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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / October 2006Battery dies in car
Anybody got any ideas about where to start looking for a problem where a good battery goes dead in a matter of a few hours setting my car? 1988 Taurus. Runs great, all fuses intact, just draws battery down real fast. Thanks! >Anybody got any ideas about where to start looking for a problem where a >good battery goes dead in a matter of a few hours setting my car? 1988 >Taurus. Runs great, all fuses intact, just draws battery down real fast. Put ammeter on battery. Watch the load. Start pulling fuses out until the load goes away. Check whatever is on that fuse. If the fuses are all pulled out and the load is still there, start looking at anything on fusible links. Feel around for cabling that is warm. A clamp-on DC ammeter makes this a lot easier, but you can always just disconnect the ground strap and put an ammeter in series with it. The clamp-on meter, though, makes it much easier once you've started to track it down because you can just clamp it on any line and check the current. Note that most clamp-on ammeters can't handle DC, but an auto electrical shop will have one right handy. --scott  Signature"C'est un Nagra. C'est suisse, et tres, tres precis." Good advice! Thanks much! It worked. And what does the end statement mean? Good advice! Thanks much! It worked. And what does the end statement mean? > Good advice! Thanks much! It worked. And what does the end statement > mean? Clamp on DC ammeters are normally used at high loads. They are not so accurate at low current draws. AC current is much easier to measure with a clamp on meter. It isn't impossible to measure DC this way, but the equipment tends to be inaccurate, or very expensive. >Clamp on DC ammeters are normally used at high loads. They are not >so accurate at low current draws. [quoted text clipped - 3 lines] >It isn't impossible to measure DC this way, but the equipment tends >to be inaccurate, or very expensive. It's getting better. You can get a meter in the $250 range which are accurate down to 1/10 amp or so. That's not anywhere good enough to find trickle leaks, but it's good enough to find something that discharges the battery in a day. The things are a lot better than they were five years ago. They are still no replacement for a real shunt ammeter, though. The neat thing about the new meters is the auto-nulling. You hold the thing in position, press the zero button, then put the wire in and read the display. If you're careful about keeping it in the same position, you're compensating for any magnetic leakage into the thing. --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." > It's getting better. You can get a meter in the $250 range which are > accurate down to 1/10 amp or so. That's not anywhere good enough to [quoted text clipped - 9 lines] > you're compensating for any magnetic leakage into the thing. > --scott Yes, I think it has improved significantly. I was looking for a reasonably accurate clamp on meter about a year ago, and at that time the DC performance just wasn't good enough, at least for the cheaper units. I finally just rigged an calibrated inline shunt with a millivoltmeter and it worked fine. >>Clamp on DC ammeters are normally used at high loads. They are not >>so accurate at low current draws. [quoted text clipped - 6 lines] > It's getting better. You can get a meter in the $250 range which are > accurate down to 1/10 amp or so. And my experience with those meters (at work, where we have a number of different brands) is that they're ONLY accurate to that level if you re-set the zero level every 10 minutes or so (no kidding). Also, if there's ANY audio-frequency to radio-frequency noise in the line you're measuring, such as AC ripple from an alternator, it can throw the reading way off even if you zero carefully just before measuring. >And my experience with those meters (at work, where we have a number of >different brands) is that they're ONLY accurate to that level if you >re-set the zero level every 10 minutes or so (no kidding). No, no. You have to reset the zero level EVERY time you take a measurement. Don't wait ten minutes. Even if the meter doesn't drift, the field around it might very well be drifting. >Also, if >there's ANY audio-frequency to radio-frequency noise in the line you're >measuring, such as AC ripple from an alternator, it can throw the >reading way off even if you zero carefully just before measuring. Depends on the meter, but it's true. I find the Fluke one at work with true RMS measurement is much better in this regard than the $250 Extech cheapie. Even so, it's very easy to switch over to AC mode and see how much ripple you've got. I first got one of these things a decade ago to measure projection arc systems that were in the 50 to 200 amp range, and they were very flaky and temperamental with a lot of hand-nulling required and constant drift. They're now good enough to measure smaller currents and a lot faster to null, but they're not perfect. Still faster than disconnecting a cable in most cases. --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." Scott Dorsey Wrote: > >Anybody got any ideas about where to start looking for a problem where > a [quoted text clipped - 21 lines] > -- > "C'est un Nagra. C'est suisse, et tres, tres precis." I would like to add another senario here even though the OP fixed his problem. http://www.automotiveforums.com/vbulletin/showthread.php?t=515601 Ciao SignatureDieInterim http://www.automotiveforums.com >http://www.automotiveforums.com/vbulletin/showthread.php?t=515601 > >Ciao Excellent DieInterim. I'll do this test tonight. My problem is my alternator light comes on sometimes, the power to run the heater fan isn't there. Then it goes out and the car comes *alive* again with full output. I think if there is a bad diode, then this is a permanent situation, not intermittent as my situation is. My battery checks out OK. My cables seem to be fine. Except that when it isn't getting charged, of course it gets run down. Turning the engine OFF and then restarting corrects the alternator light, temporarily. Then sometimes it comes back on anyhow. Lg > >http://www.automotiveforums.com/vbulletin/showthread.php?t=515601 > > [quoted text clipped - 12 lines] > > Lg I am confused as to where this post started from, but you are giving a text book example of a polished up fan belt. I test them by taking a cold off engine and seeing if I can hand slip the alternator pulley. If I can, the belt is dead. An alternator takes a few HP to spin up under load and if it will hand slip it will not charge properly. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) >> >http://www.automotiveforums.com/vbulletin/showthread.php?t=515601 >> > [quoted text clipped - 20 lines] >a few HP to spin up under load and if it will hand slip it will not >charge properly. I have a serpentine belt, and it is not glazed. It grips like a tiger. Also, the belt tensioner is working correctly. The problem has been fixed. It was a poor electrical connection at the alternator VR even though the plug was mechanically sound and inserted all the way. Wiggling the wires going into the plug revealed the fault. My fans are electrically powered; there are two of them right behind the radiator. Lg >http://www.automotiveforums.com/vbulletin/showthread.php?t=515601 > >Ciao Excellent DieInterim. I'll do this test tonight. My problem is my alternator light comes on sometimes, the power to run the heater fan isn't there. Then it goes out and the car comes *alive* again with full output. I think if there is a bad diode, then this is a permanent situation, not intermittent as my situation is. My battery checks out OK. My cables seem to be fine. Except that when it isn't getting charged, of course it gets run down. Turning the engine OFF and then restarting corrects the alternator light, temporarily. Then sometimes it comes back on anyhow. Lg ============================================================ leakage between battery and alternator is measured 93 _micro_ amperes. i.e. 0.093 milliamperes. verdict: acceptable >Anybody got any ideas about where to start looking for a problem where a >good battery goes dead in a matter of a few hours setting my car? 1988 >Taurus. Runs great, all fuses intact, just draws battery down real fast. >Thanks! does the car even charge the battery? Put a voltmeter on the battery, rev the engine a bit. The voltage should read 14.4V +/- .5V. Measuring a parasitic load might be rather difficult to the beginner with limted electronic experience. A meter to be used for this purpose can be purchased very cheap. It will be somewhat necessary to troubleshoot this prob tho. Let us know if u need help hooking it up. There is an old trick that is just as effective, and doesn't require the use of an ammeter. Obtain a tail light bullb #1157. Disonnect neg bat terminal. Connect one end of light bulb to the cable end, and the other end of the light bulb to the negative battery terminal itself. Key should be in off position. The light bulb should not be lit. More than likely it will be if there is a problem with parasitic draw. If the light is on, proceed as indicated by Scott Dorsey to find the bad circuit. When a fuse is pulled and the light goes out,prob is found. None of these procedures should be tried until,like Az Nomad said, Charging voltage is verified and determined to be good. Good Luck! Jim > Anybody got any ideas about where to start looking for a problem where a > good battery goes dead in a matter of a few hours setting my car? 1988 > Taurus. Runs great, all fuses intact, just draws battery down real fast. > Thanks! Two main possibilities. One- battery is bad. Two, current drain somewhere. Not likely to be an actual short- a short would create smoke, run battery down in minutes. To test battery, you need a voltmeter. These are getting very cheap these days. Even a digital voltmeter, usually quite accurate, can be had for less than old analog meters used to cost. With fresh, FULL charge on battery, put voltmeter directly across battery terminals. Should read about 12.5 volts. Now turn on headlights. Voltage should drop no more than a volt. If it drops SEVERAL volts, it is likely you have a bad battery. If it is not the battery, but a moderate current drain, this is quite hard to diagnose without more equipment. Pulling fuses one at a time- wait a day, repeat, is one low cost option. Yep, could very well be a bad battery. > If it is not the battery, but a moderate current drain, this is quite > hard to diagnose without more equipment. Pulling fuses one at a time- > wait a day, repeat, is one low cost option. I have had a long running war with my Reatta, which is 'mostly', won, but I have the occasional lost battle with it. That car is full of dark ages electronics and modules. Occasionally, it just doesn't seem to shut down all systems, and the battery may go flat. Just about when I start trusting it, and it may be months between occasions, it goes off on a drunk. Looking through JC Whitney this morning, I noticed a couple of master disconnect switches which could be helpful. But they are not cheap, about $25. If I installed one of those, then when I chose to trust parking the car at the airport for a week, I could disconnect the battery from the total system. And, it would make an ideal place to insert an ammeter for the occasional bit of trouble shooting. In this way, the ammeter could be shunted into place before opening the disconnect switch, and all systems would remain in their existing state. I may work on this a little. I love the Reatta, but she is like being married to an unfaithful woman...she may reform, and she may recur. >> If it is not the battery, but a moderate current drain, this is quite >> hard to diagnose without more equipment. Pulling fuses one at a time- [quoted text clipped - 21 lines] >married >to an unfaithful woman...she may reform, and she may recur. Take it one step further. I would like to not only have an ammeter but also a digital voltmeter, giving me readings -all- the time. In real time. What I get instead is an IDIOT LIGHT on the dashboard, which tells me that the alternator took a dump. But it won't come on for intermittents. It comes on only when the thing is outputting zero current. If it is outputting less than what should be coming from it, then no idiot light. this is unsatisfactory imo. OTOH, if I screw with the vehicle in any way, I've voided my warranty. Which places me between a rock and a hard place as far as *mods* are concerned. Lg I like GLicks answer on the ammeter. Just like an unfaithful woman, one day you'll catch it :) . 25 for a switch isnt expensive for one of that rating. Marine stores carry them too. I have one on my boat for two batteries , batt one on, batt two, on, both on, both off. You might have a sticky relay or defintely something thats not shutting off when it should. Were the weather conditions the same during all these failures? Ya gotta figure the battery is a power supply device and the only way you'll actually fix it is to monitor what its doing and hopefull wont have a fire in the process waiting. >>> If it is not the battery, but a moderate current drain, this is quite >>> hard to diagnose without more equipment. Pulling fuses one at a time- [quoted text clipped - 36 lines] > > Lg > > Take it one step further. I would like to not only have an ammeter > > but also a digital voltmeter, giving me readings -all- the time. In [quoted text clipped - 3 lines] > > current. If it is outputting less than what should be coming from it, > > then no idiot light. That ammeter will need to be a digital one with good sensitivity at the lower end. A typical 60-amp analog ammeter isn't going to register the 1 amp or less that drains a battery over time. Dan >> > Take it one step further. I would like to not only have an ammeter >> > but also a digital voltmeter, giving me readings -all- the time. In [quoted text clipped - 9 lines] > > Dan my parasitic drain after the GEM module turns off is 11 milliamperes. I suppose that I could disconnect the battery for long term storage, but the car gets used too much for that. Lg "Lawrence Glickman" > my parasitic drain after the GEM module turns off is 11 milliamperes. > > I suppose that I could disconnect the battery for long term storage, > but the car gets used too much for that. > > Lg 11 ma is not much drain, but as you say upon long storage it could flatten a battery. I bought a couple of battery disconnect switches for my cars, so that if I have to leave them at the airport for a month, I cut all the drain off. Also, there is the chance that some crappo electrical component comes alive at times and drains the battery. I had this happen on an 89 Buick Regal and it almost drove me nuts. I finally found that the seat belt retractor relay would sometimes come on at night, maybe when it was very cold, and the battery would be flat the next morning. When I disconnected the battery during the night, of course, no problem. Finally I caught the car in one of its infidelities, and quickly found the relay problem. >"Lawrence Glickman" >> [quoted text clipped - 19 lines] >during the night, of course, no problem. Finally I caught the car in one of >its infidelities, and quickly found the relay problem. I thought about a knife-switch disconnect for the B+, but because there is Zero Room between my battery and the engine hood, I would have to splice in an *ordinary* knife switch somewhere in that red cable. That means I would have to build an insulated enclosure in the engine compartment, put the knife switch in there...too much trouble, and one more connector I have to worry about. Of course, in your situation where the vehicle is parked "at the airport for a month," no question I would take the wires off the battery terminals. Both of them to be on the safe side. I think if I left my battery in the vehicle for a month, the thing would be dead when I went to start the car. Even in the Dealer Showroom, for this exact vehicle I bought off the showroom floor, when I looked under the hood they had one of the cables disconnected. Unless you live in Sunshine Country where it doesn't snow and you have a lot of daylight, then you can use a solar panel. But I rather park inside a garage rather than on the roof, and I keep my car in a garage, so a lot of good that would do me. Lg > I thought about a knife-switch disconnect for the B+, but because > there is Zero Room between my battery and the engine hood, I would [quoted text clipped - 8 lines] > left my battery in the vehicle for a month, the thing would be dead > when I went to start the car. The problem with disconnecting the battery on newer cars: the ECU loses its internal memory and the engine runs like a toilet for a while after starting again while it figures out all the stuff it forgot, unless we have non-volatile memories in these things now? I don't know. My old Ford F150 sure didn't like being disconnected. And any security system won't work, either. > Even in the Dealer Showroom, for this exact vehicle I bought off the > showroom floor, when I looked under the hood they had one of the > cables disconnected. That might be a fire-regulation safety thing, or just to keep the dome/hood/trunk lights from killing the battery, since they might be left open a lot. Dan >> I thought about a knife-switch disconnect for the B+, but because >> there is Zero Room between my battery and the engine hood, I would [quoted text clipped - 8 lines] >> left my battery in the vehicle for a month, the thing would be dead >> when I went to start the car. ============================================================== > The problem with disconnecting the battery on newer cars: the >ECU loses its internal memory and the engine runs like a toilet for a >while after starting again while it figures out all the stuff it >forgot, unless we have non-volatile memories in these things now? My 2003 Ford sedan rides fine after the battery has been disconnected. I've had it disconnected a number of times already. It does not run like its in the toilet. I don't know if the memory is non-volatile or not, but suspect it -is- volatile. Anyhow, all that's going on is the PCM is learning the right fuel/air mixes and possibly shifting points for the tranny. Let me put it this way. I've got 2 identical vehicles ( same as mine ). One has had a battery disconnected The other has had the battery continuously in circuit. You wouldn't be able to tell which was which. > I >don't know. My old Ford F150 sure didn't like being disconnected. > And any security system won't work, either. Security system didn't work? You're not driving anywhere without a battery. As soon as you reconnect the battery, the security system is activated. >> Even in the Dealer Showroom, for this exact vehicle I bought off the >> showroom floor, when I looked under the hood they had one of the [quoted text clipped - 3 lines] >dome/hood/trunk lights from killing the battery, since they might be >left open a lot. possibly. Makes me wonder about all the cars on the Dealership's lot. They have hundreds of cars out there on the lot. Imagine having to worry about their batteries dying until a buyer comes along. I'm sure they have at least one wire disconnected. Lg Not usually. My father used to work for a dealer that disconnected battireies on the showroom floor, but that was to keep dome light drain from killing the battery. Cars in inventory were not disconnected. If a battery did run down, they would simply hook up a charger and recharge it. Roy >>> I thought about a knife-switch disconnect for the B+, but because >>> there is Zero Room between my battery and the engine hood, I would [quoted text clipped - 51 lines] > > Lg >Not usually. My father used to work for a dealer that disconnected >battireies on the showroom floor, but that was to keep dome light drain from >killing the battery. Cars in inventory were not disconnected. If a battery >did run down, they would simply hook up a charger and recharge it. >Roy What a PITA that must be. You've maybe got hundreds of vehicles sitting on a lot, rusting away, batteries draining down, waiting for a customer to rescue the vehicle before it goes to $hit. If you just wait for the batteries to run down on their own, you chance sulfiding of the plates, and then you're talking money. The customer's money of course. The customer ends up paying for _everything_, including the Salemsan's daughter's piano lessons. Lg >>>> I thought about a knife-switch disconnect for the B+, but because >>>> there is Zero Room between my battery and the engine hood, I would [quoted text clipped - 51 lines] >> >> Lg |
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