12V Battery charging problem - MASSIVE SPARKS

[Paintedcow]

I have a farm tractor with a positive ground. I hooked a 15A battery charger to it, and had massive sparks shooting all over the place. Yes, I did connect the polarity correctly, with the red clip on the batt + post and black one in the batt - post.

Because of this, I removed one of the battery cables (to the tractor)[the negative one], and reconnected the charger. The sparks were so intense, they melted a small hole at the top of the battery post.

In all the years I have charged auto batteries, I have never had this happen. Even touching the clips together on the charger dont cause such intense sparks. What the heck could cause this? My first thought is a shorted battery, but the tractor lights work fine. There just is not enough charge to turn the starter over fast enough to start the engine. I would think that if the battery was 'dead shorted' it would not operate the lights, or make the starter turn slowly.

To insure the charger is not defective, I connected it to another battery and it's charging properly, on both the 2A and the 15A settings.

Anyone have any clue what's happening. I sure dont!!

[mike]

Did you actually measure the battery voltage?? If you have a GENERATOR instead of an ALTERNATOR, it's possible for the thing to get polarized backwards and charge your battery backwards.

[Tony Hwang]

Maybe your battery has internal short?

[rbowman]

This is a long shot. Do you have a meter to verify the positive terminal is in fact positive? It's rare but it is possible to reverse the polarity on a discharged battery by connecting it backwards.

It's the farm tractor part that makes me suspicious:

Like I said, it's a long shot that the entire system might have been reversed.

[Paintedcow]

If your Erection has lasted more than 4 hours.......

You've spent too may hours with your Priest !!!

Go Home to your wife, and your erection will go away!

[M. Stradbury]

That would do it.

[bob_villain]

The sparks he is describing could not be produced by his 15 Amp charger! The arcing is from the battery somehow...Mike may be correct.

[clare]

Or the battery has been charged backwards by a reverse polarized generator. Sure sounds like the charger is connected backwards to the battery

[Tony Hwang]

Did OP put in a new generator then?

[Micky]

Don't you mean to say that it's possible to change the polarity of a generator (not an alternator) by connecting the battery backwards, even for a short time?

At any rate, you're right about the meter. He should measure the voltage of the battery without the charger, with the charger, without the charger when cranking the starter motor.

If low charge, or a bad battery, is really the problem, the voltage will drop too much when cranking the starter.

(With a car, I don't need a meter and don't need to get out of the driver's seat by trying to blow the horn while cranking the engine. I do this test when the car won't crank. If it doesn't blow well, it's the battery. It if blows well, the starter isn't even engaging electrically, so its the starter circuit or the sstarter.)

Yeah, a gnerator. Not a battery.

That only works if the battery is reversed, connected backwards. Maybe it is and the OP is going by the post positions, which are reversed, so he should look at the embossed + and - next to the battery posts. Those are always accurate.

[Micky]

I don't think so. It could lower a 12v battery to 10 volts or less, but a 12 volt charger woldn't spark that much tryhing to charge a battery that was putting back 8 or 10 volts.

Anyhow, he should get a meter and measure the voltages.

[Paintedcow]

Yes, I think you're right. I took my VOM meter and hooked it up, the battery *IS* backwards. The terminal marked + is now NEGATIVE, and the one marked - is now POSITIVE. I triple checked the meter leads, and the battery markings. It definitely is backwards, and reads about 11.5 volts.

Yes, it DOES have a generator.

I knew there was some sort of polarity issues with generators. I did NOT know a battery could reverse polarity. In fact I cant see how that could occur without destroying the battery, burning up wiring, or damaging something else.

I suppose this could have occurred when I had the battery disconnected for awhile, while I was replacing all the bad wiring to the lights.

This tractor might have an alternator by the time I finish this repair. I only had one vehicle (my first car) with a generator, and I remember having a big hassle with the generator system in that car, and finally having to get a mechanic to fix it. Of course back then, I did not know much about auto repair. But this is bringing back some bad memories about those damn generators. Almost all old farm tractors have had their generators replaced with alternators, but not this one. I think it's time! It's easy to wire an alternator in place of the generator, but not so easy to mount the alternator to fit the space and get the fan belt to work properly.

[Paintedcow]

As I said in a prior reply, YES, the entire system appears to have reversed. It may be rare, but it did it. My VOM meter proves the battery is reversed. Your URL link explains well how to get the polarity set right, (and I vaguely recall doing this many years ago on my first car), but how do I get the battery reversed again? -OR- do I just reverse the leads on the battery? Or maybe I'll have to replace it. (It was a good battery).

Now I know why they quit using generators. This one will be replaced with an alternator real soon. When I bought this tractor, it ran well and did not have any major problems. I knew the wiring to the lights was chopped off at the switch because of bad wires, and there were a few other minor issues, but just seeing that generator gave me a sick feeling. (now I know why). Almost every antique tractor still in use has been converted to an alternator and NEG ground. But not this one, it still has the POS ground too. This will be converted soon, if not immediately.

[Paintedcow]

It looks like we have an idiot are at play here, using other people's user names, and posting using some unknown newsreader called News Rover

21.0.1.

But I guess when you live in some slum in Central Texas, have no friends or social life, belong to a religious cult, and are not capable of getting an erection, you spend all your time on newsgroups stalking people and posting off topic rubbish!

Oh well, back to regular programming.....

[Paintedcow]

I have a pretty good thing going on in this newsgroup. I contribute a lot and I get along with everyone really well. I don't want it to end. It feels good to talk about things with other people who share my interests. I help others when I can. And other people help me when they can. It feels good. I want things to stay as they are right now. But only time will tell.

[Stormin Mormon]

I'm pleased with the assorted wisdom here. I'd never heard of reverse polarity, and battery charged backwards. Amazing, the things that go on, out in the world.

Did you actually paint a cow? I've heard of farmers spray painting the word "cow" during hunting season when the Citidiots are out with guns. And, yes, I've heard of citidiots harvesting a cow when they hold a deer hunting permit.

[mike]

My first rule is, "if it ain't broke, don't fix it."

Depends on your objective. Your motivation may be different if you are gonna keep/use it instead of fixing it up for sale. Are you gonna run it at night with lots of lights?

First thing I'd do is see if you can get the lid off the regulator to see if it got smoked in the process of reversing the battery. Replace the battery, polarize the generator and see how much current it puts out.

Watch the voltage vs engine speed with all the loads on and see if it's likely to do what you want.

Check the generator brushes while you're at it. Another thing is to measure the battery current drain with everything off. Carbon tracks and other leakage paths need to be fixed.

You only need an alternator if your usage patterns prevent the generator from keeping up.

[Tekkie®]

[e-mail] posted for all of us...

+1 He finally admitted he f'd it up when he had it disconnected earlier.

[clare]

Not necessarilly. If the battery went dead at some point and it had trouble charging someone may have "flashed" the generator in reverse so although it LOOKS to be pos ground it could really be negative. He needs to test with a voltmeter to be 100% sure.

[clare]

Reverse polarization and charging the attery backwards would also explain why he has low cranking power as a reverse charged battery does not produce as much current output as a properly charged battery.