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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / June 2006Weird intermittent flat battery problem
Normally my battery starts my car first time every time - as it has every day for the past seven years. However three times over the past couple of months, the battery has been dead: although there's enough power to light the ignition light, as soon as I try to start the engine, the ignition light dims almost to extinction and the engine barely turns over. Each time, as soon as I've jump-started the car from a neighbour's car, there's enough power in the battery to restart the engine, within just a minute or so. The outside temperature was about 15-20 deg C (about 60-70 deg F) so it's not related to the effect of freezing-cold weather on the battery or on the viscosity of the engine oil. I've had the battery tested at three different garages and they all say that it's holding its charge well and doesn't appear to have a dead/dying cell, and the voltage with the engine running appears to show that the alternator is charging the battery. The battery is about 3 years old. One garage said that if the battery really had been dead enough not to turn the engine over (eg if I'd left my headlights on overnight), it would have taken about half an hour of running to charge it enough to operate the starter motor. They said the fact that even just a minute or so after jump-starting, the battery is able to start the engine unaided suggests that it was never flat in the first place! The car has a diesel engine, so there will be quite a large current drawn by the glow plugs in addition to that drawn by the starter motor. Also diesel engines are harder to turn over. However the battery is correctly rated for a diesel engine. I've put an ammeter in series with the battery and with nothing turned on (and the car door closed to turn the courtesy light off!) I can't detect any current flow. The courtesy light draws about 500 mA (correct for a 6W bulb) and the sidelights draw about 2A (correct for 4x 6W bulbs). In case it's relevant, the car is a 1999 Peugeot 306 HDi. I'm reluctant to change the battery unless this really is the cause. Can anyone offer any suggestions? I would clean the battery cables first. Don't forget that the cables have 2 ends... A corroded connection on one of those cables can cause intermittent troubles like you are seeing. 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) > Normally my battery starts my car first time every time - as it has every > day for the past seven years. [quoted text clipped - 38 lines] > I'm reluctant to change the battery unless this really is the cause. Can > anyone offer any suggestions? A little better explanation. As the plates in the grid detiorate over the years, conductive material builds at the bottom of the battery. When it gets deep enough to touch the bottom of the grid, and cause a conductive connection between two plates, those two are effectively shorted. The battery can't do much in this condition, there isn't correct continuity within it. When the battery is moved, the debris will sometimes resettle and the battery will suddenly come to life... Same with charging, the current applied to the battery causes an overloading of the sediment connection, overloading it and causing it to fail, like a fuse. The battery is now in correct condition, and will test as if it is fully charged and fine. This can sometimes lead to explosions on jumpstarting when you produce an arc, as shorting produces loads of hydrogen sulfide gas, so don't fart around with it...replace it  Signaturejeffcoslacker http://www.automotiveforums.com jeffcoslacker wrote in message jeffcoslacker.29rfrd@no-mx.nodomain.com: > A little better explanation. > [quoted text clipped - 14 lines] > an arc, as shorting produces loads of hydrogen sulfide gas, so don't > fart around with it...replace it OK. I can see how this sediment could produce an intermittent problem. Presumably the sedimentation will build up when the car is not used for a few days, and then will be dispersed either due to the vibration of driving or by the act of charging it when the engine is running. I presume that the formation of sediment is irreversable. When I jump start, I always attach the final terminal of the jump leads at the donor battery rather than the dead battery in case hydrogen [*] is produced at the dead battery which an arc could ignite. Interesting that none of the garages or car-spares places that I've taken the car to have mentioned about sediment. You'd think they would have done, if they'd been aware of the concept, since it's in their interest to try and sell me a new battery. Unfortunately the battery is a sealed type (doesn't need distilled water adding to the electrolyte) so there's no way that a garage could test the electrolyte to see if there are traces of sediment, to confirm if this is the problem. However you've convinced me that the battery is dying, if not actually dead yet. I'll have to go out and buy a new battery - "only" £70 (about $110). And this time I'll go for one with a warranty that lasts for more than 2 years ;-) [*] I *think* it's hydrogen rather than hydrogen sulphide - the latter is instantly detectable (by the nose!) and I don't think it's flammable. But I could be wrong. > jeffcoslacker wrote in message > jeffcoslacker.29rfrd@no-mx.nodomain.com: [quoted text clipped - 44 lines] > instantly detectable (by the nose!) and I don't think it's flammable. But I > could be wrong. Both recent replies to your post are good information. Sediment intermittently shorting out cells is a very rare occurrence but it does happen. Corroded terminals on the other hand are quite common and both will cause the symptoms you described. My suggestion would be to buy a new battery and clean all the battery cable connections. Then you will be done with it and can have piece of mind knowing that the problem has been fixed. BTW, you are correct in assuming that sediment problems can not be corrected with out rebuilding the battery. SignatureKevin Mouton Automotive Technology Instructor "If women don't find you handsome, they should at least find you handy" Red Green >> jeffcoslacker wrote in message >> jeffcoslacker.29rfrd@no-mx.nodomain.com: [quoted text clipped - 65 lines] > corrected > with out rebuilding the battery. OK, Kevin, another wild/theoretical question: I've never done it, but have heard once in a half-century (+) of working on cars that such a battery can be placed in a paint-shaker & shaken "back to life". I assume from your replies that you are too much a pro to revert to such a tactic; however, have you ever heard of such? s > >> jeffcoslacker wrote in message > >> jeffcoslacker.29rfrd@no-mx.nodomain.com: [quoted text clipped - 71 lines] > replies that you are too much a pro to revert to such a tactic; however, > have you ever heard of such? s HA HA HA! Thirty years ago my Dad used to empty out old batteries, fill them with water, shake the sediment out, rinse them again several times then refill with electrolyte. Every now and then one would actually work and have another year or two of useful life. Of course that was back when batteries were twice their present size and the plates were a lot thicker and spaced farther apart. Modern batteries are ultra compact and have plates as thin as paper. Shaking one up usually breaks up the plates and makes the condition even worse. Guess you wouldn't have anything to loose by trying it, but don't get your hopes up, and be careful of acid and explosive gassing. SignatureKevin Mouton Automotive Technology Instructor "If women don't find you handsome, they should at least find you handy" Red Green >> >> jeffcoslacker wrote in message >> >> jeffcoslacker.29rfrd@no-mx.nodomain.com: [quoted text clipped - 102 lines] > even worse. Guess you wouldn't have anything to loose by trying it, but > don't get your hopes up, and be careful of acid and explosive gassing. Actually, I was trying to tempt YOU into this experiment!!! sam > OK, Kevin, another wild/theoretical question: I've never done it, but >have heard once in a half-century (+) of working on cars that such a battery >can be placed in a paint-shaker & shaken "back to life". I assume from your >replies that you are too much a pro to revert to such a tactic; however, >have you ever heard of such? s Don't laugh. I've seen a 10+ year old battery still going strong in an identical environment where they would previously last 2. How? A silly little device that "shocks" the battery. Basically, the concept is to keep the plates clean by stunning it with high voltage. It unloads a capacitor to overcharge the battery for a split second. I would have been inclined to add this to the list of automotive snake oils if I didn't know the highly qualified tech dealing with the fleet of vehicles they were testing this on. So, shaking it may have the same effect, supposing you could shake it hard enough..... Let me know how that works out for you, huh? Me, I'm too lazy. I run them until they die, then buy a new one..... We have a battery desulfator here that seems to work well. It's a small power supply that generates a square wave of a voltage considerably higher than the battery voltage, but very brief and of a high frequency. The thing is connected to a tired battery and left there for a week or two, and the effect is to break up the sulfate that has accumulated on and around the plates and get it back into solution. We've rejuvenated a few aircraft batteries with it as well as car batteries. That said, my experience has usually been that starting problems are much more often due to bad connections. If the lights are dimming when trying to crank on a supposedly good battery, it's battery, solenoid or ground connections. They might look OK but the crap shows up only after the connection is taken apart. Battery cables will corrode inside the battery clamp itself, out of sight. Dan <snipped posting> You can also try a desulfator such as Pulsetech, Batteryminder (or Battery Minder), Solarigizer, and other pulse desulfators and oils and chemicals such as the ones by Battery Doctors. These pulse desulfator devices, in my opinion, however, dry out the batteries prematurely, causing shorter life than normal, which is not stated in manufacturer's review or consumer reviews. > We have a battery desulfator here that seems to work well. It's > a small power supply that generates a square wave of a voltage [quoted text clipped - 12 lines] > > Dan >jeffcoslacker wrote in message >jeffcoslacker.29rfrd@no-mx.nodomain.com: [quoted text clipped - 44 lines] >instantly detectable (by the nose!) and I don't think it's flammable. But I >could be wrong. Hi Martin, I couple of quick points. The last connection when jump starting should be to ground away from the battery because the will be a small arc and you are trying not to ignite the hydrogen gas produced during charging. Please see Section 6 in the Car and Deep Cycle Battery FAQ on www.batteryfaq.org for more information about jump starting. The second point is that hydrogen is flammable when it is exceeds 4% concentration when mixed with air. Please see Section 14.4. Normally wet "Maintenance Free" batteries only have a two year or less average life in hot climates because you can not replace lost water and their overall service life is reduced with deep discharges. Please see Section 7.1.3. Kindest regards, BiLL...... I still suggest, just buy a new battery and save the grief, LOL. SignatureKnifeblade_03 http://www.automotiveforums.com |
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