Desulphator and SLA Battery Trial

Discussion in 'General Electronics Chat' started by tracecom, Apr 29, 2010.

  1. tracecom

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    Apr 16, 2010
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    I drug out one the four Portalac PE12V17 batteries that I have. It is identified as a sealed lead acid battery. The voltage on this one measured 6.8v with no load after sitting idle for about three years.

    The battery charger that I have has four settings: 6v, 10a fast charge; 12v, 2a float charge, 12v, 10a fast charge, and 12v, 55a start. When I set it to anything other than 12v, 55a start and try to measure the no load voltage, the output is zero. (I assume that it has a sensor that is shutting it off if there is no load?) On the 12v, 55a start position, it measures about 15.5 v with no load.

    So, I set it to 12v, 2a float, connected it to the battery, and then measured the voltage; it was 11.5v. However the ammeter on the charger seemed to be at zero current.

    After a couple of hours, the voltage on the battery with the charger connected was up to 12.5v, and the no load battery voltage without the charger connected was a little over 10v.

    So, I attached the desulphator, and reattached the battery charger (still on 2a float.) The LED on the desulphator is lit and I can hear the desulphator buzzing.

    I'll check the voltage again in the morning.

    Here's hoping that the battery is salvageable!

    (Of course, I know it will take a while; but I am encouraged by what I have seen so far.) :)
     
  2. tracecom

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    I just noticed that thecharger's "Charge Complete" LED has come on. Maybe the sensing circuitry on the charger doesn't like the desulphator? :confused:
     
  3. SgtWookie

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    It sounds to me like the battery has a shorted cell.
     
  4. tracecom

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    You may be right, however, I did disconnect the desulphator and the "charge complete" went out; hooked the desulphator back and the "charge complete" lit again. Tried a different PE12V17 and got the same result. Of course, both batteries are the same age and could both have a shorted cell, I suppose.
     
    Last edited: Apr 29, 2010
  5. SgtWookie

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    Did you read what I said about how to connect a trickle charger to the circuit?
     
  6. tracecom

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    Yes, I read it, but I forgot. I'll go back and read it again now.

    If this is what you mean, I read it, but I'm not sure what to make of it.

    "It is possible to use a trickle charger with this desulphator, if you connect the negative lead of the charger to the junction of L1/L2/C4/C5, and the positive lead to the positive rail (the wire running across the top of the schematic)."

    Is the connection you describe above different from just connecting the charger and the desulphator to the battery terminals, and if so, what are the advantages? And by a trickle charger, do you mean something less than the 2a charger I have connected now?


    ETA: OK, I do see the electrical difference in connecting the negative side of the charger to the junction of L1/L2, but how will that help? I don't have a charger smaller than 2a, but I have a 300ma and a 500ma 12.6vct transformer and I can make a trickle charger, if you can refer me to a schematic.
     
    Last edited: Apr 29, 2010
  7. SgtWookie

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    Start by trying to connect your 2A charger like I said.

    The idea is that the junction between the inductors has minimal noise on it.
     
  8. tracecom

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    Done! The "charge complete" LED on the charger went out while I had the charger disconnected and came back on when I reconnected the negative to the junction of L1/L2.

    ETA: The negative connection is via a 22awg 15" clip lead.
     
  9. SgtWookie

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    That's OK.

    Did you check the electrolyte level? If the plates aren't covered, you're spinning your wheels.
     
  10. tracecom

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    I'll have to try to figure out how to open the battery, but that will have to wait until Friday after work. Thanks.
     
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