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Car Forum / Driving, Maintenance, Tuning / Car Audio / July 2006Dimming of lights even with modest setup and cap...Help
What is the typical load on a vehicles stock electrical system (2000 Accord LX) that will cause headlight dimming? The reason I ask is that I have installed a rather modest system including a 1farad capacitor and my light are dimming. My Interior amp is Alpine MRV-F505 rated @ 50x4 (4 Ohm) @ 12.2v. The sub amp is an Alpine MRV-1000 rated @ 100x2 (4 Ohms) rms. @ 12.2v. Connected to the sub amp is a 20-volt 1-farad monstercap stiffening capacitor. At the present time I only have a single Orion DVC ten in a sealed box with the voice coils wired independently @ 4 Ohms (no great shakes Iassure you, upgrading shortly). I have the capacitor as close to the amp as physically possible (aprox 6 inches of 8 gauge from cap + terminal to amp + terminal). But the lights are dimming! Why? Does this little 100x2 rms. @ 12.2 amp really require enough juice to drop the current enough to dim the lights? Having said al this, I am experiencing headlight and interior light dimming. I had purchased the cap with this in mind in order to prevent this. Before I go and buy a $500.00 alt or $250.00 battery (as suggested on other posts) My understanding was that 1.0 farad would be required per 1000 watts. However my current sub setup is well below that. Why do I have the cap at all if I can just remove it from the setup and get the same performance? Any thoughts or help are greatly appreciated...Just to let you know I am asking for help, not opinions...I am new to this and I just need a practical solution... Your Accord alternator should be good for around 80amps and that should be enough to power those alpines. The 1 farad capacitor wont do much for your headlights and to be honest I think that the rule of thumb that a 1farad capacitor is good for a 1000 watts is totally over rated. I would start by having the battery tested before buying anything. Is that still the factory battery that you have in the car? If you do end up looking for another battery what you want to look for is a battery that has the most cranking amps that will fit your car. Something like 850-1100 CCA would be nice if you can find a good fit. >What is the typical load on a vehicles stock electrical system (2000 >Accord LX) that will cause headlight dimming? The reason I ask is that [quoted text clipped - 23 lines] >am asking for help, not opinions...I am new to this and I just need a >practical solution... OK, before we get to the expensive fixes let's explore the inexpensive fixes. First, you need to check and see if your neg. potentials all match up. If the neg. potential of your battery is significantly different than the neg. potential of your chassis or engine block, your amp will not get the maximum voltage. Remember, voltage is not an absolute value, it is the difference between the positive AND negative potential. Often, people focus too much on the positive potential. You need a mulimeter (or a voltmeter). Then crank your system and measure the voltage differential between the neg. terminal on your battery and your engine block AND your car's chassis (put one probe on the neg. battery terminal and the other probe on the chassis and then block). It's is important to be cranking your system when you measure these things as the voltage differences will increase with large current draws. If you get readings greater than .1 volts (which I'll bet you will), you can increase the voltage at your amp by just adding a 4 gauge (2 gauge is better) connection between your neg. terminal and chassis, and then I would add a couple large connections between the chassis and engine block (and it wouldn't hurt to put one between your neg. battery terminal and engine block). Then re-measure, it should be better AND you will notice more voltage at the amp AND it may COMPLETELY solve your dimming problems, especially if your differential drops are approaching .5 volts. That's the low cost fix. The NEXT thing I would do is add an Optima Yellow Top battery. The Optima has the lowest internal resistance of any battery which means when the engine is running there is more current available to your system. I noticed a DEFINITE difference when I installed mine. My dash/headlights lights dimmed a little before, but the Optima REALLY DID make a big difference. And, one more farad of capacitance wouldn't hurt either. I have ALWAYS thought that one farad for every 1000 watts is COMPLETELY BS (it was cooked up by David Navone and Richard Clark for their own company, Autosound 2000, and I think it was just a arbitrary guideline that was needed for marketing reasons). For a system of your size, it would take AT LEAST two farads before you notice a difference. Also, keep in mind, all these things I have mentioned ADD UP to give you additional voltage. If you have a weak link in your power chain, it may cancel out other things you have done (like the caps). Take a look at the neg. potential first. This is what you NEED to make sure is good before you proceed with caps, battery, etc. Good luck, MOSFET I'm not saying a damn thing. LOL >OK, before we get to the expensive fixes let's explore the inexpensive >fixes. First, you need to check and see if your neg. potentials all match [quoted text clipped - 42 lines] > >MOSFET > I'm not saying a damn thing. LOL > [quoted text clipped - 40 lines] >>neg. potential first. This is what you NEED to make sure is good before you >>proceed with caps, battery, etc. Er.. how does more capacitance give you "more voltage"? And how much more voltage do you want anyway? Any more than 15 volts and things are gonna start frying in that car... >> I'm not saying a damn thing. LOL >> [quoted text clipped - 45 lines] > voltage do you want anyway? Any more than 15 volts and things are gonna > start frying in that car... Oh, I hate the nitpickers..... OK, I meant a smaller voltage drop when there's significant current draw, OK!!! And, BTW, Matt, I disagree with your assessment that he should go right to a HO alternator. These things I have suggested have made a HUGE difference in small cars I have owned (otherwise, I would not have suggested them). His system is not THAT huge, and by beefing up his existing electrical system, he SHOULD be able to handle that much current. FURTHMORE, these things I have recommended SHOULD be done even if he eventually needs to put in a HO alternator. I mean, Matt, if the return flow of electrons can't make it back to the alternator, what the heck's the point of a HO alternator? AND, these things are much, much less expensive. If you bothered to read the original post, the guy said he DIDN'T WANT TO SPEND A LOT OF MONEY. If he had said "sky's the limit", I would have FIRST recommended a HO alternator. MOSFET > ...That's the low cost fix. The NEXT thing I would do is add an Optima Yellow > Top battery. The Optima has the lowest internal resistance of any battery > which means when the engine is running there is more current available to > your system. I noticed a DEFINITE difference when I installed mine. My > dash/headlights lights dimmed a little before, but the Optima REALLY DID > make a big difference... > Good luck, > > MOSFET Well I will be checking the grounds for voltage variance for sure, thanks. Now when you say " add an Optima Yellow Top battery", do you mean in addition to the current battey or to replace the current OEM battery with an Optima Yellow Top battery? Thanks so much for the advise... No, you don't want to add a battery as that will just be another load on your electrical system. What I meant was replace your factory battery. And as I said before, the ground thing I talked about is REALLY important. It may be part of the reason your capacitor is not providing as much help as you would like. Ideally, you want there to be zero voltage differential between your neg. battery post, the car's chassis, and the housing of the alternator (however, the engine block is generally exactly the same as the alternator housing). You would think that the engine block and car's chassis would have very little electrical resistance between the two things, but I have found in newer cars manufacturers try to isolate the engine block from the chassis for a smoother ride (with rubber mountings and what not). This is PARTICULARLY true with smaller cars as they have four and six cylinder engines which are not as smooth running as eight cylinder engines. So even though your car's body makes, in effect, an OUTSTANDING large gauge return wire back to the alternator, it doesn't quite make it back all the way. Several short 4 gauge connections between the car's chassis (it doesn't matter where) to the engine block can make a VERY surprising difference. MOSFET >> ...That's the low cost fix. The NEXT thing I would do is add an Optima >> Yellow [quoted text clipped - 14 lines] > battery with an Optima Yellow Top battery? Thanks so much for the > advise... Well, I did some looking around for Optima batteries and it seems that here is not a recommended model for my car (2000 Accord LX) according to the Optima website in addition to Advance Auto on-line, or AutoZone. So.... Would you recommend that I simply find any battery with comparable cranking amps to the Optima models? Or does it really make a difference; can I just get Optima battery that fits and stuff it in there? I appreciate the advice regarding the grounds, I am going to try and find some time to take a look. As I am planning on upgrading as I go. The battery thing I should probably do anyway as I move along...Another quick question though, remember I am a newbie to this and I am not "up" on my mathematics and/or electromagnetic theory, but my next move is to upgrade my sub. I am not sure exactly what set up I will go with (single or dual) but my amp will be running @ either 400 watts rms. @ 4 Ohms (Mono mode) or 200x2 @ 2 Ohms. Right now I am just running at 100x2 @ 4 Ohm. I don't know if it makes any difference but if/when I make the sub change before I address the ground/battery issues, would this in any way exacerbate the problem further, dimming even more drastically? Thanks again... > Well, I did some looking around for Optima batteries and it seems that > here is not a recommended model for my car (2000 Accord LX) according [quoted text clipped - 18 lines] > way exacerbate the problem further, dimming even more drastically? > Thanks again... Look... your lights are dimming because your alternator isn't providing sufficient current. By the time you go putting in a fancy battery, more super-duper power wires (although beefing up the battery-to-chassis ground is a good idea) and another farad or three of capacitance, you could have just got a stronger alternator and been done with it. If your current alt really is being overloaded that badly, you'll end up frying it and having to replace it soon enough anyway... so save the hassle and expense and just get a high-current unit right off the top. A failing battery can and will place an extra load on the alternator. Also, the alternator does not respond to amperage spikes fast enough to deal with headlight flashing alone and at idle the alternator won't do a damn thing for your headlights. I bet that some of you have seen high output alternators that are rated at 70-90 amps at idle, what they don't tell you is that this rating is in an unregulated state and it doesn't mean jack while mounted in a car with a voltage regulator in place. >Look... your lights are dimming because your alternator isn't providing >sufficient current. By the time you go putting in a fancy battery, more [quoted text clipped - 8 lines] > unit >right off the top. |
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