Help fixing a car battery charger.

Discussion in 'Technical Repair' started by Mr Babu Mistry, Jun 12, 2018.

  1. Mr Babu Mistry

    Thread Starter New Member

    May 8, 2018
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    Hi i am looking for a diagram on a battery charger with diodes, as I have very old battery charger without diodes.
    If anyone can give the drawing on how to replace Diodes with diode velue.
    Thanks
    Lofty
     
  2. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    However old it is it must have at least one diode!
    How much current is the charger rated at?
     
  3. bertus

    Administrator

    Apr 5, 2008
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    shortbus likes this.
  4. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Simplest one uses a bridge rectifier and transformer ...


    battery charger charger for car battery and motorcycle battery.JPG
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    Does the battery charger have something that looks like this?


    upload_2018-6-12_14-3-8.jpeg

    This is a photo of a selenium rectifier (diode).
     
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  6. Mr Babu Mistry

    Thread Starter New Member

    May 8, 2018
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    Hi This is a English DAVEN set 6/12 volts, It is so simple it does not have selenium rectifier.
    Let me give you the photo how it is inside and outside.

    images.jpg

    IMG_20180613_111036.jpg

    IMG_20180613_111148.jpg


     
    Last edited by a moderator: Jun 13, 2018
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    There's only one wire going to the thermal cut-out at top right of the picture, so what you show can't be the complete charger.
     
  8. ericgibbs

    Moderator

    Jan 29, 2010
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    hi,
    Check this image.
    E
    ESP1 13-Jun-18 10.03.gif
     
  9. Mr Babu Mistry

    Thread Starter New Member

    May 8, 2018
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    Yes it is just like you see let me exemple how this Charger works, there are two out put one is 6 volts and the other is 12 volts the main wire goes through fuse and the other wire goes from thermal to two way switch to select charging current 6/12 volt that it.
    It is working just fine but I need to put Diode can i do that.
     
  10. crutschow

    Expert

    Mar 14, 2008
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    If it worked previously without a diode than why does it need one now? :confused:
     
  11. Mr Babu Mistry

    Thread Starter New Member

    May 8, 2018
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    Just thought to put diode so if someone puts the positive on wrong side it should help the fuse or thermal cut-out.
     
  12. crutschow

    Expert

    Mar 14, 2008
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    A diode won't help that.
    Think about it.
    The normal charging current it out of the charger and into the positive battery terminal.
    If the battery is reversed, the current will still be in the same direction, only much larger, so the only protection for that is a fuse or circuit breaker.
     
  13. ericgibbs

    Moderator

    Jan 29, 2010
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    hi,
    Looking at the TS's photo's, there seems to be a regular cartridge fuse.
    In series with the secondary winding, is what looks like a thermal cut out, could that actually be very a old fashioned mechanical vibrating rectifier that is magnetically energised by its proximity to the transformer magnetic field.????
    E
     
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  14. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    Good thought. It may well be.
    Does it vibrate when the transformer is connected to the mains? That would clinch it.
     
  15. crutschow

    Expert

    Mar 14, 2008
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    The magnetic field would pull the contact at twice the line frequency, so I don't see how that could work as a mechanical rectifier. :confused:
     
  16. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    Unless the blade is magnetised or has a magnet attached to the back.
     
  17. ericgibbs

    Moderator

    Jan 29, 2010
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    hi Babu,
    Could you confirm that when you last had it charging a battery, it had no rectifier of any kind.??

    E
     
  18. Mr Babu Mistry

    Thread Starter New Member

    May 8, 2018
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    Yes and it is working very okay.
     
  19. Mr Babu Mistry

    Thread Starter New Member

    May 8, 2018
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    yes there are no rectifier
     
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