12VDC Battery Question

Discussion in 'General Electronics Chat' started by mpcotuong, Mar 6, 2012.

  1. mpcotuong

    Thread Starter Member

    Aug 26, 2010
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    0
    Hi All,

    I am using 12VDC battery for my circuit. How do I know when I need to recharge the battery? Do you have any circuit to tell that the battery need to recharge by display LED?

    Thanks,
    Kevin
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    What type of battery?
     
  3. mpcotuong

    Thread Starter Member

    Aug 26, 2010
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    It's 12VDC Lead Acid Battery.

    Thanks,
    Kevin
     
  4. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    Then you just use a comparator set to trip at about 12V (12.6V is full charge). That will indicate a discharge of the battery to about the 50% point. Going lower than that will tend to shorten the life of the battery.
     
  5. mpcotuong

    Thread Starter Member

    Aug 26, 2010
    170
    0
    What is the voltage need to recharge? can you more specific? Anh if you have the circuit is great.

    Thanks,
    Kevin
     
  6. Vahe

    Member

    Mar 3, 2011
    75
    9
    If this is an automotive lead acid battery, then you may be able to use the technique that is used there. The alternator voltage is regulated at about 14.2V or so that the terminal voltage at the battery is about 13.5V. This is to account for the voltage drops along cables. So I think if you can have the terminal voltage at about 13.5V, you can push current into the battery to charge it. The open-circuit voltage of the automotive lead-acid battery is about 12.6-12.8V (2.1-2.15V per lead acid cell, 6 cells per battery pack).
     
  7. mpcotuong

    Thread Starter Member

    Aug 26, 2010
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    Thanks, Vahe for explain but I need circuit to tell once need recharge the battery?

    Kevin
     
  8. stanman11

    Member

    Nov 23, 2010
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  9. mpcotuong

    Thread Starter Member

    Aug 26, 2010
    170
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    Thanks, Stanman11. It help. I will try it.

    Kevin
     
  10. stanman11

    Member

    Nov 23, 2010
    230
    4
    your welcome kevin
     
  11. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
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    Kevin, I think you have a low battery warning ckt mixed in with weight dpop ckt. composed of a LM 393 comp, V divider, precision ref Lm 385Z- 1.233 V, & red LED.
     
  12. mpcotuong

    Thread Starter Member

    Aug 26, 2010
    170
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    Thanks, Bernard. You mean the reference circuit you sent to me last time?

    Kevin
     
  13. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Before that- think it may be in picture file
     
  14. mpcotuong

    Thread Starter Member

    Aug 26, 2010
    170
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    Thanks, Bernard so much.

    Kevin.
     
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