yeah what he said
The real problem isn't the lights dimming, some people even think it looks cool. The real problem is the voltage drop & repeated overloading of the alternator, not to mention modern computer controlled everything, which doesn't like the varying voltage, the spikes & dips.
I can't tell you how many systems have been installed, only to need a new alternator within a month or so. This is actually common, especially if your working with a car that has had it's alternator in service for 5 years or more. The main goal here is to absorb the dips & spikes, the headlights dimming are only a symptom of the real problem.
an amplifier instantaniously pulling up to 150 amps or much more in some cases, from your battery for a peak is almost as severe as intermitantly shorting the terminals. This will not only overload the alternator, but can also screw with ecm's, bcm's, air suspension and/or suspension controls, not to mention a whole host of other electrical systems in a vehicle.
most of these systems are already being taxed by the fact that they are used in a mobile unstable environment in the first place, & most have been designed to live under these conditions, but add this much more stress & problems can & do occur. This is the main reason that automotive computer systems use say a 5v reference for sensors & such, because they can regulate it & attempt to maintain this constant voltage much more reliably than if they tried to run these systems at full battery voltage, which can easily vary by over 2 volts up or down depending on loads & usage.
when you have a computer on board that is sending out a 5v reference to a sensor it is comparing that reference to what it gets back on the output. if it sees a return of say 1.13v it tells the computer what the condition is of what's being monitored by that particular sensor, & then makes adjustments & compensations for it, while at the same time doing the same with from 6-13 other sensors. heavy voltage dips can & do upset these delicate balances at times & I have seen more than a few vehicles with buggy problems that can be traced back to voltage variations, although the majority of times it is never actually realized as related.
the cap can act as sort of a shock absorber, by providing the big instant hit of extra amperage at the right time, thereby taxing the electrical system that much less. depending on how much is needed this may or may not make all the difference needed. an aux battery in the rear will kind of act as a spring, by being able to help deliver power under those same conditions, but for a longer period of time than a cap. the real difference is how "fast" the power demand is needed. Think of a cap as a sledge hammer, quick short bursts of power, but with a pause inbetween for recharging(backswing). now think of the battery as a helper pushing. you will get the best results by having one guy pushing while the other swings away with the sledge hammer, all being perfectly timed by the physics of the demand at hand.
I have built pro systems that will run at say 1,200 true rms, & powered it more than adiquate with a 4 gauge run from the front to the rear battery, which is close to the amps. from the rear battery you would give each amp the power it needs, with even a 0 gauge for the sub amp & cap bank, 0 gauge ground to frame. now keep in mind that the 4 gauges only job is to charge the rear battery, which in turn really supplys the system. the 4 gauge will not be overloaded because on average it is only providing the 30-50 amps required to maintain battery voltage in the rear, & the majority of the quick instant heavy short loads are handled by the rear battery & caps, never actually overtaxing the front of the vehicle itself. This is varified by the fact that I can run this system with an 80 amp breaker inline front 4 gauge without ever blowing it. actually the only way to blow this 80 amp breaker is if the front battery went dead & then I tried to crank off the rear battery, or boost the vehicle from the rear. this system had a peak draw of almost 200 amps & it never saw the front of the vehicle.
anyone who tells you that a battery is better, or a cap is better, is not taking the whole picture into account. if I had to choose between one or the other in an install, I would pick the battery, but honestly they work best togeather. a batcap is kind of a melt between the two, but doesn't acheave the peak benefits of either, sometimes it can be a reasonable compromise when space is restricted...
yeah what he said
good post, but it doesnt take into account two things.
#1, most people dont care about power dips. like you said, the car is built to take it, by running the car computer at 5 volts. you say this allows for regulation to prevent effects from varying voltage. Why cant we regulate the power supply that goes to the computer? the answer is we can, and if we experience computer problems because we CHOOSE not to regulate the power, thats our fault, not the E-system's fault.
#2 rule of thumb for disease: cure the symptoms, cure the disease. you have food piosoning, or cholera, or giardia? what do you do, cure that, or do you merely drink a crapload of water to prevent our body form dehydrating and shutting down (dying) as a result of it?
the fact is, most people never see the effects of varying voltage. Furthermore, I think it wouldnt be so far fetched of a claim to say that every car experiences voltagae dips, and to say that because a few people put in multi-killowatt systems without taking precautions or educating themselves on safe stereo use and as a result had to replace the alternator, saying that these few (percentage wise) that the alternator upgrade is paramount is absurd.
Thus, to suggest an alternator upgrade is *neccesary* for the standard enthusiast may be a bit extreeme, voltage dip or no! your argument itself suggests two cheaper ways to sufficiently lower voltage dips to prevent equipment breakage: increase capacitance to sufficiently reduce voltage drops, and regulate the power supply that powers suceptible electronics.
Check out the link I provided earlier. Christopher gives many reasons why each upgrade is desireable, what it will help, what it wont, and suggests a logical order of upgrade, and why. its a bit similar to most of what youve wrote, but goes more in depth, with a visual or two to demonstrate his (and your) points.
its a good read, and will help you flesh out your argument so that it better applies to the standard enthusiast, as opposed to the few elite your argument is taylored to.
...I never said to replace the alternator, quite the opposite really. the only time you will NEED to replace your alternator is AFTER you have already done steps 1 & 2, & then realize that your average draw is above your average output. You would realize this after pounding the system for a long time & then shut the car off, just to realize that the battery voltage is too low to restart the car. you could also avoid replacing the alternator by just not pounding it too much for too long, & let the vehicle idle for a while to recharge before shutdown, I think too many run out & replace the alternator before exploring these other options, which should always be done first, even if you are going to replace your alternator I still say you should install a rear battery & cap.Originally Posted by WhiteRabbit
You are right in saying that most will not see these issues arise as a problem, but keep in mind that most people on a board like this are less likely to "settle for.." or accept not having what they desire, otherwise they would just settle for the vehicle as-is & not modify anything.most here are on a mission to build what they desire or envision & are conditioned to try & compensate for any percieved deficencys in there vehicle, to just say you don't need this is not acceptable, afterall, how many of us actually NEED a pc in our dash...
as far as going into more depth, I think I went quite as deep here as I can justify on just a bulletin board post, I could go on for pages & pages, but I am trying to condense it down to something easy enough for the casual reader to understand & absorb & benefit from, without going into really technical explanations that are not really called for here. I wish I could show you before & after ossiliscope readings to show you what I am talking about, but really I only care so much here If someone desires to kow all there is to know then they can search & research to there hearts content, your link is a great place to start...
to me the bottom line is that the people here that are questioning this issue & looking for a solution are doing so for two main reasons, either to solve a problem that has been created or to prevent a problem from occuring. this is afterall a vehicle we are talking about & everything we are adding is fine & dandy, but we must preserve the basic functionality & reliability of the vehicle too. I don't think it' fare to say that only a competition guy deserves a reliable electrical system, to me it is probably more important that my daily driver is reliable & up to the job at hand, than my competition car, that I can charge between competitions & trailer home...
...oh, & 1 more thing, even though the on board computers will use a regulated 5v reference, it can & is still affected buy these large surges enough that the 5v can fluctuate enough to affect the delicate balance, the regulators built into an ecm is not designed to give a rock solid 5v no matter what, & when the battery voltage drops by 2 volts or more instantaniusly & repeatedly, the on board voltage regulator can not keep up & will fluctuate a little. some may never be aware of, or ever see any negative results of this, but others can & do have problems, whether just an unexplained surge once in a while or premature falure of components involved.
a 97 sentra may feel no ill affects mechanically, other than maybe toasting an alternator if severe enough, but try this on a late model beemer or benz & you will increase your chance of it afecting delicate electrical systems... try going to the dealer with a trunk full of amps & see how fast they deny the warentee claim on a damaged suspension computer, you may be ****ed but they may be correct when they tell you that the system probably caused your problem...
you don't really need a solution unless you have a problem, & in my eyes if your car is dimming regularly then you have a problem, what it will affect & how long it will take can vary widely, but wouldn't you rather eliminate the potential of a failure which you never know if or when is coming...
Ok... For everybody argueing on this thread. Im going to set the entire record straight.
As a Licensed Ham Operator, im going to set you all straight.
A Capacitor is used in an electrical circit to 1. Smooth out Distortion in Current Flow/IE Amperage or I in Ohm's Law of electrons, for all of those that I have lost at this point Google Ohm's Law and Learn some things, as the one user stated he seems to somewhat be understanding what a capacitor does/is. The biggest Number 2. thing a capacitor does is it works as a part of an electrical circuit to retain a charge even after a battery looses Amperage or current. Which is why a "CAP" as you all are calling it, can stay on even if the Voltage to the circuit is considered to be OFF. Don't beleive me? Try it charge your, "CAP" then remove the charge then check with a Volt meter if needed, and be amazed as you see a high voltage still come across your meter even 30 min later. The reason is a Capacitor is designed so that when placed in an electrical circuit it, "RETAINS" an electrical "CHARGE" or voltage, then when a certain amount of, "VOLTAGE" is reached depending on the Size of said capacitor, that voltage is then "REALEASED" as Amperage, and current flow. So. Let's recap.
A capacitor Builds Electroical Current which is then Later Released. Meaning, "YES" technically it is drawing more Amperage and current from the Battery/alternator. Although, the purpouse of the device must be remembered, Technically this electonical componant takes some of the burden off of the Battery, which does take Some of that "JOLT" from a punch type bass that a set of subs/amplifier or car audio LINEAR/KICKER is going to require.
Meaning yes the, "CAP" as your calling it, does require some power. 12v. Although, this device is then keeping your amplifier in theory at a CONSTANT of 12v or higher. Meaning there is Equal Bass and your System will then not have as much of a fadding issue after the first few good sounding hits. This is why it also helps keep you from looking stupid with your headlights diming and makes your ride look more, "PROFESSIONAL" because then when you subs hit and amp, your not LOOSING amperage that was needed elsewhere, as it is stored when your subs aren't hitting in the capacitor as excess. In most forms of regular music you notice your subs don't always hit right? What the Capacitor does is stores what could have potentially been lost PEAK voltage into the Capacitor for possilbe later use. Meaning Less harm to your electrical system of your car/battery/and your alternator. In the end it will improve bass i've not only witnessed it, its just the way the device functions it simply HAS to if it doesn't you did something wrong.
Now, a second battery wired in SERIES, will also increase Amperage/voltage abilities yes. Although this is better served in CONJUNCTION with a Cap Now that you know the difference of the two devices. A Cap will discharge slowly and will Never Hold a Charge like a battery. Although, Don't misunderstand the difference. Cap is temporary help, The Battery is the SOURCE of your, "MAIN" power cell in which your Cap depends on and your amp and your system as a hole. So both are important depending on how Much power you really truely require. I have yet to build a system that doesn't require a cap.
Finally, a high output alternator/or beefing it up, is also advised. As the other user said and he is completely correct. You need to remember that cap only improves your amperage based on what there is to OFFER, ok? Meaning if your car puts out 90amps off of your alternator and 60amps are used by your car for normal operation, that leaves a mere 30 ampers for your system as excess Power going to your battery and then to your cap then to your d-block or maybe just straight to your amp if you don't require a d-block and don't have 2 amps in your ride. SO you can now see the line of devices. If one is weak it effects the other because of this. If one is weak the other picks up the slack in the electrical circuit which is bad, which means less peak envolope power than you could potentially have, which is weakening your system, and also could cause bigger problems such as shorts, bad alternators on a trip to your girls place, "WHICH could be very embarrasing." Dead batteries, which then have to be replaced you get my drift. They all work together in that circuit.
And to the gentlemen that said Capacitors are useless, then why does the computer your using to communicate use them? They obviously do serve a purpose in an electrical circuit, and if they didn't we would use them in our hams, radios, cb's, tv's, computers and any other peice of electonics you've touched in your life to increase power abilities. For example, "Law enforcement" wouldn't have Tazer's or stun gun's in their hands if it wasn't for the capacitor creating huge increases in avalaible voltage, There is no way a straight 9v battery, nor a pair could make 400,000 volts, although combine a ton of capacitors in series after those batteries, and wella you have one hell of a jolt of electricty you can offer in seconds. So before you go making hasty claim's of a electrical componant being useless i suggest you study electric fundementals a tad deeper.
Licensed Ham operator/ Admin at www.radarreviews.net