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Quick solar question

Discussion in 'General Electronics Discussion' started by natejp, Jun 5, 2010.

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  1. natejp

    natejp

    7
    0
    Apr 2, 2010
    I have a Solarlink FR360

    (http://www.rei.com/product/791889?p...-B299-DE11-93DB-0019B9C043EB&mr:referralID=NA)

    It apparently takes 10hrs!!! to charge a 3.6v 600mAh battery using the built in solar panel, but it has a 5v dc jack in the back. Can I just get a beefy 5v 250mA solar panel (like the one below), swap the alligator clips for a dc plug, and use it as is to supplement he built in panel? I assume overcharge protection for the battery and a diode are built into the solar link.

    http://cgi.ebay.com/1pc-1-25W-5V-25...ultDomain_0&hash=item3cadb23ccf#ht_4153wt_848

    Thanks,

    Nate
     
  2. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    Yes, I'd believe it would work, but of course one never knows how well the electronics is designed without having "reverse-engineered" it. Notice the 6V open-circuit voltage.
    Do you know if it has Ni-Mh or lithium batteries? There is already a diode in that panel, but I'd expect a DC jack to be reverse-current protected.
     
  3. natejp

    natejp

    7
    0
    Apr 2, 2010
    thanks for the reply!

    The battery is a 2/3AA NiMH 3.6v 600mA. What exactly is the open circuit voltage, why is it higher than 5v, and what implications does that have?

    Thanks,

    Nate
     
  4. davenn

    davenn Moderator

    13,555
    1,853
    Sep 5, 2009
    The open circuit voltage is the voltage you will measure across the output from the solar panel with no load present. Putting a load across the output will drop this voltage, but you have to be aware of if that drop is down to within the operating voltage of the equip you are running off the panel. This is where it sometimes becomes necessary to have an appropriate regulator circuit between the panel and the equip being powered.

    just for an example you mite have a bit of gear that requires 12VDC, the panel's open cct voltage is 20VDC, its load voltage is 16VDC, so it would have to be regulated down to the required 12VDC you need to avoid damaging your gear.

    Another thing to be aware of is the varying output voltage of the panel in response to the amount of sunlight illuminating it

    just a few thoughts :)

    Dave
     
    Last edited: Jun 6, 2010
  5. natejp

    natejp

    7
    0
    Apr 2, 2010
    Ok, so then is the ebayer saying that the load voltage of this panel is 5v? I figured that panel voltage was a constant entity and that only the amount of current varied proportionately to light intensity. This was based on the fact that panels are listed by the voltages they put out. Why is the open circuit voltage important? If it drops whenever a load is attached it seems kind of irrelevant.

    Thanks for your thoughts,

    Nate
     
  6. davenn

    davenn Moderator

    13,555
    1,853
    Sep 5, 2009
    Yes he is so for your application it should be all good and the open cct voltage of 6V shouldnt be a problem in your situation.

    I was referring to Solar Panels in general, an thinking about the much larger ones.
    reread my comments ad to why the open circuit voltage is an important factor (particularly
    on the higher ouotput panels) :)

    cheers
    Dave
     
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