12V Battery charging problem - MASSIVE SPARKS

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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!!
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On 12/22/2015 6:08 PM, snipped-for-privacy@unlisted.moc wrote:

If you have a GENERATOR instead of an ALTERNATOR, it's possible for the thing to get polarized backwards and charge your battery backwards.
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mike wrote:

Did OP put in a new generator then?
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wrote:

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.
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wrote:

explain why he has low cranking power as a reverse charged battery does not produce as much current output as a properly charged battery.
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On Wed, 23 Dec 2015 15:15:24 -0500, snipped-for-privacy@snyder.on.ca wrote:

If the battery was reverse charged wouldn't the starter be turning backwards???
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On 12/26/2015 6:16 PM, >>>Ashton Crusher wrote:

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+1
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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.
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On 12/23/2015 1:06 AM, snipped-for-privacy@unlisted.moc wrote:

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.
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On 12/23/2015 3:06 AM, snipped-for-privacy@unlisted.moc wrote:

I've worked with lead acid batteries for 38 years and have never heard of one getting reversed polarity.
I do know that in one connects a battery to a generator however, it will simply re-polarize and work.
I'm wondering if the battery is somehow mislabeled?
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YOUR CHARGER MOST BE ISOLATED FROM THE TRACTORS FRAME. (99 to 1) THAT CHARGER IS CHASSE FRAME NEGATIVE THERE FOR YOU WILL HAVE DIRECT SHORT.
"philo" wrote in message wrote:

I've worked with lead acid batteries for 38 years and have never heard of one getting reversed polarity.
I do know that in one connects a battery to a generator however, it will simply re-polarize and work.
I'm wondering if the battery is somehow mislabeled?
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about. The problem has been found. It was as I suspected - the battery was charged backwards and the generator was flashed to be neg ground - so when connecting the charger "correctly" it was actually connected backwards and was seen by the battery as a dead short.
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On 12/23/2015 3:27 PM, Tony944 wrote:

Even though I never heard of a battery having reversed polarity I Googled and found that if a battery is totally discharged then reverse charged...the polarity can in fact reverse... so I learned something.
My feeling is that it's unlikely it was mis-marked at the factory
so I guess I'd discharge the battery , the properly charge it and see if it wills till hold a charge
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I googled "12 volt battery has reversed polarity" (without the quotes) and got a lot of information. This seems to be more common than I thought. I never knew it could happen, or even thought it was possible. After the initial sparks, I was very puzzled. I double and triple chcked the connections and markings on battery. I put the charger on a board, thinking that maybe it's case was grounded. I removed one cable, then both, (going to the tractor), then got a different charger, which I first tested on another battery.
At this point, I walked away from the tractor, scratched my head, and spent a good hour trying to make sense of this. I even called a friend who is a auto mechanic, and he said he did not know what was going on, but asked me if I had a bad extension cord plugged into an outlet which was touching the tractor. I told him I was touching the tractor and would have known that quickly, not to mention the outlet I have is a GFI.
All of a sudden I began to think that "maybe..... somehow....." that battery had reversed it's polarity. I grabbed my VOM meter, and sure as shit, it was reversed. That's when I googled the (above).
This URL was real helpful. http://www.batterystuff.com/blog/battery-myth-can-a-battery-reverse-polarity.html
--

Anyhow, I bought this tractor a few months ago, and I ran it for many
hours, and thoroughly tested it, while looking for anything needing
  Click to see the full signature.
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On 12/23/2015 7:27 PM, snipped-for-privacy@unlisted.moc wrote:

Yep
38 years in the business and I never saw anything like that.
Way back a million years ago I put the battery in my 53 Chevy backwards but the generator just repolarized.
The ammeter read backwards and the gas gauge pegged negatively but nothing was harmed
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On 12/23/2015 6:05 PM, philo wrote:

What a bunch of youngsters. ;-) Back in 1963, my dad had a TV repair shop. He did some work for a car repair shop. One day he fixed the blown output transistor on a car radio. This was when car radios still had tubes, but they had switched to one transistor in the audio output. Car guy bought it back...It's broke. Fixed it again. Car guy brought it back...IT'S BROKE!!! Fixed it again. This time Dad and I went over to the shop and measured the battery. Was charged backwards.
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I remember those old tube car radios with a power transistor output. I know that anything with transistors wont tolerate reversed power. It just burns up the transistor(s). Modern electronics that operate on batteries (Cell type, like AA AAA C D), generally have a diode or more to prevent burning up the device because it's too easy to put in batteries backwards.
If my tractor has a transistorized radio, or electronic ignition module, it/they would be fried now. But I dont have any of that.....
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On 12/23/2015 8:26 PM, mike wrote:

Very interesting
BTW: My '53 Chevy (3100 truck) had a radio that must have been put in later. It ran off a vibrator and reversed battery polarity did not matter
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transistor. It was an 'all tube" radio - most definitely- back in '53
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