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Help understanding solar panel and li-ion chargin

Discussion in 'General Electronics Discussion' started by xxopiumxx, Nov 24, 2017.

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  1. xxopiumxx

    xxopiumxx

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    Nov 10, 2017
    hi!

    Iam working in a project thats rellies in a 18650 battery, which is charged by a MCP73831 .
    Now I need to power the MCP charger with a solar panel, but I have came across the web several comments that claims that this IC is not suitable for solar panels.

    I quite dont understand why is that. It may be related on the variation of current from the solar panel, and therefore the IC cant determine in which charging state is should be?

    is there any workaround to this? some say to put specific buck boost converters designed to track the MPPT of tha panel (like the bq25504) . the problem is that I am from Argentina and that IC is not available .

    thanks in advance!
     
  2. Arouse1973

    Arouse1973 Adam

    5,164
    1,080
    Dec 18, 2013
    Why don't you have a support battery like a lead acid type to buffer the current from the solar panel. This will give you a steady supply of energy if the solar panel were to output less energy due to partial lack of the sun.
    Thanks
    Adam
     
  3. xxopiumxx

    xxopiumxx

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    Nov 10, 2017
    Thanks Arouse.
    I dont quite understand how would it be connected. And how could I keep this second battery charged.

    regards
     
  4. Arouse1973

    Arouse1973 Adam

    5,164
    1,080
    Dec 18, 2013
    The solar panel charges the backup battery and then you connect the battery to be charged to the backup battery using its charger. You will need a dedicated battery charger for the back-up battery i.e lead acid charger.
    Thanks
    Adam
     
  5. turbogt16v

    turbogt16v

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    Mar 27, 2015
    the solar panel need special charger, because thr current in not constant.you can get it on eBay for 2 or 3 dollars
     
  6. xxopiumxx

    xxopiumxx

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    Nov 10, 2017
    so, there is no way it could work with the mcp7383? even though the panel is rated way higher that the current consumption of the system?
     
  7. xxopiumxx

    xxopiumxx

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    Nov 10, 2017
    the problem is that to get one of those to argentina could take months.
    couldnt i put a dc-dc booster like the mt3608 fixed at 5V; and a big cap to help with current?
     
  8. turbogt16v

    turbogt16v

    173
    4
    Mar 27, 2015
    It would work only if ,your solar panels are rated 6v or less,and only when you have contant sunligh that will work with dc booster that is tuned from 3.7v to 6v, lower sun, charger dont work you will have to tunne it,to strong sun you will maybe fry the charger,so be carefull.
    So the best solution is to tune it when the sun is the strongest at 6v
     
    Last edited: Nov 27, 2017
  9. xxopiumxx

    xxopiumxx

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    0
    Nov 10, 2017
    sorry, now i fell that my theory is failing. If my charger requires, lets say, 250mA, but my panel is producing 500mA, were does that excess goes?
     
  10. turbogt16v

    turbogt16v

    173
    4
    Mar 27, 2015
    solar panels act as baterry them self,charrger will take how much it needs.so it will work
     
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