LM3652 IC, solar based battery charger

Discussion in 'The Projects Forum' started by PersianEngineer, Jul 24, 2014.

  1. PersianEngineer

    Thread Starter New Member

    Aug 15, 2013
    19
    0
    I wanted to try LM3652 to charge a 6v SLA Battery. I calculated the values for resistors and inductor connected to the IC. I checked many times every thing but it's not charging the battery and instead it's drawing current from the battery. also the LED's that I have connected to pins CHRG and FAULT are ON. I'll try to post the schematic but for now, does any body have any experience or any idea why it's happening?
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,123
    3,048
    One thing that is universal is the easy mistake of getting the pinout wrong. Everyone does it from time to time. So a picture may also be helpful, in addition to the schematic. A second set of eyes is always helpful.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,986
    745
    have you built the circuit on the datasheet?
     
    Last edited: Jul 24, 2014
  4. wmodavis

    Well-Known Member

    Oct 23, 2010
    737
    150
    What is the voltage input to your circuit? What is the output voltage of your circuit? Are you using a diode to prevent battery discharge through your 'charging' circuit?

    More info including schematic & pictures needed to enable us to provide you with any significant help beyond just guessing. You must decide if you want guessing help or real help.
     
  5. PersianEngineer

    Thread Starter New Member

    Aug 15, 2013
    19
    0
    Thanks guys.
    This is the schematic:
    [​IMG]
    The battery is SLA 6v and I ve used the schematic in the first page of datasheet and calculated the value of resistors, now the threshold voltage of battery is more than 6v, 6.4 or 6.3 I guess and the current voltage of batter is 5.99 so it is supposed to be charged to 6.4v and then Vfb becomes 3.3v and the charging will be stopped. The calculated value of inductor for I guess 1mA fluctuation was 0.5 but because of unavailability I used 1uH and also the calculated value for Rsense was 0.5 ohm but I used the smaller one that I had.
    You can see the currents in the circuit in the schematic.

    This are the pictures of implementation on the breadboard:
    [​IMG]
    [​IMG]
    [​IMG]

    Any idea?
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    With a solar panel producing 25mA, you can just connect direct to the 6v SLA battery.

    Lead acid batteries won't overcharge when trickled with such a low current for 5 to 6 hours a day! :)
     
  7. PersianEngineer

    Thread Starter New Member

    Aug 15, 2013
    19
    0
    Actually 25mA current was just in a cloudy day other wise it goes to 100-200mA. I need to know what's wrong in this circuit or with IC?
     
  8. PersianEngineer

    Thread Starter New Member

    Aug 15, 2013
    19
    0
    One question, where is exactly pin 13 (SGND) which is mentioned in the page 8 of datasheet as following, Is that in the backside (bottom) of the IC that. I 've ignored it?
    SGND (Pin 13): Ground Reference and Backside ExposedLead Frame Thermal Connection. Solder the exposed lead frame to the PCB ground plane.
     
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