UC3906 Battery Charger

Discussion in 'The Projects Forum' started by ShayanFiroozi, May 10, 2016.

  1. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
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  2. Lestraveled

    Well-Known Member

    May 19, 2014
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    You must have miss read the information. The transformer is described as a 30 VA, 1.25 amp, 18Volt transformer. 30 VA means 30 Volt Amps, or watts with a resistive load.
     
  3. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
    41
    1
    Wow,of course I missed it !! And what about battery ??? does this circuit detect amperage for my battery to provide proper amperage for charging it??
    Thank you
     
  4. Lestraveled

    Well-Known Member

    May 19, 2014
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    The UC3906, during bulk charge, outputs a constant current. It does not matter what size the battery is. The UC3906 does not sense the size or current of the battery, it simply outputs a fixed current (in bulk mode).
     
  5. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
    41
    1
    thank you Lestraveled

    but i think it's a 3 stage charger !! so it's not safe for a 12volts 2.2AH or 4.5AH battery ??
    how can i solve this problem ?
     
  6. Lestraveled

    Well-Known Member

    May 19, 2014
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    Why would it not be safe for a 2.2 or 4.5 AH battery??
     
  7. debe

    Well-Known Member

    Sep 21, 2010
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    I use one as a charger for 12V 4.5Ah battery & works fine.
     
  8. ShayanFiroozi

    Thread Starter Member

    Nov 18, 2015
    41
    1
    Because i'm gonna use a 3AMP transformer , so a 4.5AH battery should be charged at 450ma for better life time
     
  9. Lestraveled

    Well-Known Member

    May 19, 2014
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    It does not matter how big of a transformer you use, the UC3906 controls the current.
     
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