24v to 12v amp conversion

Discussion in 'The Projects Forum' started by Prebstar, Apr 2, 2016.

  1. Prebstar

    Thread Starter New Member

    Apr 2, 2016
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    Hi,
    I will be using a MPPT solar charge regulator to charge my 12v 125amp AGM batteries.
    I have not got my solar panels yet, and came across some 180watt 24v panels at a good price, the MPPT controller is a 40 amp up to 60v, so that is ok.
    My question is what power output can I expect from the panels compared to a 180w 12v panel as far as charging my 12v Agm battery, thanks
     
  2. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,037
    1,663
    Hook them up and find out!
     
  3. #12

    Expert

    Nov 30, 2010
    16,298
    6,811
    Twelve volts will not charge a 12 volt battery because there is not enough voltage to drive current backwards through the battery. If 12V is the peak voltage of the 12V panel, you have a non-starter. Check the datasheets for each panel and see how they act when loaded down to about 13 volts.
     
  4. Prebstar

    Thread Starter New Member

    Apr 2, 2016
    2
    0
     
  5. #12

    Expert

    Nov 30, 2010
    16,298
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    Sure. That's what the manufacturers do when they characterize the panels. Unfortunately, I am not a manufacturer and I don't have your panels with me. In fact, I don't even know what brand or model number they are so I might go buy some and do the tests just for you. I'm afraid you will have to look them up or ask the manufacturer.
     
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,392
    1,605
    If your specs are correct you can expect exactly the same power out of either one: 180 watts.

    Practably the higher voltage panel may work a bit more efficiently than a lower voltage device as the switching losses thru the MPPT improve slightly with more voltage.

    One former member here built chargers professionally had mentioned MPPT was simply not worth it on 12 volt panels as there was no gain in efficiency.
     
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