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Car Forum / Honda Cars / December 2006Battery cable came off!
Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard the idle sound change: it seemed higher. I stepped on the gas a bit, and I heard a soft electrical "pop" near the stereo panel. I hurriedly shut down the engine, I found that the negative battery cable had come off! (It had a quick-release connection). I connected it, restarted and found everything working fine, even checked all the stereo functions, LEDs, and the ECU. I've read that the battery acts as a big capacitor to smooth out voltage spikes. The entire episode didn't take more that 10 seconds, but I'm worried... could there be any permanent damage? > Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard > the idle sound change: it seemed higher. I stepped on the gas a bit, [quoted text clipped - 7 lines] > voltage spikes. The entire episode didn't take more that 10 seconds, > but I'm worried... could there be any permanent damage? For an event like that, the damage will be clear immediately. The only electrical zaps I've seen delayed failures on were lightning strikes. I've dealt with about two dozen lightning strikes (one on a bizjet, the rest at communication sites) and have come to the conclusion that although the failure rate drops off after 6 months the equipment is often never completely right again. Sounds like you dodged the bullet. Congratulations! Mike > Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard > the idle sound change: it seemed higher. I stepped on the gas a bit, [quoted text clipped - 7 lines] > voltage spikes. The entire episode didn't take more that 10 seconds, > but I'm worried... could there be any permanent damage? You read wrong. The battery reacts too slowly to absorb spikes, it lives at 12V versus your alternator's typical 13.5-14.5V, your alternator wouldn't produce a spike unless it failed spectacularly, and having the terminal come off wouldn't cause a spike either. Ultimately, cars have batteries for one purpose: starting the engine. Once the engine is running, the alternator provides for all the car's power requirements. Yes, batteries are also used to power accessories when the car is off, but the only reason they're there in the first place is to crank the starter. >> Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard >> the idle sound change: it seemed higher. I stepped on the gas a bit, [quoted text clipped - 12 lines] > alternator wouldn't produce a spike unless it failed spectacularly, > and having the terminal come off wouldn't cause a spike either. It absolutely would. Damage may not always occur, but there will be spikes. The battery's secondary function IS to provide a buffer for the alternator's pulses. Connecting the cables together without the battery in between is dangerous to the car and should NOT be done. You could to that n 1976, but not now. http://www.uuhome.de/william.darden/carfaq2.htm > Ultimately, cars have batteries for one purpose: starting the engine. > Once the engine is running, the alternator provides for all the car's > power requirements. > Yes, batteries are also used to power accessories when the car is > off, but the > only reason they're there in the first place is to crank the starter. See the above link.  SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ >>> Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard >>> the idle sound change: it seemed higher. I stepped on the gas a bit, [quoted text clipped - 31 lines] > > See the above link. To clarify;the alternator generates AC voltage which is rectified to pulsating DC,and the ONLY thing that smooths it to reasonably pure DC is the battery. Otherwise,your car radio would be buzzing in tune with the engine RPM. SignatureJim Yanik jyanik at kua.net >>>Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard >>>the idle sound change: it seemed higher. I stepped on the gas a bit, [quoted text clipped - 14 lines] > > It absolutely would. Damage may not always occur, but there will be spikes. Fair enough - a SIGNIFICANT spike. > The battery's secondary function IS to provide a buffer for the > alternator's pulses. And pray, how does it do that? It's not a voltage regulator, it's not a capacitor. Internal resistance limits how quickly it can react to voltage changes. > Connecting the cables together without the battery in > between is dangerous to the car and should NOT be done. You mean the battery cables? Yeah, that'll fry your alternator in a hurry, since you're basically shorting its output. > You could to that n 1976, but not now. I wouldn't even try it in a '76. > http://www.uuhome.de/william.darden/carfaq2.htm > [quoted text clipped - 6 lines] > > See the above link. See the phrase "IN THE FIRST PLACE" in my above paragraph. Of the four uses Darden lists for the battery, I've already noted the first and fourth above... for the second ("filter and stabilize") it can only do so much - there's still ripple in the voltage measured even with the battery, as the charging voltage is usually well above the battery's voltage... as for the third, if the battery is really needing to "provide extra power" while running, then the charging system is under-rated to begin with, and the battery is acting as a band-aid. > >>>Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard > >>>the idle sound change: it seemed higher. I stepped on the gas a bit, [quoted text clipped - 23 lines] > capacitor. Internal resistance limits how quickly it can react to voltage > changes. Uh, the battery is nothing more thann a large capacitor. Capacitors are the main components of voltage "smoothing." You know, like radio noise suppression etc. JT > Uh, the battery is nothing more thann a large capacitor. Actually, they're not. Capacitors /store/ electrical energy. Batteries /create/ it via a chemical reaction. Charging a battery is not storing energy; it's (to oversimplify) merely reversing the checmical reaction. > > Uh, the battery is nothing more thann a large capacitor. > > Actually, they're not. Capacitors /store/ electrical energy. Batteries > /create/ it via a chemical reaction. Charging a battery is not storing energy; > it's (to oversimplify) merely reversing the checmical reaction. Technically yes, but both smooth voltage.. JT >>>Uh, the battery is nothing more thann a large capacitor. >> [quoted text clipped - 3 lines] > > Technically yes, but both smooth voltage.. Batteries do, to a degree. That's not what they're designed for though. >>>>Uh, the battery is nothing more thann a large capacitor. >>> [quoted text clipped - 7 lines] > Batteries do, to a degree. That's not what they're designed for > though. But it's one of the things they're *used* for. Do you want to email Bill Darden and tell him he's wrong? SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ >>>>>Uh, the battery is nothing more thann a large capacitor. >>>> [quoted text clipped - 11 lines] > > Do you want to email Bill Darden and tell him he's wrong? I didn't say he was wrong. >> Uh, the battery is nothing more thann a large capacitor. > > Actually, they're not. Capacitors /store/ electrical energy. Batteries > /create/ it via a chemical reaction. Charging a battery is not storing > energy; it's (to oversimplify) merely reversing the checmical reaction. Batteries most definitely do have capacitance, do you have a meter? Batteries most definitely do store energy when charged. Or are you suggesting that when it is used up that more is created out of nothing? >>> Uh, the battery is nothing more thann a large capacitor. >> >> Actually, they're not. Capacitors /store/ electrical energy. Batteries >> /create/ it via a chemical reaction. Charging a battery is not storing >> energy; it's (to oversimplify) merely reversing the checmical reaction. >Batteries most definitely do have capacitance, do you have a meter? >Batteries most definitely do store energy when charged. Or are you >suggesting that when it is used up that more is created out of nothing? Capacitors are electrostatic while batteries are electrochemical. A capacitor capable of storing the energy within a car battery and power capability needed to start a car would be the size of a double long semi. >>>> Uh, the battery is nothing more thann a large capacitor. >>> [quoted text clipped - 10 lines] > A capacitor capable of storing the energy within a car battery and power > capability needed to start a car would be the size of a double long semi. True, but nobody is suggesting that you start your car with a capacitor. At issue was the batteries ability to absorb spikes from the alternator. Given that, batteries do have capacitance. I don't know how much it should be to be effective though, but its there. >>>Uh, the battery is nothing more thann a large capacitor. >> [quoted text clipped - 3 lines] > > Batteries most definitely do have capacitance, do you have a meter? Sure they do. A pair of wires running side-by-side do too. Not enough to consider them functional "capacitors" though. > Batteries most definitely do store energy when charged. Or are you > suggesting that when it is used up that more is created out of nothing? Yes, they store energy... but not ELECTRICAL energy. That's generated out of a chemical reaction. >>>>Uh, the battery is nothing more thann a large capacitor. >>> [quoted text clipped - 7 lines] > Sure they do. A pair of wires running side-by-side do too. Not enough > to consider them functional "capacitors" though. I've seen such a "pair of wires" literally used in a electronic circuit for a capacitor,by DESIGN. Engineers modeling components like a battery for computer aided design,the battery model definitely has capacitance. Even the electronic symbol for a battery is two plates,just like a capacitor. >> Batteries most definitely do store energy when charged. Or are you >> suggesting that when it is used up that more is created out of >> nothing? > > Yes, they store energy... but not ELECTRICAL energy. yes,it is electrical energy. What other sort of energy would it be? > That's generated > out of a chemical reaction. differing from electric charges generated by friction;static electricity. They both are ELECTRIC charges,though.Both are electric current,too. SignatureJim Yanik jyanik at kua.net >>>>>Uh, the battery is nothing more thann a large capacitor. >>>> [quoted text clipped - 10 lines] > I've seen such a "pair of wires" literally used in a electronic circuit for > a capacitor,by DESIGN. Sure, usually in RF circuits where very tiny amounts of capacitance are needed. Sometimes a "capacitor" even exists as just a pair of interlaced traces on the circuit board. And in high-frequency designs, particularly network cables, the inherent capacitance of the wires must be taken into account. That doesn't mean a pair of wires *are* "a capacitor", or that in most cases the inherent capacitance is of any concern or use, any more than the capacitance in a lead-acid battery is of any concern or any real use. > Engineers modeling components like a battery for computer aided design,the > battery model definitely has capacitance. > Even the electronic symbol for a battery is two plates,just like a > capacitor. Well, usually a series of stacked plates of alternating lengths. But that's true of the the symbol for ANY battery, including your good old carbon-based flashlight batteries. >>>Batteries most definitely do store energy when charged. Or are you >>>suggesting that when it is used up that more is created out of [quoted text clipped - 3 lines] > > yes,it is electrical energy. What other sort of energy would it be? They don't STORE electrical energy. When you charge a battery, the electrical (kinetic) energy you feed into it creates a chemical reaction; the electrical energy is converted to chemical (potential) energy. When not charging, the inverse chemical reaction converts chemical energy back to electrical energy. In a very simpistic sense, sure, a battery is "storing" electricity (as opposed to "electrical energy"). At the physics level, it's merely converting one form of energy to another. >>>>>>Uh, the battery is nothing more thann a large capacitor. >>>>> [quoted text clipped - 50 lines] > (as opposed to "electrical energy"). At the physics level, it's > merely converting one form of energy to another. When you DRAW current from a battery,how does the chemistry knows to start converting chemicals to electric current? Where does that initial current come from? Simple,the *charge on the plates* decreases and the chemical reaction adds more electrons to fill the depletion of the plates charge. SignatureJim Yanik jyanik at kua.net > When you DRAW current from a battery,how does the chemistry knows to start > converting chemicals to electric current? > Where does that initial current come from? > > Simple,the *charge on the plates* decreases and the chemical reaction adds > more electrons to fill the depletion of the plates charge. Very good, you get a gold star. I think this is getting pretty far afield. Does anybody feel the alternator would be stable under varying load with the battery disconnected? Mike > I think this is getting pretty far afield. Does anybody feel the alternator > would be stable under varying load with the battery disconnected? Pretty sure it would, yup, because I once had to drive without one for a week (manual tranny, obviously - you get really adept at finding even the slightest grades to park on). > I think this is getting pretty far afield. Does anybody feel the alternator > would be stable under varying load with the battery disconnected? Thanks for bringing it back, mike. I've been reading all the posts very closely. Anyway, as an update, no delayed effects yet, thankfully. Though I'm not willing to repeat the "experiment" anytime soon: Seems like I have a shorted rectifier in the alternator. (Does this mean that I'm getting voltage spikes all the time?) I'm wondering if the battery is now "absorbing" the spikes, so it seems to boil down again to whether the battery is acting as a large capacitor.. Thanks again to everyone. > Anyway, as an update, no delayed effects yet, thankfully. Though I'm > not willing to repeat the "experiment" anytime soon: Seems like I have [quoted text clipped - 4 lines] > > Thanks again to everyone. In my experience, yes, you can expect to be getting ripple of about 1/2 volt to 1 volt even with the battery connected. It should be measurable with a DVM on AC voltage setting, measuring across the battery with the engine running. If diodes in two phases (out of the three phases most alternators use) fail the AC voltage can be over 1 1/2 volts with the battery connected. On an oscilloscope it looks pretty radical. With one phase out the voltage hangs around 14 volts and drops when the bad phase is called on to put out. With two phases out the voltage hangs around 12 volts and spikes upward. Mike >> Anyway, as an update, no delayed effects yet, thankfully. Though I'm >> not willing to repeat the "experiment" anytime soon: Seems like I [quoted text clipped - 16 lines] > > Mike Applying AC straight from one phase of the alternator's output would harm the battery,causing excessive heating.On one-half of a cycle,the battery would charge just like the other phase outputs,but on the 2nd half cycle,it would discharge(thru the ALT),maybe even provide a path for damaging currents to be drawn from the battery.It depends on whether the diode failed open or short/leaky. Open failure would just remove that phase winding's output,lowering the alternator's total output current,and giving more ripple. SignatureJim Yanik jyanik at kua.net >I think this is getting pretty far afield. Does anybody feel the alternator >would be stable under varying load with the battery disconnected? > >Mike test >> Uh, the battery is nothing more thann a large capacitor. > > Actually, they're not. Capacitors /store/ electrical energy. > Batteries /create/ it via a chemical reaction. Charging a battery is > not storing energy; it's (to oversimplify) merely reversing the > checmical reaction. The plates of a battery have capacitance. They are charged by the chemical reaction. SignatureJim Yanik jyanik at kua.net I feel like Kerry... "What I meant to say is, 'Uh, the battery is nothing more than THE EQUIVALENT of a large capacitor.'" I think that it's time for a belt of Pinch! JT > >> Uh, the battery is nothing more thann a large capacitor. > > [quoted text clipped - 11 lines] > at > kua.net > >> Uh, the battery is nothing more thann a large capacitor. > > [quoted text clipped - 5 lines] > The plates of a battery have capacitance. > They are charged by the chemical reaction. A car battery has many farads of capacitance. In other words, it's a very stout capacitor.. MK >>>>Uh, the battery is nothing more thann a large capacitor. >>> [quoted text clipped - 8 lines] > A car battery has many farads of capacitance. In other words, > it's a very stout capacitor.. Not even close. The smaller the plates of a capacitor, the less the capacitance. The further apart they are, the less the capacitance. Lead-acid battery plates are EXTREMELY small and EXTREMELY far apart compared to a true capacitor's. If you were to drain the water from a battery and measure the capacitance, I suspect you'd find it in the low microfarads, if not picofarads. > >>>>Uh, the battery is nothing more thann a large capacitor. > >>> [quoted text clipped - 16 lines] > If you were to drain the water from a battery and measure the capacitance, I > suspect you'd find it in the low microfarads, if not picofarads. Sure. The capacitance I mention is more of an apparant capacitance. It's not true capacitance per say, but the normal operating car battery does provide a large apparant capacitance to the system. But this would not be the case with a non functioning battery. I use car and deep cycle marine batteries to run radios here in the house. My chargers are unfiltered, but yet I have little noise to my radios. The use of my battery as a cap is a bit different in operation vs a true capacitor, but the final apparant filtering is still there. If the battery were not acting as a cap of sorts, I would have hash and trash out the kazoo.. I don't know if this makes any sense, as it's hard for me to describe stuff like this off the top of my head.. As a quite dangerous test you could try running a car radio off the running alternator with no battery connected. I bet it will be quite noisy, fairly unregulated as far as volume, etc vs rpm. IE: if the rpm dropped too low, the radio might totally drop out due to the low voltage. Hook the battery up, and all is smoothed out. Both as far as regulation, and also filtering. If thats not acting like a large "apparent" capacitor, I don't know what is. The operation is different, but the end results are about the same. This is not something I've really thought about too much, but I've always considered the usual operating car battery to have many farads of capacitance, at least as far as overall function. Maybe not true in the strict sense, as far as true caps go, but as far as the end results of placing it in the system. I dunno if this makes any sense or not.. :/ MK > >> Uh, the battery is nothing more thann a large capacitor. > > [quoted text clipped - 5 lines] > The plates of a battery have capacitance. > They are charged by the chemical reaction. A car battery has many farads of capacitance. In other words, it's a very stout capacitor.. MK I'm happy to be wrong on this one, Matt. Thanks, guys. *Whew*. Mike: Lightning strikes, really? Wow. > I'm happy to be wrong on this one, Matt. Thanks, guys. *Whew*. > > Mike: Lightning strikes, really? Wow. I've taken two direct strikes to my antenna mast in the last 5 years. No damage at all. But...I ground out my feedlines when storms are in the area. The strikes hit about 15 ft from where I'm sitting at this puter. I was sitting here both times. My mast is very well grounded, with low resistance. When a strike hits that mast, it's very quiet. Sounds about like a light bulb being thrown on the ground, and then a loud sonic boom directly overhead. Pretty wild.. But I have no trouble at all. My puter doesn't even flinch. You can set the station up for full time use, even with direct strikes, "all broadcast stations are set up this way", but it takes a detailed installation using a ground bulkhead, careful single point grounding, suppressors, etc, etc.. I'm too cheap and lazy to mess with all that. :/ I just manually ground the feedlines at the bulkhead. As far as the car, yes, it's not good to unhook the alternator while running. You got lucky. Many cars would have done a toasting of the alternator in record time. You dodged the bullet this time it seems. If it did have a problem from doing that, it will usually be blown diodes I would think. MK > I'm happy to be wrong on this one, Matt. Thanks, guys. *Whew*. > > Mike: Lightning strikes, really? Wow. Yep - mostly mountaintop sites, two or three a year since I moved to the mountains. For some reason the storms prefer holidays and my anniversary! Mike >> I'm happy to be wrong on this one, Matt. Thanks, guys. *Whew*. >> [quoted text clipped - 4 lines] > > Mike Try Central Florida,the lightning capital of the US. Also,the power density of Florida strikes are on average twice that of northern lightning strikes. I've had a pine tree about 300 ft from my apartment(tallest in the area) get struck(and killed) while I was watching. The bolt travelled right down the side,blowing a channel of bark off the tree. It took out a surge protector on my phone line and my modem,didn't harm the phones or the TeleZapper. SignatureJim Yanik jyanik at kua.net >> Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard >> the idle sound change: it seemed higher. I stepped on the gas a bit, [quoted text clipped - 18 lines] > the car is off, but the only reason they're there in the first place is to > crank the starter. The problem is that alternators are very inductive. Without a battery, changes in current produce wild fluctuations in voltage; suddenly reducing the current draw by half should roughly double the voltage for a moment. At low current I would expect the alternator and regulator to go into oscillation without a battery to stabilize it. Mike The battery does as Jim said. But another condition called load dump could have created a destructive transient. Load dump is defined by the ISO to be as large as 270 volts on the 12 volt system. SGS Thompson defines it as 80 to 100 volts. But then better automobiles are designed with electronics that make load dump not destructive. Of course when you connect a computer to the car using a discount inverter, does it have load dump protection - or did you just save some pennies? The damage, if it occurred, would be complete in milliseconds. Apparently you did not suffer load dump damage. But you, like many others who replied here, should know of load dump and what automotive electronics (properly constructed) cost more money. > Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard > the idle sound change: it seemed higher. I stepped on the gas a bit, [quoted text clipped - 7 lines] > voltage spikes. The entire episode didn't take more that 10 seconds, > but I'm worried... could there be any permanent damage? |
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