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  1. #16
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    Since the transformer output would be, say 16 volts AC for argument, the peak DC would be 1.414 times that, around 22.5 volts. But this is not a pure DC output, there is no smoothing capacitance to knock off the peaks.
    My bad, 25v was a bit of an over calculation.
    With a battery connected this will do the smoothing and any measured voltage will be related to the load and how close to fully charged the battery is, it will still attempt to reach the 22.5 which will not be good for a lead acid battery. I would hope the secondary on the transformer is somewhat less than 15-16v.

    Measurement of the DC voltage without load will be inaccurate as most volt meters are not designed for measuring pulsed DC particularly modern low impedance digital meters.

    For electrolysis changing the distance of the electrodes or solution strength will assist if no voltage or current controls are available on the power supply.

  2. #17
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    I'm following along, I have a old awesome charger for over 20 years, my son used it and blew it up somehow but didn't know anything.
    Looks simple enough but I haven't looked into it.
    Using Tapatalk

  3. #18
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    Hi Dave, Guys,

    The usual cause of damage to those old style chargers is shorting out the terminals or reversing the polarity. The rectifiers don't like it and tend to stink the place out before going open circuit.

    But if the transformer is OK, the wax runs out when they get hot, a new bridge rectifier and a couple of diodes in series with the output should get you up and running again.
    Best Regards:
    Baron J.

  4. #19
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    Quote Originally Posted by BaronJ View Post
    Hi Guys,

    Since the transformer output would be, say 16 volts AC for argument, the peak DC would be 1.414 times that, around 22.5 volts. But this is not a pure DC output, there is no smoothing capacitance to knock off the peaks.

    At 6v setting it is only half wave rectified, so the 16 volts AC would become roughly half that times 1.414 at the rectifier output, about 14 volts, much nearer to the voltage required to charge a 12 volt lead acid battery rather than a 6 volt one.

    Also it should be possible to use a light dimmer to adjust the voltage input to the transformer to reduce the transformer output voltage, turning the charger into a crude variable voltage supply more suitable for electrolysis.

    JMTPW.
    Hi Guys.. appreciate the input...will check voltages at various places at get back to you all.
    Ken.

  5. #20
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    Hi guys.. Even though the switch tested OK for continuity, It appears that this may have been the fault after all... will replace the switch and see what happens after that.
    Ken

  6. #21
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    Quote Originally Posted by kenny_10 View Post
    Hi guys.. Even though the switch tested OK for continuity, It appears that this may have been the fault after all... will replace the switch and see what happens after that.
    Ken
    Hi Kenny,

    It might pay you to check that the transformer centre tap is not open circuit. The most effective way to do this is to use a 12 volt car side light bulb. A multimeter can sometimes tell you lies !
    Best Regards:
    Baron J.

  7. #22
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    Quote Originally Posted by BaronJ View Post
    Hi Kenny,

    It might pay you to check that the transformer centre tap is not open circuit. The most effective way to do this is to use a 12 volt car side light bulb. A multimeter can sometimes tell you lies !
    If it was the centre tap O/C then you would have 12v but no 6v. I believe the OP has the opposite.
    Not saying not to check the transformer.

  8. #23
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    A thought just occurred to me:

    @ Kenny_10, when you say you have 6v but not 12v is that the voltage you measured on the output leads or are you saying that when the unit is switched to 6v you have output and if switched to 12v there is none ?

    Without something connected to smooth the pulsed DC any measurement with a multimeter is going to be inaccurate.

  9. #24
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    Hi Guys,

    That is the reason that I suggested using a side light bulb to test with ! A bulb will easily show up the difference between 6 and 12 volts and show any high resistance or open circuits.

    For instance if the switch is just Hi Z in one position a multimeter could lie and tell you that there is a circuit there.

    This is a known problem with high impedance meters when measuring voltages. This problem was known way back in the early 1900's and was the reason that the "AVO" with its known 20K ohms per volt input impedance was always the specified reference when measuring voltages. So much so that "AVO" manufactured the model "7" with a 2000 ohms per volt specification, this multimeter was intended for use on circuits like this battery charger and other low voltage high current equipment.
    Best Regards:
    Baron J.

  10. #25
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    Quote Originally Posted by BaronJ View Post
    Hi Guys,

    That is the reason that I suggested using a side light bulb to test with ! A bulb will easily show up the difference between 6 and 12 volts and show any high resistance or open circuits.

    For instance if the switch is just Hi Z in one position a multimeter could lie and tell you that there is a circuit there.

    This is a known problem with high impedance meters when measuring voltages. This problem was known way back in the early 1900's and was the reason that the "AVO" with its known 20K ohms per volt input impedance was always the specified reference when measuring voltages. So much so that "AVO" manufactured the model "7" with a 2000 ohms per volt specification, this multimeter was intended for use on circuits like this battery charger and other low voltage high current equipment.
    May not even be high resistance, I wonder if his high impedance meter is reading 6v DC while it is connected to 12v pulsed DC there is absolutely nothing to store the charge. Sounds like a bit of a low reading if that is the case but worth the confirmation of what is being checked.

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