Battery Charger/ Desulfator Problem

Discussion in 'The Projects Forum' started by caperren, Apr 30, 2011.

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  1. caperren

    Thread Starter New Member

    Apr 30, 2011
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    I will start this by letting you know that I have almost no experience working with AC projects except for enough to know that I needed to take extra safety precautions when working with it. I have a bunch of sulfated lead acid batteries that I wanted to bring back to a usable state. I eventually found a very simple DIY desulfation circuit that would require one to check back on the battery to make sure it didn't get too hot and did not overcharge. I was fine with this and decided to build one. Here is the link to the project I modified....

    <SNIP>

    It is a fairly simple circuit and so I ordered a few run capacitors, a 600v 50amp bridge rectifier, some switches, and some extra random parts from eBay. One of the capacitors is a dual run one, which I have never used before. Please refer to my attached circuit diagram for the rest of this post and please note that I have separated the dual post capacitor into two 24mfd independent capacitors as I could not find a dual post one in TinyCAD. I redesigned the circuit from above to allow for me to individually select which capacitors were connected at any given time so I could change charging rates. I also removed the volt and amp meter leads and switch as I will be changing the project later to a more sophisticated design that will monitor those using it's own circuits. I think my mistake was trying to use both parts of the dual post capacitor on the same circuit. After turning it on, the lights in my garage dimmed, the output to the battery was 170volts (which I expected), and I was drawing somewhere between ten and twenty amps (my 20amp circuit breaker did not trip and my 10 amp ammeter peaked). With only one post of the capacitor selected, the voltage and amps would drop to normal levels within seconds of turning it on, about a 1 amp charging rate (I don't remember how many volts). Before and while it was dropping, it sounded similar to a transformer, though louder than any I have ever heard. When the amps dropped, that went away. So, I figured that it was working and then saw smoke coming from my project box. I unplugged it, drained the capacitors, and opened the box up outside. It seemed to me that the "smoke" was more like vaporized electrolytic fluid. Also, everything in the box was covered in a layer of some liquid and the dual post capacitor was bulging (the 160mfd was not). Was the problem with this circuit that I used a dual post capacitor (there is a common ground for both sections on this particular capacitor), or is there something else in my circuit I am missing? Also, if there is something wrong with my schematic, let me know as I have never used a program to make on before. Any help, thoughts, suggestion would be appreciated.

    Well, after writing this, I just realized that I'm not sure whether that specific capacitor was rated for anywhere near 170volts and then that would make total sense as to why it is bulging and vaporizing. I will check tomorrow. Still, if anyone has anything that might help make my project better, safer, etc... or if they think something else might have caused it, let me know....
     
    Last edited by a moderator: May 1, 2011
  2. caperren

    Thread Starter New Member

    Apr 30, 2011
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    I just checked and it turns out that that capacitor was rated for 400volts, so it should have been fine. This would lead me to believe that it is a problem with it being dual post. Anyway, thanks for any help you can give...
     
  3. Adjuster

    Well-Known Member

    Dec 26, 2010
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    This sounds horribly dangerous. My guess would be that at least one of the capacitors you were using was an electrolytic type not designed for AC use. This forum does not encourage circuits running directly off the mains, and frankly the experience you have had illustrates the dangers of this sort of thing.

    Personally I would have nothing to do with a battery charger that does not include an isolating transformer.
     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Any capacitor used in series or parallel with AC mains should be rated as a suppression capacitor, these are designed to handle the signal they get. Regardless if you put too many amps through any capacitor in series it's not going to like it.
     
  5. bertus

    Administrator

    Apr 5, 2008
    15,652
    2,348
    Hello,

    The circuit is VERY dangerous as it is directly mains powered.
    I have removed the circuit diagrams, as we do not want people to get hurt or even killed.

    Bertus
     
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