Lithium Ion charger circuit question

Discussion in 'The Projects Forum' started by bisctboy, May 21, 2009.

  1. bisctboy

    Thread Starter Member

    Nov 3, 2008
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    If I am charging a 3.7v lithium ion battery through a solar panel that puts out 4.3v and 140ma, do I need a special charging circuit? Most specs on commercial lithium ion chargers indicate that the output from my solar panel is around their outputs.

    Thanks,
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
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  3. bisctboy

    Thread Starter Member

    Nov 3, 2008
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    Thank you....
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
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    After reading " Charging lithium-ion batteries", you'll need more inf,. on the solar panel."puts out 4.3V and 140 mA" Guessing again they mean open ckt. V & short ckt.I. At max output power S.P. V would be around 3V, charging at almost OC V, might charge @ 5mA.Battery management now needs to have boost capability. Also helpfull would be battery capacity in mA hrs. I'm throwing in the solar panel graph for kicks. Current about the same as your panel, dividing V by 4.2 will be close to the C.P. OC V.
     
  5. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Measure the voltage of the cell while being charged to not exceed 4.1V and you will be fine.
     
  6. thingmaker3

    Retired Moderator

    May 16, 2005
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    A charge controller will do this automatically, without ever becoming distracted. Better to err on the side of caution. Fire is a nifty servant but a terrible master.
     
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