Battery polarity
I have a curious case of a 1926 Essex, where the battery was connected negative ground, yet my meter showed it as positive ground. The owner left the ignition on, and the battery went flat. When he put his battery charger on it blew the fuse, so he reversed the connections (+ to - and - to+) and the battery charged up in the opposite polarity to what is was meant to be. I inspected the car, and momentarily closed the cut-out points to polarise the generator, and the battery promptly reversed it's polarity to what it was supposed to be, and when I turned the headlights on it reversed itself again!!! Has any else ever come upon such a phenomenon?
Geoff
Geoff
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Comments
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There is no regulator, just a cut-out. It is connected normally, from the ammeter.0
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This Phenomenom is caused by the inate carnality of inanimate objects0
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LOL0
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Okay,. mystery solved. As you say, most problems are caused by human mishandling. The generator had been connect to the same terminal as the battery wire at the ammeter, hence it did not show a charge at all. What must have happened, the generator had been positive ground, and had been merrily charging away that way until the battery flipped polarity. None of this showed up on the ammeter, which co-incidentally had also been connected for positive ground. Of course all circuits work fine either way, apart from the ignition which is slightly compromised by having negative spark at the ground terminal, but it will still work. I have connected the ammeter correctly so that it now shows the charge rate. The battery is being discharged fully, and then recharged negative to negative and positive to positive on the charger. When fully charged I will momentarily close the cut-out points to re-polarise the generator and then everything should be tickety-boo! A good subject for my next "Tech Topics" in the W.T.N.!
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Geoff,
Just be sure to not let any smoke out of the system!
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That only applies to Lucas electrical systems Dave.0
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I stand corrected. 0 -
Geoff, I recall from my long ago aircraft electrical systems schooling that this can indeed happen with a mis-connected charger on a depleted battery.0
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It has been my experience that discharged batteries can behave in three ways when connected to a typical
battery charger.
1) The usual thing: While you are attempting to start the car, the starter turns slower and slower, stops, and the solenoid starts clicking.
In this case, if you connect a charger right away, the meter will go almost to full-scale. After some time, the meter's reading will gradually decrease, finally reaching a low amount, usually by the next day. This indicates that the battery is now fully charged.
2) Someone inadvertently left the dome light on last night, and nothing works, not even the smallest light.
In this case if you connect a charger, the battery will act like a short circuit. You will see the meter go above
full-scale. After a few seconds, the breaker in the charger will disconnect, and the meter will go to zero. Then the breaker will connect, the meter will go back to the top. This will keep happening. This is not good for the charger.
What I do is to connect a bulb between one clamp of the charger and a post of the battery. The other clamp of the charger stays on the other post of the battery. A sealed beam or a brake light bulb is good for this. The bulb will light, brightly at first. The next day the bulb will not be lit. I then remove the bulb, and the battery charges normally. It is best to turn off the charger when removing the bulb. This is because a spark can cause the battery to explode.
3) A battery has sat for months in a car or in the garage. It won't light a bulb.
In this case if you connect a charger, you will usually see no motion of the needle.
What I do is to connect the charger, and come back the next day. If it is a good battery, it will be charging normally, or may already be fully charged.
* * *
Many good batteries have been thrown away because of (2) and (3) !
Per
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For over 15 years a client of my consulting firm was a principle supplier of rechargeable battery technology for the US military. In my role I was privilidged to be an intergral part of much of the R&D work our country was doing in this area. Battery polarity reversal is a phenomenon related to cell chemistry and this can result in the single or all cells in a battery reversing.
THIS POST IS TO INFORM ALL THAT A BATTERY WITH REVERSED POLARITY IS DANGEROUS TO ALL WHO ATTEMPT RECHARGE.
There are plenty of documented cases of battery explosions both with liquid and sealed cell batteries. The cost of a battery is minuscule compared to the injury or loss of lives.
You will NEVER forget the images of any battery charging area that suffers an explosion and subsequent fire.
Do as you feel is right for you, but realize one 4X6x6 sealed cell 12 volt battery has the potential to blow holes Ina cinder block wall. Unfortunately, I saw multiple instances.0 -
For over 15 years a client of my consulting firm was a principle supplier of rechargeable battery technology for the US military. In my role I was privilidged to be an intergral part of much of the R&D work our country was doing in this area. Battery polarity reversal is a phenomenon related to cell chemistry and this can result in the single or all cells in a battery reversing.
THIS POST IS TO INFORM ALL THAT A BATTERY WITH REVERSED POLARITY IS DANGEROUS TO ALL WHO ATTEMPT RECHARGE.
There are plenty of documented cases of battery explosions both with liquid and sealed cell batteries. The cost of a battery is minuscule compared to the injury or loss of lives.
You will NEVER forget the images of any battery charging area that suffers an explosion and subsequent fire.
Do as you feel is right for you, but realize one 4X6x6 sealed cell 12 volt battery has the potential to blow holes Ina cinder block wall. Unfortunately, I saw multiple instances.0 -
Thank you all for your comments. the ca'rs owner took the battery back to the supplier, who were going to discharge it slowly, then recharge ti with the correct polarity. the problem obviously came about because the ammeter was wired incorrectly, and not showing the charge, and the generator had positive earth polarity, hence that is what the battery finished up as. Ammeter is now correctly wire, and generator has to be polarised with negative ground and everything should be fine.
Geoff0 -
Ken,
What kind of battery is an 8D? About what charging rate was being applied to it?
It is very sad about the fire started by the battery exploding.
Per
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Ken,
My experience is with small chargers, having a full-scale reading of 8 amperes. Usually if a battery is freshly discharged, the meter reads about 6 amps. If the battery is quite new, the reading when it gets fully charged is 1 or 2 amps. If the battery is getting old, the reading when fully charged may be about 3 amps.
I habitually leave batteries charging overnight, since I prefer to have the battery fully charged when I install it, and this takes many hours at this slow charging rate.
One time I witnessed a battery explode. It was a 6 volt (group 1) battery being charged with this type of charger outdoors under the hood of a '42 Hudson. The battery had been charging many hours. The owner of the charger made the mistake removing a clamp without unplugging the charger first causing a spark. The top of the battery flew up and hit the bottom of the hood. Fortunately nobody was hurt! We had to spray a lot of water under the hood and on the front fenders of the car.
I am making the guess that a lot of hydrogen was being produced due to a fast charging rate of the 8D battery, and that the explosion was so violent that the plates of the battery shorted out and produced so much heat that a fire started. Perhaps a poor connection of the charger to the battery became very hot or caused a spark.
Hydrogen is extremely explosive, like gasoline fumes, so there can be other sources of a spark or flame that can make it burn. In one case I heard of, gasoline dripping from a '27 Packard in a garage that contained a hot water heater was ignited by the pilot light in the water heater. I suppose that even the spark in the clock in my '49 Hudson would be enough, if the fumes were strong enough.
Thank you for presenting this information. It would be good, as a precaution, to charge batteries out of doors whenever possible.
Per
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All's well that ends well. Battery was completely discharged, and then trickle charged with correct polarity for several days. Installed in car, engine fired right up, and generator charging correctly.
Geoff0 -
Just make sure you don't have a female battery. sometimes both terminals are negative.0
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