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charging a 12V battery from a 48V dc source?

Discussion in 'General Electronics' started by jim w, Jan 9, 2005.

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  1. jim w

    jim w Guest

    I need to get 12V from a 48V Solar (PV) system. The 48V is charged by 4
    12Vdc PV panels, into eight 6V batteries.

    I have a need for 12Vdc. I could just use a power supply on the AC side
    of the inverter, but that seems like a waste of power
    (48Vdc->inverter->transformer->regulated_PS).


    Would it be reasonable to build a DC-DC drop-down switcher?
     
  2. Madhu

    Madhu Guest

    A DC-DC converter is the way to go. ETA-USA (http://www.eta-usa.com/)
    for one has a bunch of 48VDC input converter modules and using them is
    simplicity itself. Likewise you can do a search of 48VDC input DC-DC
    converters and come up with a lot of products that would match your
    needs. I would not use the inverter-transformer method.
    Madhu
     
  3. SteveB

    SteveB Guest

    I don't suppose you could just take +12v direct from the 2nd battery up the
    chain, a problem would be that the lower 2 batteries would get discharged
    quicker than the top 4, so rotation would be needed to even things out.
     
  4. ComTech

    ComTech Guest

    You're right a switcher would be the best way to go.

    But there is a cheap and dirty way of doing things. You could put a power
    resistor in series to your load. You would calculate the resistor by R = 36V
    / max current then calculate the wattage for the resistor. Again it is
    really dirty and you should use zener and capacitor, but then I would try
    the switcher.

    Best of luck to you,

    Comtech
     
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