Hi all, Seeking help ... I got into my 97 Chrysler Cirrus -- when unlocking it, the automatic door locks sounded "funny" as they unlocked -- and when I went to start the car, nothing. No instrument lights, ignition turnover, or anything. The illuminated ring around the ignition blinks, as does the dome lights, when I try to start the car, but those are the only electrical components that seem to light up or respond. Everything else is dead. I thought it might be the battery, but I don't even get a "dead battery" sound of fading power or any sort of turnover. It's like everything is locked up, so to speak. Whatcha think? Alternator is gone? The transmission has been a big sluggish lately, but no other problems... Help? Thanks! BEM
You won't normally - because the problems this causes are long term. Keep in mind that semiconductors are really no different than the filament in an electric light bulb. Every time they are turned on there is a tiny surge of power. Over time this wears them out until eventually the material breaks down. The process is accelerated by heat as well. Now, normally the lifetime of most semicondutors in most circuits is tens to hundreds of years. But when you pull your battery disconnection trick and subject your auto electronics to a large chunk of electronic noise and massive surge caused by pulling the battery out, it is pretty hard on the circuitry and shortens it's life. The shortening may possibly only decrease a component from a normal lifespan of 70 years to 65 years, still much longer than the vehicle lifespan, but you also might get unlucky and have a component that happens to be substandard due to manufacturing defect get booted over the edge. And another thing, this trick doesen't tell anything about the condition of the diodes, nor the power output of the alternator. You can have a failed diode in the alternator and still produce enough power to keep the car running under normal circumstances, but not enough to keep the battery changed during periods of heavy power draw. The best way for the DIYer to handle this kind of problem is if he has any question about the alternator at all, just yank it out and go to his local auto parts store who can bench test the alternator. And if the battery is more than 3 year old, just replace it, don't even screw around trying to test it. New batteries are cheap, and most car batteries don't last more than 5 years anyway. And automotive batteries can fail in all sorts of weird ways, some of which are NOT detectible with the standard "battery tester" behind the parts counter. For example, a battery can have a low grade short and it will charge up fine on a battery charger, and even produce enough power to pass a load test, but you let it sit 48 hours and at the end it will be stone dead. Incidentally, this is why I'll never buy a Sears Diehard again for the rest of my life, I had one of those do this to me, and the Sears service guy wouldn't replace it even after I demanded it because his battery tester claimed it was good, as a result I got cheated out of a warranty on it. (and to rub salt in the wound, the mechanic I took the car to later and who confirmed my diagnosis, charged $100 for a new battery!) Ted
Wow. So many grossly inaccurate responses in one thread. The classic: disconnecting a battery while car is running. Ted comes close to explaining that this is wrong - but provides incorrect reasoning. That disconnect recommendation could create load dump - a voltage spike of between 50 and 200 volts on 12 volt electronics - depending on which auto industry standard is consulted. You need a 3.5 digit multimeter. Measure battery voltage after car has not run for a long time. It probably measures much less than 12 volts. Get the car jump started. Measure voltage while running - without heavy electrical load applied. Should measure about or just above 13 volts. Now turn on every heavy load - high beams, rear window defogger, fans etc. Voltage should remain near or above 13 volts. No 13 volts means alternator system is defective. Low voltage under load means either belts are discretely slipping OR "alternator, regulator, whatever" system is defective. Turn off car. Leaving high beams on. If battery voltage drops in minutes to or below 12.0 volts, then battery is defective. Simple with proper tools and basic knowledge. But even Ted provided defective information. Semiconductors do not wear out. Even the idea that power cycling light bulbs causes premature failure - a myth not supported by any technical facts. Light bulb life expectancy is predominately due to voltage applied and hours of operation - or mechanical shock when powered. Get that multimeter. No one responsible does electrical work without one. Some are so irresponsible as to recommend disconnecting the battery while car is running - only because it worked for him. A classic example of junk science reasoning. Responsible posters recommend something only after they understand underlying theory AND demonstrate same by experience. That disconnecting battery is a classic example of an irresponsible post. Poster probably never heard of load dump - and the potential destruction of all automotive electronics. Never - never - never disconnect a battery while alternator is charging.
Wow! You asked a simple question and got Einsteinian answers in return. Let me see if I can make this a little simpler for you. You have a six year old battery in your car. It's dead. Buy another. I cannot guarantee it will fix your problem but there is, in my estimation, at least a 95% chance that it will. The person who suggested the battery connections may be correct. But six years is a long life for a battery. Our '96 Town and Country goes through them every few years here in Silicon Valley. The Mazda Miata with it's gel battery went six or seven. It's the battery, Mom. Regards, Ken
My 94 Concorde 3.3L had a failed battery in 98 (just 2 months after I bought the car new). Fortunately my dealer came good for a replacement battery at no charge but that one lasted just 4 years (Exide). The two batteries failed in very different ways: The original factory one died with no warning on a summer day when we stopped at a grocery store for 40 minutes ... when we came out with groceries the car would not even turn over. With a boost we were on our way, but it would not even turn over the engine upon turning off the car after a 15-minute highway run. The dealer determined it was a total failure. Four years later when the Exide battery failed, it went gradually with lots of signs of increasing weakness until it would barely restart the car. I fortunately had a good battery in another car I was about to scrap and it cured the problem with no need for anything but clamp the replacement in place several months ago. As for the comment on the Sears Diehard battery, I had a similar problem with one over a decade ago that was only a year old. It was in a standard car (fortunately, because I had to push start it for several days). I went back to Sears 3 times and they gave me the same song and dance that the battery was fine and that I likely needed other charging components. Being a technician with a few smarts, I knew they were lying and finally took matters into my own hands by turning the "load" knob on the Sear's mechanic's battery tester he had connected to my battery on the 3rd visit. I saw the gauges all crash violently to "0 volts" as soon as I turned the dial .... I had him! ... he finally admitted to the battery was bad and pro-rated me a replacement. Sometimes you just got to catch them in their own scams! Needless to say I buy my batteries at a "real" battery shop these days (I look for the shops that sell "blem" batteries and got my last quality one for under $80 CND. over 4 years ago ... that's the one in my Concorde now) Stuart (Ontario)
"...and massive surge caused by pulling the battery out..." Is what I said and was exactly what you said here. I think you assumed the rest of my post was an attempt to explain why a "load dump" AKA surge, occurs. It wasn't, I was attempting to explain why surges damage semiconductors a whole lot faster than "normal" usage. You should also note that Bill Putney already listed a massive surge yesterday as a problem, even used the same terminology you did. (load dump) Many people have this incorrect idea that semiconductors are the same as fuses, this is wrong. A fuse is designed to burn through almost instantainously. Semiconductors by contrast can stand short overvoltages - but those will shorten their lives. This is absolutely, completely, totally wrong. Entropy occurs in everything. First of all, semiconductors DO wear out. It may take hundreds of years if the semiconductor is operated in a tremendously derated fashion as most are, but they will wear out. There is a physical reason for this, it is because as electrons move through the semiconductor, they generate tiny amounts of heat. Over a long period of time the heat will cause random moves of molecules across the semiconductor joint. Once enough molecules move, the joint is ruined and that is that. This is why if you remove a heatsink from a high power modern computer CPU and run it flat out until it stops functioning, it will be permanently ruined, it will never be stable again. The joints there are so small that once enough heat builds up, it takes little time for the material to be permanently altered. People talk about "burning out" semiconductors (like diodes in alternators) but this is in fact sloppy slang, burning is an oxidization process, and yes some semiconductors can be ruined this way, but most "burned out" semiconductors don't burn, they suffer massive material changes due to excess heat caused by overvoltage, or simply because of too much electricity moving through the material. TO repeat, in most electronics, the process takes many years because the semiconductor joint is so gigantic that there are trillions of molecules of material there, and molecular migration happens to such a small number of molecules that usually the device built around the semiconductor will have long since disintegrated before the semiconductor is seriously degraded. But in many cases, such as overvoltage, overheating, and otherwise operating a device out of it's specs, the process is drastically speeded up. And this process also crops up as a problem if high precision is involved. This is why radio transmitters must be periodically retuned, and why high precision test instruments must be recertified, it is because their use over time will slightly alter their readings, as the semiconductors in them wear. High precision electronic test instruments all have recalibration controls (well at least good quality ones do) that allow them to be recalibrated to a standard. And as far as the lightbulb thing goes, yes it is true that the hours of operation of a light bulb filament are more important to it's lifespan than the number of on-off transitions. You are right in that this example of mine wasn't really accurate. Put it down to trying to shorten a more complicated explanation, which as a nitpicker you obviously are demanding, so I'll spell it out here. Light bulb filaments do wear out, for the same reasons semiconductors wear out - molecular migration of the tungsten metal (or whatever metal is used in the filament) from the filament to elsewhere. Inside a light bulb of course, that "elsewhere" is the inside glass wall of the bulb itself. In a light bulb the process is of course much faster because so much more heat is produced that the molecules are all moving around a lot faster. What I was trying to get at, though, is that they typically blow when turned on due to the surge of current that happens then. The reason there is a surge then is that when the filament is cold, it's resistance is lower, thus more current with the same applied voltage. Obviously if you had a lightbulb on 24 hours a day, 365 days a year, without any surges or overvoltages going through it, it's filament would last longer than one that is turned off and back on a few times a day, and tests will bear this out. But eventually enough material will migrate that the filament will lose structural integrity, sag, and break under it's own weight. It's also a classic example of someone figuring out a shortcut that is destructive to the device in question, but not in a way that is immediately obvious to the customer. It is much the same thing as when people doing body work on a car don't bang out the dent as far as it can be banged out, and instead mold and build up huge chunks of Bondo. It's the same thing as the mechanic that loses a screw because of piss poor fastner control, and figured "they won't see that it's missing and there's lots other screws around it" which is one of my pet peeves. Ted
Semiconductor do 'wear out'. But once we apply numbers to that trend, then "who cares?". In reality, the only thing that destroys semiconductors is the equivalence of "going over the edge of a cliff". You can put a semiconductor on the cliff edge and it will not fail. But exceed specific parameters, and the failure is catastrophic. Ted was describing why load dump occurs - when a battery is disconnected while car is running. But it is not numerous stress conditions that destroy a semiconductor. Either that transient voltage from load dump exceeds a parameter and damages semiconductor, OR semiconductor remains fully functional. What is the threshold? How large must the load dump voltage be? That is a function of the semiconductor AND the many components installed just for that load dump problem. Either semiconductors keep working or they are damaged by exceeding specifications. Same applies to light bulbs. Light bulb life expectancy is not a function of number of power cycles. The light bulb in a traffic signal has about same number of hours of operation as the light bulb on 365 days a year. Power cycling only effects light bulbs damaged by normal hours of operation - IOW in its last 13 hours of operation. Light bulb life expectancy was defined in a previous post that includes voltage and hours of operation parameters. Light bulb life expectancy is only shortened by power cycling when speculation (and not manufacturer's data sheets) are used for facts. Original post. Ted is but the few who responded properly to the original posters question. Never disconnect a battery from a running automobile. Want to understand what happens? Go to rec.boats or rec.boats.electronics to learn about damage when batteries were switched over while engine was running. They too suffered load dump problems. Unless you are using same semiconductor for hundreds of years, then the only reason for semiconductor failure is something that exceeds the semiconductor specifications. That is either total failure or no failure. Run an AMD processor without a heatsink. It will not get slower. Either it will survive the experience OR it will totally fail. Do same to an Intel processor and suffer no damage. Why? Intel's even with 486s had internal thermal protection. Either it is damaged or it is not. Ted also has real world experience. Pathetic the mechanic that can't be bothered to install all the screws. If car was properly designed, then all screws were required.
i'm gonna get flamed for this but it still woks and i have yet to spike a puter doing this get a new battery since the factory one's suc!!!!!!!!!!!
hey dingle berry chryslers now have a battery temp sensor and the alt. have clutches so they can and do charge at only 12.5 and 13. volts depending on ambient temp and a couple of other small details i have and will disconnect a battery while running and never had any ill effects all you engineers here say happen to the puters and now that i think of it my boss gives me all the charging system issues because i never wrong and always fix it right his words not mine
The migration thing isn't a theory. Way back when when Thomas Edison first invented the electric light bulb he used carbon filaments. Over time the inside glass of the bulb got blacker and blacker. One of the attempts to stop this from happening was the insertion of a metal plate into the bulb that was connected to the negative side of the bulb (remember, the original electric power systems were DC not AC, Westinghouse was who pushed AC because it could be transformed) with the idea that the carbon molecules would be attracted to the plate instead of the glass. It was during these experiments that they noticed a voltage on the plate and that led to the development of the vacuum tube. Frankly I feel sorry for techs like mic-canic who basically go through their careers working on technology that they only barely understand. I'll bet he has never looked at a power lead in a car using a high speed oscilloscope that can actually trigger on the typical short durations of most spikes. If he's ever seen a scope output it was probably a garbage-grade shop quality one that shows a flat line instead of what's really there. Ted
This is news to me. Or is that a real grin? I thought that tungsten evaoporates off the filament because it gets hot, irrespective of the type of current... DAS
Yeah, like the charging rate. Why is this? Does your shop not have an AVR or is it that you don't know how to use one? And he is????
Haven't heard that one since Junior High... Clutches on the alternator? Uh, no. But Chrysler cars do have voltage regulators with temperature compensation- have had so since, oh, 1972. Automobile computers are extremely well shielded with things like Zener diodes on on the input/output data and driver lines, etc. Its very hard to blow one. On the other hand- pull that battery cable often enough and you may eventually blow one of the zeners. Do it again, and without the zener, the front-end of the computer will go.
you are so predictable neal we have this cool little tester courtesy of d.c and it does it all and will even print out the shabang don't even have to hook up the drb anymore
go look at a 2003 model and notice the black cover on the back of the alt. it's a honest to god centrifgual.clutch and it's directions come from the pcm and the temp compensation is like nothing you know about! because thats only a small part of it's operation.
Really? What was it about me that you predicted? The dealership was billed for that tester, trust me... When was the DRB ever capable of performing a full charging system test, including battery load? Has it occured to you that once you **** up a customers vehicle, they do not return to your miserable establishment for additional punishment, cementing the impression that your methods do no harm?
