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Thread: An Electrical "First", for Me!

  1. #1 An Electrical "First", for Me! 
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    Wife's T-V remote displayed "Battery Low" for a week, finally quit today. I often check cells of our gizmos containing more than one cell, for the heck of it. The remote uses 4 AAA cells. I found 1.2V, 1.3V, 1.0V, and, read it CAREFULLY: - 0.6V!! (??). I double-checked my leads, Simpson 260 meter, and sure enough, this cell had REVERSED it's polarity! It is an alkaline, Energizer brand.

    I have never seen this in all my years of electrical work and experience! Have any of you seen it, or offer an explanation? I am sadly out-dated with my DeVry Technical Institute Degree of many years ago, but do understand the chemical-electrical workings of the old original "dry cells".

    Thanks for reading! jocular


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  3. #2  
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    I've never seen it- but I have low knowledge. More handy-man around the house type when it comes to electrical.

    Googling structure of the battery, though, I cannot see how that would happen...


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    I never thought about it before, but I think I see how that could happen. You had one dead battery in series with 3 good batteries. Since they are wired in series, they all carry the same current. When the dead battery goes totally dead, it is still having current forced through it in the forward direction. This is like charging in reverse. A charger forces current in the opposite direction of the battery's polarity, so forcing current in the forward direction is reverse charging.

    ETA: found this. https://en.wikipedia.org/wiki/Rechargeable_battery
    Subjecting a discharged cell to a current in the direction which tends to discharge it further, rather than charge it, is called reverse charging. Generally, pushing current through a discharged cell in this way causes undesirable and irreversible chemical reactions to occur, resulting in permanent damage to the cell. Reverse charging can occur under a number of circumstances, the two most common being:
    • When a battery or cell is connected to a charging circuit the wrong way around.
    • When a battery made of several cells connected in series is deeply discharged.
    Last edited by Harold14370; June 20th, 2013 at 03:54 AM.
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  5. #4  
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    Quote Originally Posted by Harold14370 View Post
    I never thought about it before, but I think I see how that could happen. You had one dead battery in series with 3 good batteries. Since they are wired in series, they all carry the same current. When the dead battery goes totally dead, it is still having current forced through it in the forward direction. This is like charging in reverse. A charger forces current in the opposite direction of the battery's polarity, so forcing current in the forward direction is reverse charging.

    ETA: found this. https://en.wikipedia.org/wiki/Rechargeable_battery
    Subjecting a discharged cell to a current in the direction which tends to discharge it further, rather than charge it, is called reverse charging. Generally, pushing current through a discharged cell in this way causes undesirable and irreversible chemical reactions to occur, resulting in permanent damage to the cell. Reverse charging can occur under a number of circumstances, the two most common being:
    • When a battery or cell is connected to a charging circuit the wrong way around.
    • When a battery made of several cells connected in series is deeply discharged.
    I thought about what you're saying, but did not mention it, as I always believed the electrochemical process producing an EMF always must produce it with the same polarity, which, if so, precludes reverse-current charging beyond the zero-point. As you say, I've never seen this occur before, and my curiosity was pushed beyond the limitation which says "just drop it"! jocular
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    I hear what you're saying. I'm not too sure about the chemical reaction that would make the reverse polarity. Maybe a chemist will weigh in, or I'll look at it when I have more time.
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