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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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Headlights can dim when you need more power

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 three wiring upgrade kit

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 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 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.

  • Ryan from Rockford

    Posted on 10/12/2015 10:24:45 PM

    Hi. I was wondering if I should go with 4ga wire or 0ga wire with my hifonics brx 1100.1 it's 800w rms @ 2ohm a 1100w rms @ 1ohm. I have it wires at 2 ohm on a kicker 15 inch l7.

  • Buck Pomerantz from Crutchfield

    Posted on 10/13/2015 1:14:58 PM

    Ryan, That amplifier calls for 4-gauge power and ground wiring.

  • Mitch from Cape Town

    Posted on 10/15/2015 8:48:11 PM

    I have a Citroen C2 with 2x 10" dVC 40ohmTarga 6000watt subwoofers and a 11000watt Targa MonoBlock amplifier and a 500watt 4channel amp for my mids. Any volume above 12 and my headlights get a serious dim. Mind you its an old model car. Upgrade battery and alternator i suppose? What you think?

  • Buck Pomerantz from Crutchfield

    Posted on 10/16/2015 12:47:32 PM

    Mitch, The first thing you should do is check to see if the power and ground cables for your amplifiers are adequate. I'm not familiar with that brand of amp, but I suspect those enormous power specs you quote are peak ratings, which are useless for planning a system. Find out your amplifiers' total RMS power rating and check out this article to see if your cables are large enough. After that, you could recheck the wiring again, check the battery, upgrade your wiring, replace the alternator, or add a second battery. Unfortunately there's no one correct solution to this problem, especially with a large system in a small vehicle.

  • Mitch from Cape Town

    Posted on 10/18/2015 4:15:11 AM

    Hi sorry. In RMS each sub is 1000w RMS and the monoblock amp is 2000w RMS. Ground cables are all stable. Everything is good until i play my music above 12, thats without me tampering with the parametric. Car is rather small and considering removing the back seats to make room for another battery. Thanx for the feed back though. Much appreciated

  • Swampy from timbuktoo

    Posted on 10/26/2015 8:39:10 AM

    I am running a Merlin Meam 3000 mono block 1 ohm stable. To a Merlin 12" M7 1100rms in parallel. I do some sound demo with the vehicle but rarely since merlin is no longer manufactured. The thing is I had zero dimming issues until i ran heavy load on the system with headlights and such which caused the primary front harness short poof caught fire. 90amp OEM alt, after the short i am seeing dimming which i had minor/zero issues with before. Though the amperage is low still costly, i was thinking of upgrading the positive and chassis ground on the alternator to 1 gauge all around would you recommend this or any other suggestions.

  • Buck Pomerantz from Crutchfield

    Posted on 10/26/2015 3:57:36 PM

    Swampy, Before upgrading your alternator's wiring, you need to address why your amplifier wiring caught fire. Just running an amplifier hard should not cause a short circuit. Check your wiring for loose connections or stray conductors. Perhaps the power wire and fuse aren't appropriate for the amp. I'm not familiar with that amp, but according to what I can find out online about it, it needs 2-gauge power and ground wires with a 125- or 150-amp inline fuse near the battery.

  • Swampy from timbuktoo

    Posted on 10/27/2015 8:30:51 AM

    Actually the amp wire was not the issue. I didn't state that clearly I appologise. It was the OEM front ends wire bundle that controls the headlights, turn signals, and clearance lights. Apparently the draw as so severe with the heavy draw of the amp and sub that it caused a low voltage situation on the OEM wire bundle, basically starved the front end of the vehicles electrical connections. I am running TSpec 2ga power and ground wire to the amp with a 250 fuse. Was considering doing the alt, battery power lines into 2ga, all connections at the alt and ground are secure, it is a older car with a lot of electronics that are 25 years out dated by current vehicle designs. The amp has 4 40 amp fuses, it as well is not a efficient amp, mostly just a sledge hammer power amp versus lets say like a ARC 1000 amp. The question is since the working theory was a power draw/starvation on the OEM electrical system issue, would the three new 2ga wiring be enough or should i also put in a cap/battery as well? Or any other suggestions would be greatly appreciated.

  • Buck Pomerantz from Crutchfield

    Posted on 10/27/2015 11:40:00 AM

    Swampy, If your power cable were to suffer a short, the 2-gauge wire would melt, burn, and possibly set your vehicle on fire before the 250-amp fuse would blow. For your safety, you should replace that fuse with a 200-, 150-, or even a 125-amp fuse. If, after confirming that your battery is fully functional and that all wiring and grounds are secure and tight, you still experience light-dimming, I suggest looking into adding a second battery or a high-output alternator. A Big Three upgrade or adding a capacitor wouldn't hurt, but by themselves probably won't do much to alleviate the issue.

  • Swampy from timbuktoo

    Posted on 10/28/2015 6:26:40 AM

    @Buck Pomerantz: Thank you for your insight. It is greatly appreciated. You verified precisely what the master installer at my employer stated as well. I will look into the high output alternator. Thanks again.

  • James from Miami

    Posted on 11/1/2015 4:58:56 PM

    I'm planning to get a kicker dual 12 inch CompR and a kicker DXA1000.1 which in total will be 1000 rms , do I need to do any upgrades ? I'm told that I'm fine with a capacitor . I have a 2015 Sentra

  • Buck Pomerantz from Crutchfield

    Posted on 11/2/2015 2:09:10 PM

    James, You won't know if you need an electrical upgrade until after installing your gear properly you experience light-dimming when the music hits hard. Only then should you try and solve the issue by installing a capacitor.

  • James from Miami

    Posted on 11/2/2015 9:07:10 PM

    Is there any calculations I can make ? So I won't have to buy the big 3 or a high put alternator ? With my 2015 Sentra I have a 600 rms system that's the kicker comps and kicker amp with the 2 farad capacitor in which it works perfectly fine , but I asked several people from crutchfield that I should be fine with a capacitor if I have a system of 1000 rms watts , so it should be 400 rms watts more Imma add to my upgrade if I was to get the dual 12 inch compr , I know it's a lot of power so the only way to know for sure is the dimming lights ? And if that happens a capacitor should help and I'm set ? I just wanna buy the loaded enclosure and the dxa1000.1 amp without having to worry of buying the big 3 or high put alternator since I'm in a budget and I don't want to damage my alternator either so yeah . Thank you for replying for my last question too

  • David Prillaman from Newport News

    Posted on 11/2/2015 9:29:42 PM

    Buck, i have two jbl w12's. Dvc 6ohm 4000w 750w rms. I am planning to wire the two parallel which will make it 1.5 ohm as i read on their site. I have been asking around local audio store and it seems nobody has any similar views. One guy said 6 ohms is odd and that if i dont get the right amp i could fry my subs. What should my amp specs be and will my 88 bronco be able to handle them? Thanks -Dave

  • Buck Pomerantz from Crutchfield

    Posted on 11/3/2015 1:19:36 PM

    James, First, calculate your amplifier's current draw: take the total RMS wattage times 1.25 (inverse of Class D amplifier efficiency); divide by 13.8 volts (running car); equals the current draw in amperes That Kicker amplifier should be able to draw up to 91 amperes of current at maximum output. How often that occurs depends on the music you listen to. EDM, dub, and rap use more "duty cycle" time on bass hits than other forms of music like classic rock or country. For most applications, you can figure one-third of the maximum current draw will be needed on a constant basis. In your 1000-watt amplifier example, count on needing about 30 amperes of constant current. You then estimate to see if that much power is available from your stock electrical system by dividing the current rating (amperes or "amps") of your alternator by 2. For example, if your Sentra has an 80-amp alternator, 40 amps are available for aftermarket equipment and your 30-amp system demand will be easily served.

  • Buck Pomerantz from Crutchfield

    Posted on 11/3/2015 1:49:13 PM

    David, To power those subs, you should look for an amplifier that can put out from 1200 to 2500 watts RMS at 1 ohm. A good choice would be a Rockford Fosgate T1500-1bdCP, which would be able to put out 1500 watts RMS to your 1.5-ohm load - perfect for those subs.

  • Michael Powell from Whippany

    Posted on 11/5/2015 1:12:54 AM

    Hi, I have an 03 trailblazer . I running two jl audio 10w6 subs and 2 pairs of component speakers, top dash speakers . 3 jl audio slash amps .. 1200/1 v3 and 2 450/4 v1... I installed a 250 amp alternator and the big 3 kit.. I still get some head light dim but my bigger concern is when I play music with heavy bass the 2 450/4 amps cut out for a few seconds than come back on.. do you suggest a second battery is needed or other options ? Thanks - Mike

  • Buck Pomerantz from Crutchfield

    Posted on 11/5/2015 12:49:31 PM

    Mike, After checking that the power wiring (you should be running 1/0-gauge wire from the battery to a distribution block) and ground connections are secure, and that your battery holds its charge correctly, then you may find that a second battery by the amplifiers will eliminate those electrical issues.

  • Morgen from Milton

    Posted on 11/19/2015 12:59:38 AM

    Thank you for the excellent write up, I am having issues getting ring terminals to do the big three. My alternator is a 200 amp ford 6g styled. I am having a hard time finding terminals that will fit the alternator and still support 2 awg wire. Do you have any suggestions on doing the big three on a ford ranger?

  • Buck Pomerantz from Crutchfield

    Posted on 11/19/2015 9:33:02 AM

    Morgen, I've forwarded your questions to Crutchfield's Sales Advisor Team, and a member will get in touch with you by email to offer suggestions and help you choose the right gear for you and your vehicle. For immediate help, you can contact them via phone or chat.

  • Adam from Louisiana

    Posted on 11/20/2015 9:21:07 PM

    Good Day I recently purchased Alpine SPR 60C 330watts max @110RMS per speaker for Front and Rear Door Speakers Alpine SPR 60 Coaxial 2-way @100watts RMS per speaker with an Alpine PDX F4 4channel amp at 400watts RMS. I also purchased a single Alpine SWR-12D4 subwoofer 3000watts max power @1000watts RMS along with a Hifonics Brutus 1500W Mono Amp. I haven't installed the system as yet because i was wondering if I should upgrade my Big 3 wiring and/or add a capacitor/battery to my car. I don't want my headlights and lights to be dimming if i install this system.

  • Buck Pomerantz from Crutchfield

    Posted on 11/23/2015 1:58:46 PM

    Adam, Not knowing the rating of your vehicle's alternator makes it impossible to predict whether that aftermarket system will strain it or not. If I correctly understand what amplifiers you have and how you intend to hook them up, they are capable of putting out a total of 1300 watts RMS when playing together at their loudest level. At that point, they would be trying to draw 118 amperes from the electrical system. Fortunately music doesn't demand full power all the time - we figure on a "duty-cycle" for music of one-third. So, in your case, the system would need about 39 amperes all the time. If your car's alternator is rated for 80-amps or more, it will probably handle the system okay. If your alternator is smaller than that, you'll probably need to upgrade the electrical system with a second battery, a capacitor, or the Big Three.

  • Brandon from Pensacola

    Posted on 12/2/2015 1:53:36 PM

    Hey I see you actually respond to people and I was wondering if you could help me out. In my '09 Nissan Altima, I have 2 amps: a class D Hifonics ZRX 3000.1 and a Hifonics 1400 4-channel amp. The sub is a Kicker L7 12 inch. Head unit is JVC AV61BT and I replaced the door speakers with Pioneers that can handle more than stock speakers. I replaced the battery with a dry cell battery But for whatever reason, my battery is down to 33% and I've only had it for about 6 months. I've been told that my alternator can't keep up with recharging the battery. But they also said that replacing the alternator wouldnt be feasible. Is that true? What should I do?

  • Buck Pomerantz from Crutchfield

    Posted on 12/9/2015 5:00:21 PM

    Brandon, Your first step would be to find out if your dry cell battery is appropriate for automotive use and check that it's working properly. Another thing to do would be for you to disconnect your audio system's power (pull the fuse) and see if the alternator can then charge the battery fully. If you really can't upgrade the alternator (I'd get a second opinion on that) then you may have to add a second battery or even a second alternator in order to successfully run your audio system.

  • Dillon Jones from La Verne

    Posted on 12/10/2015 9:48:01 PM

    Hey Buck, I'm thoroughly impressed and give my highest respect toward your devotion to answering everybody's questions. You make Crutchfield look good.

  • Ronald from Portland

    Posted on 12/14/2015 2:58:35 PM

    I have a 99 civic coupe and I'm putting two 12" re audio dvc 4 ohm 750w rms each to a polk audio pd1000.1 which at 1ohm will put out 1200rms so my system will be about 1200rms I am going to do the big three and wire all thick gauge wire what else will I need ? Or what all should I need

  • Buck Pomerantz from Crutchfield

    Posted on 12/15/2015 10:17:00 AM

    Ronald, You don't need to do anything beyond installing your gear and rocking out. If you then experience headlight-dimming when the bass hits hard, then you should proceed through the steps this article lays out to solve that issue. You shouldn't try to solve a problem that doesn't yet exist.

  • David from Slidell,LA

    Posted on 12/20/2015 12:33:35 PM

    I have 12" Mtx with 400w rms I have its powered by a 1200w kicker mono class d amp with its powered with 4g wire and 16g speaker wire. My alternator is around 120-130 amps and the lights dim slightly when the volume is around max. Should I retune the amp or looking in to a capacitor

  • Buck Pomerantz from Crutchfield

    Posted on 12/21/2015 2:50:22 PM

    David, Like this article describes, start by checking the ground and power connections and the battery. After confirming that they are all good, then you can proceed by adding a capacitor, or a battery, doing the Big Three, or upgrading the alternator.

  • Shay from Telford

    Posted on 12/26/2015 2:01:19 PM

    Hello. I have a question for you. I have 2 JL 1000/1 amps and 2 JL 300/4 amps. The 4 channel amps will have their channels bridged to power my 8 6.5 inch alpine type R speakers while my 2 JL 1000/1 amps will power my 2 12inch JLW7's. I am currently waiting for this alternator to come in the mail and have already upgraded my battery, chassis and alternator ground wires to 0 gauge. I also plan on running the ground wires for the amps back up to the negative post on the battery to help transfer more power from the front of the vehicle to the rear (JL and a competition stereo experts advice). My question for you is, what kind of spare battery would be best and how many should I get? Should I get a capacitor as well? Anything else I should look into before I have my system installed? Thank you for your response in advance. Merry Christmas!!

  • Buck Pomerantz from Crutchfield

    Posted on 12/28/2015 12:18:53 PM

    Shay, You didn't say how large your new alternator will be so it's impossible to say whether or not those amplifiers might overwhelm it after they're all installed. I suggest you wait until your system is installed and exhibits light-dimming before adding a second battery or a capacitor.

  • spencer

    Posted on 1/2/2016 3:39:34 PM

    I currently have 2, 12 inch subs. They use 1000 watts rms of power, was thinking of getting door speakers, and adding another 500 watts rms to my system, i think i will need some sort of upgrade, which is the best option between 2nd battery, better wires or new alternator, i have a 2003 mazda tribute

  • Buck Pomerantz from Crutchfield

    Posted on 1/4/2016 10:21:21 AM

    Spencer, If, after installing all your amplifiers, you experience light-dimming when your music hits, you can go through the steps delineated in the article to solve it. Check the wiring, then add a battery or high-output alternator if the problem persists.

  • Jesus Rojas from Estes Park

    Posted on 1/5/2016 10:42:48 PM

    Hi, my battery died today and after a jump start it seemed as the battery didn't have enough juice. I noticed the positive battery terminal was loose and when tightening it broke. Replaced the battery terminal and had to jumpstart the car every time to start the car. I have an aftermarket stereo that does not have a power button so the screen stays completely on until the cars turned off. I also have a kicker sound system with one kicker amplifier 1200 watts on the 2004 Acura TSX. I have experienced lights dimming when the music is playing. I only play the music when the car is on. I replaced the battery. And car works like new. I disconnected the subwoofer for now. Do you think I should make some electrical upgrades so that the cars power can work well with the sound system and and after market stereo? What's the best option for dimming lights?

  • Buck Pomerantz from Crutchfield

    Posted on 1/6/2016 1:18:25 PM

    Jesus, As far as I know, all aftermarket receivers have an on/off button, often marked as a "source" button. If yours doesn't work, it may mean that the receiver's constant power and switched power wires were mixed up during installation. This could be a reason the battery drained. If everything's hooked up correctly, and you have a new battery, and still experience light-dimming, then you should follow the steps in the article by re-checking or upgrading the wiring, adding a capacitor or second battery, or getting a high-output alternator.

  • Cody from Naples

    Posted on 1/11/2016 11:24:54 AM

    i have a 1999 Chevy truck with a V8 motor so the alternator puts out about 120 amps, my friend sold me his 18" subs with a 3,500 watt amp. How can I get these fully powered without the amp going into protection mode? How big of an alternator should I go with? Is 270 amps enough or do i need 300 amps? I also have a second battery tray in the hood compartment, can i just get two new yellow top optimas and put both batteries up front or does the second need to be by the amp? Do I need the big 3 wiring kit?

  • Buck Pomerantz from Crutchfield

    Posted on 1/11/2016 3:41:53 PM

    Cody, I suspect that 3,500 watt spec is a peak, not an RMS rating, and therefore useless for planning out a system. Most car electrical systems offer about 50% of their alternator's power for non-automotive, aftermarket devices. This means that you may have up to 60 amperes available, which would easily handle a 450 watts RMS Class AB amplifier or a 600 watts RMS Class D amp. Most stock electrical systems can take a 750 or even a 1000 watts RMS amp without an upgrade because the amp doesn't try to pull full power all the time when playing music. Electricity travels so quickly that it really doesn't matter too much where you mount a second battery, although most people feel that they do the most good near to the amp that uses the most power. I'd wait to do the Big Three until I see evidence of poor current flow, like headlight-dimming.

  • Kenny from Camino

    Posted on 1/17/2016 10:01:42 PM

    Hello, So I was curious if I need any electrical upgrades at all based on my situation. My setup: Napa legend premium battery 4 ga. amp wiring kit going to 1000W RMS 8 ga. amp wiring kit going to 45W X 4 RMS The 1000W RMS amp powers a 15" 1000W The 45W X 4 amp powers 2-6x9's & 2-6 1/2 My situation: So everything that I described above sounds and works amazingly except for the times when I really want to crank the gain up on my 1000W amp to power the 15" sub louder and before I can even hear distortion coming from the sub (it's a very strong well built NVX sub) it sounds like the amp & sub gets starved of power, likes its hungry for more but can't get it. Also at that same time that's happening the lights do dim very slightly even with the car running. So that's my situation and my question is do I need to do anything electrical wise to be able to crank the gain on my amp when I feel like it and have it not seem like it's hungry for more power? Just to clarify, it's a NVX 1000W RMS amp and a NVX 1000W RMS 15" sub. Thanks in advance!

  • Buck Pomerantz from Crutchfield

    Posted on 1/18/2016 10:09:01 AM

    Kenny, I can find no specific specs on those amplifiers, but if the RMS ratings you quote are correct, the power wiring needs upgrading. The two amplifiers together will require a 1/0-gauge wire from battery to distribution block. And the 1000-watt amp will need 4-gauge power and ground, while the 4-channel can do with 8-gauge or even 10-gauge, for the short runs. This upgrade will allow the amps to draw more power from the electrical system than they do now, so you may experience even more light-dimming. Then you can go through the steps outlined in the article: Big Three, second battery, capacitor, or high-output alternator.

  • Jason Ledbetter from Lubbock Texas

    Posted on 1/25/2016 3:01:57 AM

    I have a question. I have a 2007 Dodge Grand Caravan sxt? with the 3.8 v6. 6 month old battery. My door and dash speakers are factory, un-amped. I had some subwoofers installed a few months ago, and my headlights dim constantly. Amp is American Bass Sq 1550? I believe. The subs are cerwin vega he'd 10s. Rms is like 150 a piece so I would think this is a very mild power subwoofer system, although they can get pretty loud in my van. Even at lower volumes, with mild bass hits, the lights dim significantly and it's driving me nuts and it can't be good for my van. I am a bass head of sorts, and want to get louder and heavier bass in the near future but can't even listen to it now cause I look like a goofus with diminished headlights. The shop that installed them keeps talking about capiciters and batteries. I don't want caps and extra batteries for a 300 rms system. That sounds rediculous to me at 400 bucks for something I don't see really working. I'm thinking big three wiring, and high output alternator. Got a quote for 300.00 for a 170 amp highoutput, and 400.00 for a 250 amp. Both spec at full output at 1800-2000 rpms with a 2 year warranty. Am I thinking right? Or am I thinking non-sense? And listen to the capiciters talk. Thanks a bunch!

  • Buck Pomerantz from Crutchfield

    Posted on 1/25/2016 2:26:17 PM

    Jason, It doesn't matter what wattage ratings your subs have, it's your amplifier's current draw that will affect the electrical system. If your amp is actually an SQ1150M, then it should not outdraw your car's electrical system. If you're unsatisfied with the way your installers are handling the situation, you can either take it to another installer or check out the system yourself. Start, like this article say, with the power and ground wiring, making sure everything is tight, secure, and with no loose strands or paint interfering with current flow. Even a 6-month old battery could have problems, so don't forget to have that checked as well.

  • Joseph Patrick from

    Posted on 2/1/2016 2:02:45 PM

    07 tahoe, jbl gto 24001 amp on subs, amp cuts out at high power. Amp has dual 0 gauge to battery with 300amp fuse on each cable. I have carquest AGM(all glass mat) yellow top battery.

  • Buck Pomerantz from Crutchfield

    Posted on 2/1/2016 4:47:07 PM

    Joseph, This article is supposed to help troubleshoot light-dimming, but it sounds like your amp cuts out for similar reasons - 2400 watts RMS is a lot of power for any vehicle's electrical system to try and support. If you've already gone through all the steps this article lays out, starting with checking all power and ground cable connections, then you may need to install a second battery or a new high-output alternator.

  • Brian from Seattle

    Posted on 2/2/2016 10:59:39 AM


  • Buck Pomerantz from Crutchfield

    Posted on 2/2/2016 1:58:45 PM

    Brian, Before trading your DVC 2-ohm sub away, you may want to try wiring it to the amp like this and see if that doesn't tame your current draw a bit. It will be difficult with that powerful amplifier, but if you set the gain low enough it may not overwhelm your car's electrical system anymore. If that doesn't help, you may need to get a second battery or a new high-output alternator in order to run that amplifier.

  • Francisco from National City

    Posted on 2/4/2016 10:10:41 AM

    I was having issues with light dimming so I upgraded to a HO alternator but now my audio cuts of for about 2-3 Seconds then comes back, its always when I accelerate from a stop. My question is do I need a big 3 upgrade to help fix the problem? Or do I need a secondary battery? Or both?? Or should I just add a fuse to my existing electrical system (alternator to battery line)?? I have 1 12" kicker L7 dual 2ohm, with Rockford Fosgate 1000.1 Infinty kappa component speakers in front and infinity 2 ways in back, with Kenwood KAC-8452 800w 4ch.

  • Buck Pomerantz from Crutchfield

    Posted on 2/4/2016 4:10:37 PM

    Francisco, It sounds like when you're accelerating, the HO alternator sends out too much voltage for your amplifiers and they cut out for protection. A Big Three, additional fusing, or a second battery probably won't solve this issue. I suggest taking your vehicle in to whoever installed the new alternator, explain the problem, and ask them to test it to see if additional circuitry is needed to regulate the alternator's output voltage.

  • storm eiserman from belleview

    Posted on 2/7/2016 1:24:18 PM

    Hi, i have a few questions.. i have an 87 caprise classic.. i have 2 12" jl w3s running on a jl 1000v2 and i have a tma 400 4 channel runnin 4 6x9s. The batter i have is an optima yellow top. My problem is that my headlights dim a good bit when im at idle.. i been lookin at gettin a 220 amp alternator but its a one wire that can be ran with the 3 wire setup.. what kinda upgrades should i do to keep my system fully charged at all times

  • Buck Pomerantz from Crutchfield

    Posted on 2/8/2016 12:45:36 PM

    Storm, If your headlights dim along with your music when idling but not when running, you will probably benefit better by adding a capacitor or a second battery than with upgrading the alternator. A high-output alternator doesn't produce much more current than a stock alternator at idling speed anyway.

  • Derrick from Houston

    Posted on 2/22/2016 10:29:01 PM

    Hello, I plan to run 1 sundown 8" x8 subwoofer with 750 rms at 1 ohm, and an amp that powers 750 rms at 1 ohm... I already have 0 gauge power wire running from battery to rear, would I need a capacitor or HO alternator for this setup?Thanks!

  • Buck Pomerantz from Crutchfield

    Posted on 2/23/2016 12:45:58 PM

    Derrick, It would probably be best if you wait until after your amp is installed to see if your electrical system needs upgrading with a capacitor or HO alternator. Most vehicles will handle a 750 watts RMS amplifier without needing any reinforcement.

  • Joe H from Preston

    Posted on 2/26/2016 5:29:27 PM

    Hi, I have a 400W RMS subwoofer pushed by a 450W RMS amplifier. I was going to also wire my 4 aftermarket door speakers to an amp to push 50W RMS to each speaker but my headlights are already dimming when I turn up the amp a little. My speakers start to distort just below the volume I would like. This is my reason for adding the 4 channel amplifier. I also have a 2 Farad capacitor to the amp that powers the sub but it didn't seem to help that much. I've seen voltages up to 15.5V; I'm not sure what that means. Usually it will be around 14.5V until I turn the engine off. My question is, what would be the best thing to do in my situation to stop the headlights dimming so that I can comfortably add the second amplifier to power my speakers. Thanks

  • Buck Pomerantz from Crutchfield

    Posted on 2/29/2016 12:26:54 PM

    Joe, A 450 watts RMS amplifier wouldn't ordinarily cause light-dimming unless the car's alternator was very small or the amp's wiring needed a repair or upgrade. I'd check your battery and wiring first, like this article says, and see if that eliminates the problem. If you bought your gear at Crutchfield, you could call Tech Support for free help troubleshooting your system. Their toll-free number is on your invoice. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Click on this link for details.

  • Jay from Phoenix

    Posted on 3/7/2016 10:36:08 AM

    I have a 2011 Honda Accord , I will be running two- amps Sundown SCV-2000d and An old Rockford fosgate 450.4 I'm also running an American Bass XFL 1244 rated 1000RMS 2000 Max right now at this moment I cant afford an HO alternator but I could probably by two deep cycle batteries .. would this be sufficient without encountering any issues at least for a while ?

  • Buck Pomerantz from Crutchfield

    Posted on 3/7/2016 11:42:35 AM

    Jay, There's really no way of knowing whether or not a specific addition will solve a problem that doesn't yet exist. You may find that those amplifiers won't tax your car's electrical system. But if your lights do dim on big bass hits, adding a second battery will certainly help.

  • Cristian G from San Marcos TX

    Posted on 3/12/2016 11:43:03 AM

    I have a 2014 Volkswagen jetta tdi. I do not have the fender audio package nor the CD changer. I believe my alternator is rated at 140 but I'm not positive on that. I plan to install a kenwood KDC 9106D amp (I believe this is 1000 rms) with two jl 12'' w3v4 subs (I believe these are 500 rms each). My question is can my stock alternator handle the draw from my subs without impeding on my vehicles electrical system? Do you recommend getting a ho alternator? Or possibly performing the big three? Please share your thoughts. Thank you, -Cristian

  • Buck Pomerantz from Crutchfield

    Posted on 3/14/2016 3:21:46 PM

    Christian, If you play continuous bass tones or bass-heavy EDM, you'd probably need to implement some of the suggestions this article makes to alleviate headlight-dimming. But if you're just listening to music, you may find you don't need any electrical upgrades at all. On average, musical programming demands maximum power only for about one-third of the time. What this means in your case is that the amplifier may try and draw 90 amps from the car's electrical system, but only for the small amount of time it takes for the bass note to play. It would probably be best if you wait until after your amp is installed to see if your electrical system needs upgrading or not.

  • chris howell from Oakridge

    Posted on 3/23/2016 2:43:11 PM

    Ive got a 2001 dakota that iv installed a 250 amp alternator pioneer head unit 1000 watt soundstorm 2 ch amplifier a 2 farade capacitor and a single infinity 8 in sub. The only thing my amp is hooked up to is my sub. Every time my bass hits if I have the sound turned up the head unit dies. I haven't noticed any head light dim what do you think would be causing the problem

  • Buck Pomerantz from Crutchfield

    Posted on 3/23/2016 3:32:52 PM

    Chris, It sounds to me that your receiver powering off on bass hits could be due to loose power or ground wiring being shaken by the bass vibrations. Check the wiring first - that amplifier shouldn't stress your electrical system at all. If you bought your amp from Crutchfield, you could call Tech Support for free help troubleshooting your system. Their toll-free number would be on your invoice. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Click on this link for details.

  • Dev from Silver Springs

    Posted on 4/12/2016 3:12:55 PM

    I have a 2009 Nissan Sentra with a stock 110 Amp Alt. I had a 2000w rms amp @ 1 ohm and a 100w rms X 4 @ 4 ohm amp hooked up, and experienced voltage drops into the low 11's. Since then, upgraded to an AGM battery and also did the big 3. I removed my sub amp and only ran the interior speakers for a while, and my voltage never dropped below 14.2. I have a deka group 31 agm I can run in parallel to my starting battery, and then run my subs, but I'm not sure if that will strain my alternator too much.

  • Rafal from Barnsley

    Posted on 4/28/2016 4:47:09 PM

    Hi could you help me out, ive got a mono amp which produces 600rms at 2 ohm and sub 600 rms which is dvc and have 4 ohm independence what would be the best connection?

  • Buck Pomerantz from Crutchfield

    Posted on 4/29/2016 11:12:35 AM

    Rafal, A DVC 4-ohm sub normally gets wired to a mono amp like this diagram.

  • Charles from long beach

    Posted on 5/24/2016 5:02:06 PM

    Hi Buck, heres my system. 1997 mazda miata (i think it has a 60A alternator stock!) running a pioneer DEH-P4200UB headunit which is driving 4 pyle 3.5" coaxial headrest speakers, a pioneer GM-D1004 amp (in 2x90w config) powering my polk audio DB 6501 door speakers. i have 4 dayton TT25-16 bass shakers installed in my seat powered by a BOSS RT1002 putting out 2x25w. i have a pioneer 10" sub in a sealed box (TS-W256C) powered by nanostream PN1-450D putting out maybe 250w. I have upgraded the lights, stock is 55w low beam 60w high, mine are 60w low, 100w high. added oem foglights that are 55w each, but have 100w bulbs sitting on counter. my system started making a high pitch whine, rpm dependent when i added the bass shakers, ive started improving the grounds, but so far no improvement. the battery is in the trunk and very close to the bass amps. planning on adding a ground cable from battery to chassis by just adding jumper cables and seeing if that helps. same plan for the engine ground. but the cable from the alternator to the battery is likely more work than im willing to invest. the other night i was running the system hard w/ the lights on, it started making crackling distortion sounds, i turned the lights off and turned the volume down a bit and the distortion disappeared. i fear my alternator was struggling , and my battery is quite small and puny, and not new. i want to add the dayton RSS265HO-44, amp at 450w@2R, but am afraid my car cant handle it. HE

  • Buck Pomerantz from Crutchfield

    Posted on 5/25/2016 1:58:50 PM

    Charles, You sure do have a lot of electrical equipment in that little car, it's no surprise there's some noise and distortion. If you bought any of your gear from Crutchfield, you could call Tech Support for free help troubleshooting your system. Their toll-free number would be on your invoice. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Click on this link for details.