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Car Forum / Driving, Maintenance, Tuning / Car Audio / January 2007Capacitor Drains my Battery
There was another thread about this but my problem is slightl different. What I have is: 90Amp Stock Alternator Evermaxx Gold Battery (Walmart) Power Acoustik 2 Farad Cap Stinger 4 Gauge Power wire When i installed it ,when i got it, It had never drain my battery. Bu when i had replaced my Battery terminals it had all started. When reconnected my Capacitor to the battery(it was Discharged) it seeme perfectly fine. Cap was fully charged to 12.3v W/car off. Within week if reinstallment i turned over the ignition this one morning an my battery was dead. Looked back at my cap and it was blinking 10v. I disconnected the Capacitor's Negitive and kept it like that for months and never had the problem of drainned battery. Can anyone tell me why it does that and How do i PROPERLY install a capacitor?(connect positive first then th Ground last or vise versa -- jimbo_limited > There was another thread about this but my problem is slightly > different. [quoted text clipped - 5 lines] > Power Acoustik 2 Farad Cap > Stinger 4 Gauge Power wire You don't mention what kind of car it is, or what amps you have, but I would guess that your first problem is, your alternator is underpowered. Any system that's drawing enough current to need a 2F cap is probably going to need a LOT more than a 90A alternator can provide (depending on how much the car iteself requires). If a 90A alt is generating enough to run your system, then you DON'T need a cap, let alone a 2F. > When i installed it ,when i got it, It had never drain my battery. But > when i had replaced my Battery terminals it had all started. When i [quoted text clipped - 5 lines] > I disconnected the Capacitor's Negitive and kept it like that for 2 > months and never had the problem of drainned battery. Sounds like the cap may be leaking internally. This is easy to test: connect it, charge it, then disconnect it, and watch the voltage over time. If there's no load on the cap, its voltage shouldn't drop noticeably (it will fall over time, but we're talking probably weeks if not months for it to be measurable on the built-in display). > How do i PROPERLY install a capacitor?(connect positive first then the > Ground last or vise versa) The order you connect it doesn't matter. What DOES matter is that you connect some resistance in series with it when charging it. Unless it has built-in resistance for charging, an uncharged cap will initially appear to the car as a dead short, and could damage your alt, battery, and/or wiring. The most common method is to connect the cap's ground, then connect any standard automotive light bulb (like a turn signal bulb) inline with the power wire - the bulb will go on brightly at first, then dim slowly as the cap charges. When the light goes out, the cap is charged - you can then remove the bulb and connect the power directly. That's not going to work. as soon as the cap is disconnected it will drain in a minute or two. My take on this problem is that the battery is crap and dropping voltage when the car sits and is triggering the cap's auto discharge. Have the battery tested and see what it has for cranking amps vs what it's rated for. Digital caps are a little nasty when it comes to weak batteries or batteries that don't get a full charge. If the car sits for a few weeks it's best to disconnect your main power line fuse or replace the fuse with a circuit breaker for an easy disconnect or replace the cap with a non digital type or a remote triggered digital type. >Sounds like the cap may be leaking internally. This is easy to test: connect >it, charge it, then disconnect it, and watch the voltage over time. If there's [quoted text clipped - 3 lines] > >the built-in display). > That's not going to work. as soon as the cap is disconnected it will drain in > a minute or two. To where??? A *good* capacitor should hold a charge almost indefinitely, unless it's got built-in circuitry INTENDED to drain it. > > That's not going to work. as soon as the cap is disconnected it will drain in > > a minute or two. > > To where??? Yes, to where? I have a 1/2 farad cap sitting right next to me that I took out of a car 15 months ago. It is still reading 10.5 volts. MOSFET >>>That's not going to work. as soon as the cap is disconnected it will > [quoted text clipped - 8 lines] > I have a 1/2 farad cap sitting right next to me that I took out of a car 15 > months ago. It is still reading 10.5 volts. Holy crap, MOSFET lives! > Holy crap, MOSFET lives! Yes, I'm still here. Though I felt I needed an extended break. You better than anybody should know the reason. When a pastime no longer becomes fun, it's time to look for other pastimes. I found myself a little TOO involved with RAC and thought a break would be nice. ;) Glad to see you are still offering up EXCELLENT advice. See ya, Nick >>Holy crap, MOSFET lives! > [quoted text clipped - 4 lines] > I found myself a little TOO involved with RAC and thought a break would be > nice. ;) I dunno, I only left when it got boring. > Glad to see you are still offering up EXCELLENT advice. All for you, baby :) If there is a loose or weak connection on a cap, the cap will discharge itself. This will create a greater defference in charge from the battery and the cap positive terminal, which in turn creates a spark and the cap charges, then loses connection, discharges..... wash, rinse, repeat, wash, rinse, repeat........ This will drain the battery in a number of hours. Also, depending on the sensitivity of the cap LED readout electronics, if your radar detector goes off, that could be enough of a voltage drop to make the LED readout light up. This is highly unlikely to drain the battery in a day or two, but a week of just sitting there, it could happen. Caps are just eye candy anyway, sell it and buy a yellow top. The difference is amazing. > If there is a loose or weak connection on a cap, the cap will discharge > itself. And how does it do that? > Caps are just eye candy anyway, sell it and buy a yellow top. The > difference is amazing. You want a DIFFERENCE, upgrade your alternator to provide sufficient current to begin with. Within the last 4 or 5 years companies started making capacitors designed to discharge themselves when removed from the vehicle for safety reasons. (probably because people were sticking their toungues to the posts). An older cap with no LEDs or digital readout can hold a charge for a long time. The newer ones do not. It is not that they can not, just that they are designed to bleed off when power is removed. Yes, a HO alternater is the best bet, but when you are talking about the average car audio enthusiast, they are not going to spend $500-$600 on a 200amp alternator. A $200 battery is a more economical choice. I have one yellow top and a stinger 200a HO alternator in my car, and no caps. I don't believe in caps. They work only when you listen to rock where the bass consists of bass drum thumps, and the current draw of the amplifier is spiked occasionally (with the bass drum thump). The pause between allows the cap to charge back up and it effectively does its job as a buffer and stabalizes the current draw so that it dosen't dim the headlights. Listening to low sustained notes (rap or bass CDs) does not give the cap a chance to recharge, therefore it does not do any good. > Yes, a HO alternater is the best bet, but when you are talking about > the average car audio enthusiast, they are not going to spend $500-$600 > on a 200amp alternator. A $200 battery is a more economical choice. Yes, but it is typically the WRONG choice. There is only one thing in your car's electrical system that CREATES electricity, and that's the alternator. If it's not producing enough, the battery is not going to fix that problem. A bigger battery will allow him to run the stereo longer with the engine off, but it's not going to magically create more power out of thin air. If the lights are dimming and the voltage is dropping because the alt isn't producing enough current, all the battery is going to do is stop that drop at 12-13V, rather than letting it fall further. Adding a battery or a cap to "solve" your low-current voltage-dropout issues is a band-aid at best: it's attempting to cover up the problem without actually FIXING the problem, which is a lack of sufficient current. This guy didn't even say what size amp he has. Stock alternators are rated at 10% over maximum vehicle current draw, so that leaves us with 9-14 amps to spare. 14 amps x 14.4 volts = 201.6 watts. So what you are saying is that everyone with a 200 watt amplifier or more should buy an alternator? Are they WRONG if they don't? I didn't say that a battery would magically create electricity, I said a yellow top was better than a wet cell battery and a 2 farad cap. I'm not here to steal your glory Mr. Ion, I just thought I would drop by and respond to a few questions. Bottom line, I agree with you..an alternator is the ultimate fix. Informing people of that is important, but alternators are not the only option. You can have a nice setup without having a HO alt. You just have to understand that you are limited in the amount of current draw and the length of time you are using that much current. > This guy didn't even say what size amp he has. Stock alternators are > rated at 10% over maximum vehicle current draw, so that leaves us with > 9-14 amps to spare. 14 amps x 14.4 volts = 201.6 watts. So what you > are saying is that everyone with a 200 watt amplifier or more should > buy an alternator? Are they WRONG if they don't? No, I'm saying that IF YOU HAVE A CURRENT-SUPPLY DEFICIENCY in your system, the ONLY *FIX* for it is a more powerful alternator. A battery will not fix the deficiency. > I didn't say that a battery would magically create electricity, I said > a yellow top was better than a wet cell battery and a 2 farad cap. Better for what? A better battery will run your system longer without the engine running. Nothing more. If the cap is draining the battery, a shiny new $200 Yellow Top will give him more time before the battery goes dead, but it's not going to fix his problem. Caps are *typically* added for two reasons: someone told a n00b that it would fix the problem with his lights dimmer, or someone told a n00b that it make his system sound better/hit harder/whatever. Chances are good that the OP here *does not need* a cap at all, and if he does have the symptoms that lead him to think he needs one, it's probably an attempt to overcome a current deficiency, which requires a better alternator, NOT a better battery. > not here to steal your glory Mr. Ion, I just thought I would drop by > and respond to a few questions. Are you related to MOSFET? I don't give a sh.t about "my glory", only about providing good advice. Telling the OP that a big fancy expensive battery is the cure for his ills is not good advice. That is all. > Bottom line, I agree with you..an alternator is the ultimate fix. > Informing people of that is important, but alternators are not the only > option. You can have a nice setup without having a HO alt. You just > have to understand that you are limited in the amount of current draw > and the length of time you are using that much current. Upgrading your alternator and upgrading your battery are not "options" related to each other. Each addresses a different need. If he needs a better alt, a fancier battery is not an "option". If he does in fact need a better battery, then putting in a jacked-up alt isn't an "option". The OP may have a failing battery and need to replace it, but there's nothing in his post that suggests he really needs a $200+ super-duper battery. The yellow top will take alot of load off the alternator, so the yellow top will help to a point. >> This guy didn't even say what size amp he has. Stock alternators are >> rated at 10% over maximum vehicle current draw, so that leaves us with [quoted text clipped - 46 lines] > he >really needs a $200+ super-duper battery. > The yellow top will take alot of load off the alternator, so the yellow top > will help to a point. How does a battery "take the load off" the alternator? ANY energy drained from the battery eventually needs to be replenished, and that comes from the alternator. > How does a battery "take the load off" the alternator? ANY energy drained from > the battery eventually needs to be replenished, and that comes from the alternator. True. What a yellow top battery does is spread out the alternator cycles. The alternator does not run all of the time, if it did, I could see your point. The vehicle runs off the battery until the battery starts to show a voltage drop, then the voltage regulator tells the alternator to come on. And even then, the alternator is not wide open. The regulator works like a transistor, telling the alternator how much voltage is needed when running. If a higher capacity battery is used, the alternator does not have to work as much unless it is under a severe load. Given time to recharge the battery (removing the load from time to time) the alternator can go longer periods in idle mode. Also, a deeper cycle battery can absorb larger spikes in demand and buffer them from the regulator so the alternator does not see an 'instant on' signal. This reduces the number of unnecessary cycles as well. My personal favorite trait of a dry cell battery is that if it goes dead, it will recharge. Wet cell batteries won't live after 3 or 4 complete dishcarges. Dry cells will actually recharge themselves enough to crank the vehicle after a complete discharge, plus you can do this 100 or so times before any damage is done to the battery. This is how I explain the vehicle charging system to my customers: The alternator is like your job.. The output of the alternator is how much money you make. The battery or batteries are your bank account, and the amplifiers are your wife/girlfriend's spending habits. If you have a bigger bank account, you don't have to worry too much about how much money is in the bank all the time. If you live paycheck to paycheck, you have to work overtime trying to keep up with their shopping sprees. If you have money in the bank and only make minimum wage, you can still save up and let her buy something nice every once in awhile. This is a loose comparison, but it works to explain how everything goes hand in hand. >>How does a battery "take the load off" the alternator? ANY energy drained from >>the battery eventually needs to be replenished, and that comes from the alternator. [quoted text clipped - 5 lines] > to show a voltage drop, then the voltage regulator tells the alternator > to come on. A vehicle never runs off the battery. The alternator is DESIGNED to provide power for all the vehicle's systems, including ignition. The only thing the battery is NEEDED for is cranking the starter. Yes, it does perform other functions, but none of them are NECESSARY. > The alternator is like your job.. The output of the alternator is how > much money you make. [quoted text clipped - 7 lines] > in awhile. This is a loose comparison, but it works to explain how > everything goes hand in hand. In the end, all the money still comes from the same place, it still costs you the same amount of money, and you still have to do the same amount of work. And in keeping with your analogy, in the end, regardless of what type of battery you have, IT STILL REQUIRES THE SAME TOTAL ENERGY, and ALL of that has to come from the alternator. The optima's charge alot faster then lead/acid batteries they also don't drop voltage as fast as lead/acid batteries. Freeing your alternator to do other things then charging your battery. >> The yellow top will take alot of load off the alternator, so the yellow top >> will help to a point. [quoted text clipped - 3 lines] >the battery eventually needs to be replenished, and that comes from the > alternator. > The optima's charge alot faster then lead/acid batteries they also don't drop > voltage as fast as lead/acid batteries. Freeing your alternator to do other > things then charging your battery. A battery that charges faster requires more current. Either way, it requires the same amount of energy. I still don't see how that "takes the load off" the alternator. Either it's more current for a short amount of time, or less current for a longer amount of time; either way, it's the same ENERGY requirement, and the same total LOAD. >>>The yellow top will take alot of load off the alternator, so the yellow top >>>will help to a point. [quoted text clipped - 3 lines] >>the battery eventually needs to be replenished, and that comes from the >>alternator. Yes if you are comparing lead acid batteries., but these two types of batteries are far from an equal comparison. The technology is totally different between the two. I personally don't know enough about the inner workings of "SPIRALCELL" batteries to tell you why they charge faster at the same current then acid batteries, but they do. In article <0rwmh.553254$R63.334777@pd7urf1no>, Matt Ion <soundy106@gmail.com> >A battery that charges faster requires more current. Either way, it requires >the same amount of energy. I still don't see how that "takes the load off" the > >alternator. Either it's more current for a short amount of time, or less >current for a longer amount of time; either way, it's the same ENERGY >requirement, and the same total LOAD. > Yes if you are comparing lead acid batteries., but these two types of > batteries are far from an equal comparison. The technology is totally > different between the two. I personally don't know enough about the inner > workings of "SPIRALCELL" batteries to tell you why they charge faster at the > same current then acid batteries, but they do. Thermodynamics states that energy can be neither created nor destroyed. I don't care how "special" the inner workings are, the more energy you want to store in the battery, the more you have to provide it. Power is a pretty simple equation, P=IV, power = current times voltage. The more power you want to store in the battery, the more voltage or the more current you have to give it. Voltage is more-or-less a constant here, so the variable is current. You want more power, you need more current. Charging in less time requires more current. Basic 11th-grade physics. > In article <0rwmh.553254$R63.334777@pd7urf1no>, Matt Ion <soundy106@gmail.com> > [quoted text clipped - 4 lines] >>current for a longer amount of time; either way, it's the same ENERGY >>requirement, and the same total LOAD. If you take C=RS=L^/799999999.98 you will see that resistance and leakage plays a major factor in how fast a given battery will charge with equal current.It really simple optmatics. With that said, a discharged capacitor should charge much longer then a discharged battery given that it will output more current at the same voltage as a battery. >Thermodynamics states that energy can be neither created nor destroyed. I > don't [quoted text clipped - 20 lines] >>>current for a longer amount of time; either way, it's the same ENERGY >>>requirement, and the same total LOAD. > > This guy didn't even say what size amp he has. Stock alternators are > > rated at 10% over maximum vehicle current draw, so that leaves us with [quoted text clipped - 5 lines] > ONLY *FIX* for it is a more powerful alternator. A battery will not fix the > deficiency. That is what I said. If you define a current-supply deficiency as using more than the alternator will produce, a 200watt amplifier will produce a current supply deficiency, and in your words, the ONLY *FIX* is a more powerful alternator. But you are wrong. A better battery will supply the stereo system with the current required for significant amounts of time, especially when the engine is running. You just have to turn it off occasionally to let the alternator charge it back up. Most batteries have a CCA rating of around 400 amps, so if the alternator is running at its prime of 90, and the car is using 50, you have 40 amps for the system and the battery can easily make up another 60-80 amps if needed, up to 400 on a spike. You just can't run it all the time. It is not as cut and dry as you think. It's not as simple as alternator OR battery. It is knowing how to use what you have / what you can afford. > > I didn't say that a battery would magically create electricity, I said > > a yellow top was better than a wet cell battery and a 2 farad cap. [quoted text clipped - 3 lines] > $200 Yellow Top will give him more time before the battery goes dead, but it's > not going to fix his problem. your answer to this question is in the quote right above it. A Yellow top IS BETTER THAN a wet cell and a 2 farad cap.... If you only have a yellow top, and not a cap, how can the cap drain the yellow top? > Are you related to MOSFET? I don't give a sh.t about "my glory", only about > providing good advice. Telling the OP that a big fancy expensive battery is the > cure for his ills is not good advice. That is all. Telling someone a big fancy $600 alternator is the cure, is that good advice? Especially when the $200 battery will help? > Upgrading your alternator and upgrading your battery are not "options" related > to each other. Each addresses a different need. If he needs a better alt, a > fancier battery is not an "option". If he does in fact need a better battery, > then putting in a jacked-up alt isn't an "option". The OP may have a failing > battery and need to replace it, but there's nothing in his post that suggests he > really needs a $200+ super-duper battery. In the case where the battery is bad, which is all I wanted to suggest in the first place, replacing it with a battery that has a faster discharge rate, a higher capacity, a deeper charge cycle, and can be run completely down 100 times more than a wet cell, IS IN FACT a better option. >This guy didn't even say what size amp he has. Stock alternators are >rated at 10% over maximum vehicle current draw, so that leaves us with [quoted text clipped - 6 lines] >and respond to a few questions. >Bottom line, I agree with you..an alternator is the ultimate fix. If your idling, a cap has a tremendous advantage. A bigger alternator is not going to make much difference, unless its on a variable diameter shaft to control its RPM and maintain a high charge capability. Unless the alternator and battery are next to the amp, the cap will win at providing peak power capibility. greg >Informing people of that is important, but alternators are not the only >option. You can have a nice setup without having a HO alt. You just >have to understand that you are limited in the amount of current draw >and the length of time you are using that much current. > If your idling, a cap has a tremendous advantage. A bigger alternator > is not going to make much difference, unless its > on a variable diameter shaft to control its RPM and maintain a high > charge capability. Unless the alternator and battery are next > to the amp, the cap will win at providing peak power capibility. In this situation the cap will win for one bass note, then it is discharged, and now creates more stress by trying to recharge itself. A higher output alternator would work here because the output of a HO alt is higher than a standard alt. at idle RPM. Capacitors were first used in competition car audio for that one note. It became a fad, and now everyone uses them. "The power cap, usually 1 or 2 farads, is connected in parallel between the battery and the amplifier. Multiple capacitors can be connected with busbars to reduce resistance and power loss. The capacitors are quite large and are often decorated with graphics or enclosed in an attractive housing, sometimes with readouts to monitor the capacitor's voltage. It can only hold a small charge, so a single bass hit can empty it completely. It charges back up when there isn't a large power demand. This makes it inappropriate for systems that will require prolonged delivery of power, as the capacitor cannot supply additional power, only store it temporarily." - http://en.wikipedia.org/wiki/Stiffening_capacitor Facts about a standard car battery: "A lead-acid battery has an efficiency of only 75-85%. The energy lost appears as heat and warms the battery. Keeping the charge and discharge rate of a battery low, helps keep a battery cool and improves the battery life. The above losses don't include losses in the charging circuit which may have an efficiency of anywhere from 60% to 80% - thus the overall- total efficiency is the product of these efficiencies and ends up being 45 to 68%." - http://xtronics.com/reference/batterap.htm and to back up Capt. Howdy: "9. Will a high output alternator damage an OPTIMA battery? No, not as long as the voltage is properly regulated. OPTIMA's exceptionally low internal resistance means it will accept higher current more efficiently than conventional batteries." - http://www.1st-optima-batteries.com/faq.asp#2 I was wrong about an alternator not running all the time, and I apologize to Matt Ion: "Charging System Basics: As long as the engine is running, all of the power for the accessories is delivered by the alternator. The battery is actually a load on the charging system. The only time that the battery would supply power with the engine running is when the current capacity of the alternator is exceeded or when engine is at a very low idle. " - http://www.bcae1.com/charging.htm In my experience as an installer, I have found that most people that have voltage issues even with caps are running too small of a power wire in the first place. The voltage drop from an undersized wire in turn creates an amperage spike and causes the lights to dim. I have proven this to several customers by increasing the wire size and showing them better results than capacitors. I think capacitors have their place in car audio. In SPL competitions where engine RPM over 2,000 can disqualify you, and with people that listen to country and rock mostly, where the cap has a chance to recharge before the next beat. I don't think everyone needs one, I think that everyone thinks they need one, and that is why they sell so well, but I believe it is almost a scam. >> If your idling, a cap has a tremendous advantage. A bigger alternator >> is not going to make much difference, unless its [quoted text clipped - 8 lines] >used in competition car audio for that one note. It became a fad, and >now everyone uses them. An bigger alternator will have a greater output at idle, but its useless when your trying to put out any major power. One mentioned a major fact in caps, alternators and batteries. The battery will not output any major power until the voltage drops to near 12 volts. The cap will be the most important piece at this time. Lower capacitance caps usually have lower ESR, so multiple small caps will be better than a big one. bussing is not the best method unless you form a star patteren around the amplifier input. If the manufacturer of the cap does not quote ESR, then the capacitance has little meaning. greg > "The power cap, usually 1 or 2 farads, is connected in parallel >between the battery and the amplifier. Multiple capacitors can be [quoted text clipped - 52 lines] >they need one, and that is why they sell so well, but I believe it is >almost a scam. > I have a 1/2 farad cap sitting right next to me that I took out of a car 15 > months ago. It is still reading 10.5 volts. What happens if you lay your tongue across the terminals? How do you know those are *real* volts and not just residual or "phantom" volts? -dan > > I have a 1/2 farad cap sitting right next to me that I took out of a car 15 > > months ago. It is still reading 10.5 volts. > > What happens if you lay your tongue across the terminals? How do you > know those are > *real* volts and not just residual or "phantom" volts? OK, I'm holding the cap with one hand and typing with the other. I'm now slowly raising the cap to my mouth and tongue. Alright, here goes..... AGHHHHHHH!!!!!!!! OK, in all seriousness I DID take a short length of wire and shorted the poles. There was a pretty significant spark. On my tongue, it would have surely hurt. This somehow reminds me of a very old SNL running gag: "Don't you just hate it when....your tongue touches the positive and negative terminals of a fully charged capacitor?" "Oh yah, I HATE it when that happens". MOSFET Positive to negative terminal discharge via discharge resistor. Most all digital caps have built-in circuitry intended to drain it once input power is removed. They also have built-in circuitry intended to charge slow if the cap has input power and a charge of less then 10 volts. This seems to be the fact of the cap in question as stated by the poster that the cap starts flashing it's display at 10 volts (dead give away). Almost forgot it might also have a over-voltage protection circuit and a polarity protection circuit. However a basic non digital cap can hold full charge up to a year without voltage loss, so I read some where a long time ago. >> That's not going to work. as soon as the cap is disconnected it will drain in > [quoted text clipped - 4 lines] >A *good* capacitor should hold a charge almost indefinitely, unless it's got >built-in circuitry INTENDED to drain it. > Positive to negative terminal discharge via discharge resistor. Most all > digital caps have built-in circuitry intended to drain it once input power is [quoted text clipped - 3 lines] > it's display at 10 volts (dead give away). Almost forgot it might also have a > over-voltage protection circuit and a polarity protection circuit. Okay, fair enough... but even a built-in discharge shouldn't be enough to drain the battery overnight. If the battery was that far gone, it would be giving issues even with the cap disconnected. > However a basic non digital cap can hold full charge up to a year without > voltage loss, so I read some where a long time ago. Assuming no leakage, any capacitor can hold a charge indefinitely. And just to be technically correct, there is no such thing as a "digital capacitor". The "digital" is part of the surrounding package; the CAPACITOR itself is the same as any other. No not over night, weeks or months yeah. >Okay, fair enough... but even a built-in discharge shouldn't be enough to drain > >the battery overnight. If the battery was that far gone, it would be giving >issues even with the cap disconnected. They do lose charge over a long time. >Assuming no leakage, any capacitor can hold a charge indefinitely. True the digital display is an add-on and in most cases is removable on most round style caps . There are only two types of car audio power caps that I have seen, The old round ones and the newer ones that sort of look like amplifiers. >And just to be technically correct, there is no such thing as a "digital >capacitor". The "digital" is part of the surrounding package; the CAPACITOR >itself is the same as any other. > They do lose charge over a long time. > >>Assuming no leakage, any capacitor can hold a charge indefinitely. Yes, because of leakage in the dielectric. Notice I said "assuming no leakage". Yeah but LOL, nothing stores power indefinitely with a one time charge, nothing that I can think of. >> They do lose charge over a long time. >> >>>Assuming no leakage, any capacitor can hold a charge indefinitely. > >Yes, because of leakage in the dielectric. Notice I said "assuming no > leakage". > Yeah but LOL, nothing stores power indefinitely with a one time charge, > nothing that I can think of. That's because nothing is 100% efficient, or in this case, leak-proof. ASSUMING a capacitor could be COMPLETELY LEAK-FREE, it would hold its charge indefinitely. >>>They do lose charge over a long time. >>> >>>>Assuming no leakage, any capacitor can hold a charge indefinitely. >> >>Yes, because of leakage in the dielectric. Notice I said "assuming no >>leakage". > ASSUMING a capacitor could be COMPLETELY LEAK-FREE, it would hold its charge > indefinitely. Which is kinda like saying "Assuming that sharks don't eat meat, you're perfectly safe swimming in a tank of hungry sharks." These kind of statements make for nice theoretical chit-chat and might impress your EE professors, but in the imperfect world in which we live, sharks *do* eat meat and caps do leak, making "assuming a round cow" statements something less than useful in trying to diagnose problems. -dan Weill, as soneone asked this question before yall long talk, Yes my ca Voltage meter is on when i leave my car and It Does turn off after 1 seconds of no voltage change. That Morning when i entered my car, noticed my meter on it was blinking a "10" meaning its UNDER 10volts ( know i didnt leave anything on besides my Radar. That was the firs time it had ever happened. I Reinstalled it today PROPERLY with resistor size of 1K Ohm and as of right now its working perfectly fine I'll give updates on how it goes. Thanks for the info/hel -- jimbo_limited Here's a possible guess at your problem. I use one of those newer fancy caps with the LED voltage top and even some extra blue lights they added beyond that. Whenever the voltage changes, they come on for about 10 seconds. Perhaps yours are not turning off at all. This would CERTAINLY drain your battery after a week. In other words, if you do have an LED voltage display, is it on when you first go out to your car BEFORE you start it up or turn the key? If so, that's likely your problem. MOSFET > > There was another thread about this but my problem is slightly > > different. [quoted text clipped - 41 lines] > out, the cap is charged - you can then remove the bulb and connect the power > directly. |
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