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Battery charging error

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by mattb, Apr 28, 2012.

  1. G'day All.

    I charged up a new lead acid battery this evening, which I intend to put in the bike (the Bullet) tomorrow. When placing the charger clamps on I was careful of course to match the charger clamps and battery terminals. I just went out to remove the clamps and...

    ...I clearly wasn't that careful, because I'd fitted the charger's positive clamp to the battery's negative terminal and vice versa!

    The battery sparked when I first fitted the terminal which I thought odd, but I know nothing of such technical things. I had the charger (2.7A car charger) on it for six hours and took it off because nothing was happening and I need to go to bed (I thought it odd that it was taking so long when last time it took 20 minutes on this charger to charge a new battery - the 'power' light was on the whole time but the 'full' light never came on. The battery was cold throughout).

    Using a multimeter test the proper way round (positive to positive, negative to negative), I get 12.25V on the battery; and if I reverse the test (positive to negative on the multimeter to the battery) I get minus 12.25. The battery charger when disconnected now shows the 'full' light permanently and sparks when I touch its connectors to the battery either way, correctly or in reverse.

    So what does this all mean? What is the consequence? Do I simply hook the battery up as normal tomorrow? I'm guessing it ($57) is fine and maybe the charger ($10) is now cactus?
  2. Just pop the charger back on THE CORRECT POLARITY and it'll probably be OK from what you've said.
    The charger itself sounds like it had protection and no damage was done (luckily)
  3. Thanks mate.

    I didn't think to check the charge of the battery before following your advice. But,

    I left it on for twenty minutes and the charge is now 13.06V. I assume that 12hrs after taking it off the charger, and close to 24hrs since acid was put in it, it wouldn't have gained charge on its own.

    The interesting thing regarding the charger is that the 'full' light is on permanently now, even if nothing is hooked up to the charger. It gives a reading of 10.6V when plugged in.

    The old battery in the bike is cactus - it doesn't have any acid in it! Maybe I'll check some water in there and do some before and after tests with my charger to see if the charger itself is working.

    Fortunately this bike is kickstart, so the battery is not so vital, but I am having problems with stalling at idle and would like to be certain that the battery is in good condition so I can trouble shoot the problem.
  4. Hmm. Not sure what's going on here.

    I'm mentally trying to work out which direction the electrons would be trying to go in under various different scenarios and making fairly heavy weather of it.

    However, my suspicion is that the battery is fine. Most of the faults that might damage a battery when on charge would be fairly immediately apparent due to the large quantity of smoke, acid fumes and melted plastic that are likely to result. I suspect that all that happend, as far as the battery is concerned, is that insufficient voltage was applied to its terminals to do anything.

    You mention the charger sparking when connected to the battery terminals. You shouldn't be hooking up a live charger to the battery. Cavalier about safety though I am, this is something I will always try to avoid because it's a recipe for a hydrogen explosion and, at worst, an acid shower. Correct procedure is to hook up the croc clips and then switch on at the wall.

    Just bung the battery in the bike, fire it up and do a rising volt test to make sure your charging circuit is operational. A rising volt test is simple. Just put your voltmeter across the battery terminals with the bike idling and note the reading. Then bring the revs up slowly and you should see the reading increase. All the tests I've done have shown a distinct jump between idle and, say 2000 rpm when the system has been healthy, or a steady reading of not very much at all when it's been a Suzuki :D.

    Incidentally, does the Enfield have an ammeter? An ammeter and the ability to read it can tell you an absolute shitload about the condition of your electrical system and battery. A must have instrument on anything a bit elderly IMHO.

    Couple of observations from personal experience. I have never pre-charged a battery, car or bike, before fitting or use. At least in part this is because I've often been in situations where I haven't been able to. I know current wisdom says that it's a must, but I get long, trouble free lives out of my batteries and have never had an unexpected failure in a battery that I've owned from new, so I remain sceptical.

    On the same note, I've always used tap water for top ups. Again, I know it flies in the face of conventional wisdom, but reliability in service suggests that I'm not doing anything too heinous. Mind you, I haven't had to top up any recent batteries all that much, given the improving manufacturing techniques for the batteries and the increasing sophistication of my vehicles.

    Another idea I consider overrated is the need to gently trickle charge a battery so as not to upset it. Having seen a 60A ammeter go off the scale on a routine basis after cold starting on at least one car I've been involved with, without the battery exploding, melting or meeting a premature end, I'm convinced that lead acid batteries are a lot tougher than they're made out to be and that even the sort of feeble charging system that many bikes have can give them a far harder time than the average $10 buzz box charger ever will.

    From a great many threads on internet forums, I get the impression that under less than perfect conditions (ie the real world of knackered old machinery :D) that many smart chargers won't work. My old buzz box, however, bought for less than a tenner a couple of decades ago and giving a basic, unregulated 14-15V or so has charged everything I've asked it to, including gel-cells and nicads. Admittedly you can't wander off and leave it for a week, though I'm happy to leave it overnight, but it will stick the electrons back into a battery without overthinking the situation.

    Back when I ran old Suzukis I saw more than my fair share of batteries boiled dry. Because I was broke, a long way from potential sources of battery acid and needed to be mobile pronto, I usually just filled the dry battery with tap water. Astonishingly enough, it actually worked and at least one of those sadly abused batteries lasted me nearly another year of all weather, daily use as long as I didn't leave the bike standing for more than a day or two.

    I would emphasise that I don't actually recommend any of the above practices but I have direct personal experience that indicates that they can all be got away with in an emergency with little or no detriment to personnel or equipment.
  5. Thanks Pat. I checked the battery tonight before fitting it, as it's been sitting a couple of days since I followed Ducfreak's advice and just gave it a charge. The batter was sitting at 12.6V. I then fitted it to the bike (haven't started it as its late) and spent a bit of time fixing an electrical problem - turning the bike on for a couple of minutes at a time while doing so - and she seems quite happy. Certainly the electrical system is suddenly much more lively with the new battery (given the old one was dry that's no surprise).

    I have an ammeter. It tends to sit at centre (with it's wild wobble around centre when running) on the old battery.

    I'll be very interested to see whether this effects the problem of the bike stalling easily. With the old battery it certainly wouldn't start with the headlight on, despite being a kick starter, so I take it that the battery is important for starting and so possible for idling on this.... (if not, one thing I love about this bike is how cheap parts are, even good aftermarket bits like better, and unified, R/Rs, as well as new replacement carbs etc)
  6. A good charger will have some protection in to handle reverse polarity connection. A cheaper charger like mine has a fuse that blows (I know it works because I have done the same thing). A crap charger will reverse the polarity of the battery if it does not smoke first!
  7. Even with a kick start, you need enough volts across the coil's primary winding to generate enough oomph across the secondary winding to throw a good, fat spark across the plug electrodes. If the battery is dead, you're relying on your leg to spin the engine fast enough to get the alternator putting out sufficient voltage to achieve that. Worse still, if the battery is dead, the bike's electrical system will try to use all the available electricity to put some charge into it rather than feeding trivia like the ignition system. Similarly, the headlamp will suck away any spare electrons that the battery doesn't guzzle. Given such competition for scarce resources, the coil will see stuff all.

    The only real way to avoid this is to use a magneto, as most bikes once did. Being completely independent of the rest of the electrical system, a magneto will get you home regardless. If it's a good one. Many are not, having been subjected to decades of weather, inexpert maintenance and mechanical butchery.

    As for the ammeter, it should spend most of its life around zero as the electrical loads like igniton and lighting should ideally be perfectly balanced against the rate of charge from the alternator by the rec/reg. A +ve reading indicates that the battery is charging. A -ve reading indicates that it is discharging.

    Normally, with the ignition and lights on but the engine not running you will see a discharge. On starting, this should change to a charge reading as the alternator replaces charge lost while standing, used by lights before starting etc. On an electric start vehicle, this charge rate can be quite frightening (my 60+ Amps experience with a big alternator and a low battery) but something like the Enfield should be a bit more modest. Maybe 5-10 Amps at most. As the battery recovers, the charge rate should gradually drop to zero over a period of, usually, a few minutes. It can take longer if the battery is really low.

    Keeping an eye on your ammeter can tell you:-

    If your rec/reg is stuffed, leading to overcharging (permanent +ve reading).
    If your rec/reg is stuffed leading to undercharging (permanent -ve reading).
    If your heated grips/spotties/kettle/small aluminium smelter etc. require more than the standard alternator's output (-ve reading when all accessories are switched on).
    If your battery is stuffed (permanent +ve reading because it's continually trying to charge or returning to zero reading suspiciously soon after starting).
    When your points open (if you've got points) for timing or starting purposes.

    It's a handy little beastie.
  8. Thanks Pat.

    yes, I'm using the ammeter for starting (leftward deflection indicating I'm beyond TDC). It makes it easy!

    The ammeter sits at centre when cruising along, however at idle it deflects leftwards in a fast waver between center and the middle of -ve, as shown by the red line below.


    The problem I am now having is a tendency to stall at idle (I have to constantly blip the throttle at the lights) and the ammeter is deflecting as described whenever I am thus idling.

    I wouldn't be the first to have rec/reg problems on an Enfield, if that's the problem.
  9. It sounds not so much as if there is a fault, as such, but more as if the electrical loads exceed the alternator's capacity at idle but are adequately catered for when there are a few revs on. Whilst I wouldn't expect this to be a normal situation on a modern bike, not so very many years ago there were plenty of machines around whose charging systems couldn't cope with permanent headlamp use without eventually flattening the battery. Being an older tech bike, it's possible that the Enfield fits into this category.

    Things to check in the meantime, though, are for additional electrical loads over and above standard. Has someone fitted a really tarmac melting headlamp globe in an attempt to see where they're going at night? If so, stick a standard one back in and revise your diet to include more carrots. Maybe consider an LED replacement globe for the rear as well.

    Another thing which can go largely unnoticed on a modern but that can have a huge effect on marginal charging systems is the general state of the electrical system. Check that all connections on the bike are clean and shiny. When you've only got a few watts to play with, wasting any via heat in a dodgy connection can be the difference between reliable service and a daily flat battery.

    Actually, looking at a larger copy of the photo, it looks like it's reading ~-6A at idle. Whilst I wouldn't trust the calibration of the gauge, that's about the right order of magnitude for all the electrical loads I'd expect (basically headlamp, tail lamp and ignition) which suggests that the alternator is producing nothing at idle but doing a reasonable job above that. Might be worth checking the pre rec/reg output of the alternator. Assuming a standard 3-phase permanent magnet alternator, disconnect the three wires coming from the stator, start the bike and, having made sure your voltmeter can cope with AC, measure the voltage between each wire in turn and a suitable earth (eg engine case) with the engine idling. All three should be roughly the same and should exceed 12V. If it won't idle on the batttery alone, try disconnecting the headlamp. If one is low, your stator has lost a phase and needs rewinding or replacing. If they're all low, you're faced with three possibilities.

    1) It's designed that way.
    2) All the stator phases are shot.
    3) If it's a permanent magnet unit the rotor has lost magnetisation. There are people (don't know who though) who can remagnetise rotors.

    It could be a rec/reg failure, but, in my experience, that generally results in no charging at all, or so much charge that the battery boils, which you will notice if you have any sense of smell at all.
  10. Thanks Pat. I cannot get onto this straight away but I will follow your advice regarding those tests in the coming weeks.