battery charge circuit

Discussion in 'The Projects Forum' started by david1234, Aug 20, 2014.

  1. david1234

    Thread Starter Member

    Nov 27, 2013
    81
    1
    I need to build a circuit that will charge the battery and also will make my system work.
    while charging - the system will work on 220AC (the power from the charger, and not the battery)
    and when I disconnect the charger - the system will continue working smoothly.
    for example - like we have in the cellular phone \ any PC

    how do I start?
    the battery is LiPo Vnominal=11.1V 2000mAh Max charge 12.8V

    Thanks ,
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,980
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    Here is a Lipo charger for different cells and capacities, what is the battery powering?
     
  3. david1234

    Thread Starter Member

    Nov 27, 2013
    81
    1
    what do you mean ?
    the use of it?
    something like a DVR
     
  4. Lyncheese

    New Member

    Jun 28, 2014
    22
    0
    Hmmm... nice project. I'm looking forward to it. I'm curious too....
    Btw, maybe there are already some module which also has that feature....

    You could just get the schematic from their web or reverse engineering it by yourself.
    I think It's not a bad way to start..

    Anyway, Good Luck..
     
  5. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,287
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    Bad idea... Deleted.
     
    Last edited: Aug 20, 2014
  6. ronv

    AAC Fanatic!

    Nov 12, 2008
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  7. david1234

    Thread Starter Member

    Nov 27, 2013
    81
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    Last edited: Aug 21, 2014
  8. ronv

    AAC Fanatic!

    Nov 12, 2008
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  9. david1234

    Thread Starter Member

    Nov 27, 2013
    81
    1
    just to see I understand
    if I take -
    Figure 1. Automatic Switchover of Load Between a Battery and a Wall Adapter

    then :
    Battery cell - I connect the battery
    To-Load - connect to my device (DVR)
    Wall adapter input - to my 220AC-12DC charger \or any other external battery
    PIN4(stat) - I can put a simple LED the will let me know when the battery is charging ?

    Thanks ,



     
  10. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Here is how I would do your thing....

    I wouldn't use a LiPo. I would use a Sealed Lead Acid battery.

    First, you need a well-regulated AC powered DC supply that can be set to the ideal float voltage (13.65V @ 25deg C) for Sealed Lead Acid batteries.

    If you have that, you can simply parallel the supply, the battery and the load.

    To tell if the system is running on AC or battery, either just use an AC indicator, or use the voltage detector circuit pictured. If the AC fails, and the system is being kept alive by the battery, the voltage will instantly drop from the float voltage (13.65V) to less than 13V (the intrinsic battery voltage). As the battery discharges, the voltage will drop slowly towards ~11.5V, which is a good ending point where the load needs to be disconnected.
     
  11. david1234

    Thread Starter Member

    Nov 27, 2013
    81
    1
    I have only LiPo battery.this is what I have , can't change it
    so what can I do?
     
  12. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    LiPo is a very complex system. It is not suitable for floating in parallel with a continuous load.

    It will take a commercial charger to charge the battery in isolation while a separate DC supply is connected to the load. The switch-over from AC to battery will happen when the AC drops. You need a low-voltage disconnect circuit to protect the LiPo if the AC stays off too long...
     
  13. ronv

    AAC Fanatic!

    Nov 12, 2008
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    You also need a lipo charger, like fig. 3 in the data sheet.
     
  14. david1234

    Thread Starter Member

    Nov 27, 2013
    81
    1
    I have search some more
    and found this circuit\device
    http://www.linear.com/product/LT3652

    I will just have to change the RC part to make it work
    for me (charge of 1A\12V)
    what do you think?
     
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