28
September
2009

what happens if i connect a solar panel to a battery thats lower than the operating voltage?

If i connect a 9V solar panel to a 12V battery, will it be able to charge the battery up to 9V? Or will the current go the other way and not charge the battery at all?

You would typically have a blocking diode in place to prevent battery discharge (even cheep panels have this).

Your 9v panel is actually at 11.5v when there is no current. So you may be able to very slightly trickle charge a dead battery. I doubt you will be able to witness any results however.

The simple solution is to purchase a 12v panel :)

Another solution, if you do not wish to purchase a new panel, is to get a charge controller. A charge controller can boost the voltage to the proper charging values and protects the batteries when they are full.

Check them out at:
http://www.aurorapower.net/products/list/1/categoryid/13/level/a.aspx

Best of luck to you!

Posted under: solar panel

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4 comments

  1. Leciv:

    voltage sources with different voltages in paralell will probably cause a fire.
    References :

  2. veggie boy:

    I suspect it may "reverse bias" to solar panel so that it does not contribute any charge at all, unless the 12V battery is COMPLETELY dead. Even then, it would not give the battery a useful charge. Sorry; you need a 12V solar panel.
    References :

  3. Yaacov:

    The panel rating is supposed to be higher than the battery rating
    And yes it is possible but highly not recommended to connect the panel directly to the battery, it might open the door to the possibility of Over Current (too much current).
    It is absolutely recommended to have a Charge Controller to handle the current
    To get more insight you may view http://www.solar-energy-for-home.com/charge-controller.html
    References :

  4. ericnutsch:

    You would typically have a blocking diode in place to prevent battery discharge (even cheep panels have this).

    Your 9v panel is actually at 11.5v when there is no current. So you may be able to very slightly trickle charge a dead battery. I doubt you will be able to witness any results however.

    The simple solution is to purchase a 12v panel :)

    Another solution, if you do not wish to purchase a new panel, is to get a charge controller. A charge controller can boost the voltage to the proper charging values and protects the batteries when they are full.

    Check them out at:
    http://www.aurorapower.net/products/list/1/categoryid/13/level/a.aspx

    Best of luck to you!
    References :
    Im a Mechanical Engineer for an alternative energy company
    http://www.aurorapower.net/



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