a new alternator installed..and before i hook up the woofers again, i wanted to ask what would be the best solution for my case...i still dont know much about woofers. as much as i want power...i want my alternator to have as least strain as possible. please help

  • Buck Pomerantz from Crutchfield

    Posted on 7/29/2015 3:53:11 PM

    Alex, You didn't mention experiencing any headlight dimming when the music played before your alternator died, so maybe the amp had nothing to do with it failing. Did you ask your auto repairman what he thinks caused the alternator to fail? It was a 9-10 year old part. If after reconnecting your system you get light-dimming, then you'll know you need an electrical upgrade.

  • Thomas rossiter from Oak forest

    Posted on 7/30/2015 9:22:22 PM

    I have a 2009 Malibu that had a Bose system in and I got a jl 2 channel amp for a pair of jl audio 13 subwoffers and jl inside speakers with separate tweeters and a 400 watt amp hooked up to them hooked up to a clarion head unit with DVD and gps! My head lights dim when turned up loud to bass beat and amp sometimes shuts down and I'm getting crakling sounds from tweeters even when radio is off! 4 gauge wired was used and installed from qualifying installors! What do you think Is wrong?

  • Buck Pomerantz from Crutchfield

    Posted on 7/31/2015 10:56:47 AM

    Thomas, I think you should take your car back to your installer as soon as possible and politely point out the issues and give him a chance to correct any problems or suggest possible solutions.

  • Jeffrey Wright from Corpus christi

    Posted on 8/5/2015 4:27:08 PM

    Pretty cool nice to know some of these things thanks alot..

  • Anthony Baca from Las Cruces New Mexic

    Posted on 8/14/2015 1:25:30 AM

    I'm looking for a high output alternator for my 86 mazda b2000 do you have one that will work

  • Buck Pomerantz from Crutchfield

    Posted on 8/14/2015 12:27:29 PM

    Anthony, Sorry, Crutchfield doesn't sell alternators. You should check with a local auto parts store for that.

  • Noah Latour from Wilson

    Posted on 8/20/2015 1:57:09 AM

    Quick question. I have a 2004 Chevy Silverado 1500 and I'm planning on putting in a orion hcca 15" subwoofer with a 4000 watt amp. If I were to add a second battery for the amp, and then on top of that, a capacitor. So a 15" sub, 4000 watt amp, second battery, and a capacitor. Think my vehicle will handle that pretty well? Amp: Planet Audio AC4000.1D ANARCHY 4000-watts Monoblock Class D 1 Channel 1 Ohm Stable Amplifier Capacitor: Planet Audio PC20F 20 Farad Capacitor Second battery: Kinetik HC600 BLU Series 600-Watt 12-Volt High Current AGM Car Audio Power Cell Battery

  • Buck Pomerantz from Crutchfield

    Posted on 8/20/2015 10:04:02 AM

    Noah, When planning a system you should only consider RMS ratings, never peak specs. That amplifier's advertised ratings are 2000 watts RMS at 2 ohms and 2800 watts RMS at 1 ohm, but in my opinion, judging by its fuse complement, even those figures are exaggerated. I think you should go ahead and install your sub and amp and see if your truck's electrical system can take it before spending more money on a second battery and capacitor.

  • Reuben Perea from Glendale

    Posted on 8/23/2015 7:44:30 PM

    Hello, My name is Reuben and I have a 2004 Acura TSX. I recently put in a 1400 watt Crunch amplifier running all 6 Infinity speakers that came standard in my car. I also have a 2500 watt Hifonic amplifier in my trunk pushing one 12" Rockford Fosgate subwoofer (uncertain of wattage) but now that I'm running both amplifiers all my lights in and out of the car are dimming. How would you recommend I fix this problem?

  • Buck Pomerantz from Crutchfield

    Posted on 8/24/2015 12:52:23 PM

    Reuben, This article is meant to explain to you what steps to go through to help eliminate light-dimming yourself. You start by ensuring that all the power and ground wiring is clean and secure and that the battery is good. Then you'd add products like a Big 3 upgrade kit or a capacitor. Only after that should you look into getting a high-output alternator or a second battery.

  • Colton

    Posted on 8/26/2015 10:53:27 AM

    i have a 2001 subaru outback im gonna put 2 pioneer champion pros in running 1200 rms will i need to get a bigger alternator

  • Buck Pomerantz from Crutchfield

    Posted on 8/26/2015 1:50:31 PM

    Colton, You won't be able to know whether or not you need a high-output alternator until after you install your amplifier and experience light-dimming with music.

  • Zack Delgado from 253TACOMA WA

    Posted on 8/28/2015 8:53:32 AM

    I recently got an Audiopipe APCL-3000.1 class d mono amp and will be running either 3 or 4 alpine typeR 12's dvc 4ohm. Now I have seen the bench test on this amp and it functions a lot better at 16volts now my 2003 f150 supercrew truck along with just about everyone else in Americas car electrical system runs between what 12 and 14 something volts. So my question is, I want to upgrade my charging system to a 16volt system, how do I do that? Is it expensive? What does it entail?. THANX

  • Buck Pomerantz from Crutchfield

    Posted on 8/28/2015 10:45:34 AM

    Zack, Your amplifier may perform better supplied with 16 volts, the ignition system may be unaffected, but your vehicle's onboard computer will probably freak out and fry. Your receiver too. Manufacturers publish specs using inflated voltages so they can claim their products are louder than others. You should ignore such claims.

  • al from San Francisco

    Posted on 8/29/2015 4:53:11 AM

    I have a rough estimate of 2000 rms sound system i want to run off a house battery in the trunk but would also like to replace my start battery so running 2 of the same battery 1 in front and 1 in back with A relay battery isolator how many ah do I need or can u recommend a specific battery thanks

  • Dirondi Johnson from Saint George

    Posted on 8/31/2015 2:39:25 AM

    The total wattage of my system will be about 3300 watts once I add the sun. I have a d2400 up front and a d3400 for the back and a battery isolator. Since only one battery will be discharged at a time due to the isolator, do I absolutely need a better alternator than my 120amp? I do not plan on playing my music with the car off but i was hoping that the isolated can help me get around the alternator change since I will be driving the entire time and charging both while only depleting one for the most part.

  • Buck Pomerantz from Crutchfield

    Posted on 8/31/2015 1:14:17 PM

    Dirondi, If you're still having light-dimming issues even after installing a second battery, then I do think a higher-output alternator might help.

  • Alec Reece from Daytona Beach, Fl

    Posted on 9/1/2015 8:22:21 PM

    I have an Orion HCCA 10 inch sub. Dual 2 ohm voice coils wired in parallel to one ohm. 2000W RMS with 4000W nominal. I want to get an amp that does exactly that (2000Wrms, 4000W nominal.) It is labeled as a 4000W mono class D amp. My stock alternator puts out 150amps. I have not bought it yet in fear that i would have to buy this only for my system to not be able to handle it. I have looked for a high output alternator for my vehicle and cannot seem to find one anywhere. Please let me know your thoughts.

  • Buck Pomerantz from Crutchfield

    Posted on 9/2/2015 10:07:08 AM

    Alec, Without knowing the specific amplifier you're referring to I can't say for sure, but I think bumping 2000 watts RMS will tax any car's electrical system beyond the capacity of the stock alternator. I'm sure there are some car audio dealerships or auto parts stores in your area who can help you find a high-output alternator.

  • Joseph W. from Sacramento

    Posted on 9/7/2015 10:26:06 PM

    So I have had a system in every car Ive owned but nothing over 1000 watts RMS. I have now a 91' Chevy Caprice Classic and I think I want to shoot for 2500 to 3000 RMS. I understand you believe in installing the system first and seeing how it acts but my last system had minor headlight dimming pushing 1000 RMS, sooooo Im pretty sure 2500 RMS will definetly do the same. My question is, should I just go along with what I have been doing and just add a couple capacitors? Or should i go strait to adding a second battery?

  • Buck Pomerantz from Crutchfield

    Posted on 9/8/2015 1:47:43 PM

    Joseph, Adding capacitors and a second battery may help your audio system's power draw for short bursts of music, but for long-term supply, a high-output alternator will work best.

  • rassel from denver

    Posted on 9/9/2015 7:23:53 PM

    Thanks a bunch for this article. I have 2008 Porsche 911Turbo ( Alternator 150amp,2100watts,12volt,70 ah battery...i think) . I plan to install One Orion Hcca 122 12" 2500rms watt@2 ohms & Orion 5000.1D 3600rms@2ohms .plus focal 165KRX3 100rms/each 3 way sys with JL HD600/4 ch amp. I really need to know do I need to change the Alternator or Just add a high performance battery or What? Mono Amp is 3600 rms but my One sub can take 2500rms so I need to set low gain on amp right?its a small car so space is issue too. please please help. thanks in advance .

  • Buck Pomerantz from Crutchfield

    Posted on 9/10/2015 12:14:47 PM

    Rassel, Ordinarily I advise waiting until light-dimming occurs before putting in a fix, but you're talking about trying to get a 3200-watt RMS output from a system in a small car. Even taking into account music's duty-cycle only asking for full power about one-third of the time, this would be asking for about 94 amperes from an electrical system that could supply maybe 75 (one-half the alternator's capacity). A second battery may help a little, but it sounds to me you'll need a higher-output alternator to take care of this large a system.

  • Eric from Houston

    Posted on 9/13/2015 3:07:54 AM

    I have a 2002 Firebird v6 and plan on getting two kicker 10" CVX rated at 800 rms each and plan on getting a kicker 2400W class D monoblock amp rated at 1200rms. Should i go ahead and get the big three upgrade as well as upgrading the alternator?

  • Jon from Clearwater

    Posted on 9/13/2015 8:38:29 PM

    Hi, I have a 2001 Toyota Corolla with the stock 80A alternator. Currently, I'm running a Jensen 75w x 4 4 channel, Class AB amp to 4 Kicker KS Series speakers, each rated at 100W RMS. I plan on getting 2 10" Rockford subs rated at a combined 300W RMS, and pairing that with a Class AB 250W RMS Rockford amp. I'm worried on whether or not adding the subs & mono amp to my stock system will cause problems. If so, what kind of problems? I'm leaning towards a High Output Alternator, something like 150A or so. Any help would be appreciated!

  • Buck Pomerantz from Crutchfield

    Posted on 9/14/2015 1:09:39 PM

    Eric and Jon, I don't think either of you will have a problem adding your gear to your factory systems. However, if you like to play music with loud and long bass bursts that suck up a lot of power, then you may find you will need to upgrade your wiring, battery, or alternator.

  • Graham from Sylva

    Posted on 9/18/2015 6:22:38 PM

    I currently have a 96 landcruiser with a stock alternator putting out around 80 amps running a 75x4 mb quart and a kicker 600.1 running a jl w6 and i am considering adding 2 more jl w3 8s I found a rockford Fosgate that puts out around 500 watts to a single channel should i consider upgrading the big three? I would like to avoid buying a new alternator if possible because they aren't exactly cheap

  • Buck Pomerantz from Crutchfield

    Posted on 9/19/2015 10:23:07 AM

    Graham, The Big Three improves power flow, but does not add power to an electrical system that needs upgrading. The only ways to add power are putting in a second battery and getting a high-output alternator.

  • Aedan from magnolia, de

    Posted on 9/25/2015 8:46:16 AM

    i have a 2010 Toyota Corolla with stock alt(100a) and battery. I just bought a new batt. My speakers total 200-250rms and I have a JL audio(50x4) amp for them. Then I have two 12" rockford p2s totaling 800RMS and a hifonics Brutus 1100.1d amp... When I had the hifonics wired @4ohms I had no light dimming but now I have it @1ohm and it's horrible... I've checked all my wires and grounds, so I know my next step is the "big 3"... I was just wondering if you thought the big 3 would stop the dimming, or if I will have to buy a 2nd battery too. (Because if so, I'd rather just order everything online at once)... Just looking for a professional opinion. Thanks in advance!

  • Buck Pomerantz from Crutchfield

    Posted on 9/27/2015 11:39:13 AM

    Aedan, I wouldn't have thought those amplifiers could overwhelm your vehicle's electrical system. I'd recheck the wiring and especially check your battery to see if it needs servicing or replacing. While doing the Big Three improves current flow, and that's always a good thing, the best way to provide more power to your system is with a second battery or a high-output alternator.

  • Wyatt Black from gastonia

    Posted on 9/29/2015 8:48:47 AM

    I have a 2001 tahoe I have 1000 watt kenwood kac 929 i believe and 2 12 inch subs. When playing at normal levels everything is fine but when i turn it up my headlights dim and my dash lights dim. Also my amperage guage is car goes back and forth with the neat from 14 all the way to 9. When ot starts to dip down my amp goes into protection mode. Ik my battery is more then 4 years old. Do you believe it is battery because i know alot people which same amount of power and 1000 watt amps that dont have this problem with stock altinators

  • Buck Pomerantz from Crutchfield

    Posted on 9/29/2015 2:23:27 PM

    Wyatt, The Kenwood KAC-929 amp can put out up to 460 watts RMS when bridged to a 4-ohm load, which shouldn't distress your electrical system. But if your vehicle's voltage gauge (not amperage) shows the voltage drop below 10 volts when attempting to play music, something's wrong. Having the battery checked is a starting point. It sounds to me that your subs may be wired so that the amp has been presented with an impedance it can't handle and protects itself rather than burn up.

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