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Basic Electrical Work

Discussion in 'General Electronics Discussion' started by SkullSpike, Oct 27, 2012.

  1. SkullSpike

    SkullSpike

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    Oct 27, 2012
    This is my first electrical project. I built a USB Portable charger/power output device. My question is rather simple. I'm using a Solar Panel and a Re-chargeable Battery; I simply need to know if the Solar Panel can charge the battery at all, or if it is more or less a wasted effort.

    Solar Panel:
    Typical Power Output: 1W
    Typical Output Voltage: 9V ~5%
    Typical Output Current: 112mA ~5%

    Re-chargeable Battery:
    Typical Power Output: 9V DC
    Typical Current: 170mA

    Please note that the circuit of the battery can be turned off for charging cycle(s). Creating a direct link between the battery and solar panel; with the positive lead of the solar panel using a diode for 1-Way energy transfer.
     
    Last edited by a moderator: Oct 27, 2012
  2. donkey

    donkey

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    Feb 26, 2011
    it is possible... but you would want it to charge slightly above the battery's rating. and to avoid backflow you would need a diode which could drop the charge by about 1volt.

    2 things you should put in diode and slightly higher voltage then actually needed
     
  3. SkullSpike

    SkullSpike

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    Oct 27, 2012
    This is the design I currently have, in the best way I knew to attempt to explain it. I drew the ground Diode backwards...

    It was the best way I knew to design it; was just attempting to make something and have fun, :) I may be killing the battery with that LED loop as well, not quite sure.

    Since I am using a 9V Solar Panel and a 9V re-chargeable battery... Is it even possible to overload the battery using solar?
     

    Attached Files:

    Last edited: Oct 27, 2012
  4. donkey

    donkey

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    Feb 26, 2011
    put a switch in there. it will stop the battery being on when its not needed.
    now comes the fun part. Ideally you want to discharge the battery bout once a month. get it as low as you can and then do a full recharge.
    on another note have you tried hand dynamos? I see alot of people using solar, but on cloudy days they're not the best. a hand dynamo with rectifier might be good too.

    as for overloading, will yes and no. what usually happens is when the battery has more power than the solar the battery starts powering the solar panels (it doesn't appear to do anything really) which can wreck your panels. that is what the diode is used for to stop the battery getting more power than the panels and back flowing.
     
  5. SkullSpike

    SkullSpike

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    0
    Oct 27, 2012
    I put a SPDT Slider Switch for the LED loop, it helped a lot. No more unnecessary draw on the battery. A diode to stop back-flow. I suppose I could look into hand dynamos, but the main purpose was hands free (I actually made it to use my Headset as head-phones, and to charge my Zune on long trips, plus it was fun as anything; 4+ hours passed while I was designing and building, thought it was only one, :D)

    Thanks for your suggestions!
     
  6. SkullSpike

    SkullSpike

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    Oct 27, 2012
    Project Done

    I thought I would upload some photos of the finished project!
    It doesn't look perfect, but it works!

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  7. donkey

    donkey

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    Feb 26, 2011
    nice. just one question, why did you not use a dpdt?
    you want to turn of the led and circuit at once, the LED will be an indicator showing the circuit is active and the battery has some charge so having it on at the same time as the regulator might be a good idea.
     
  8. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    What's the purpose of the Diode connected to the GND terminal of the 5V regulator? If you're intent is to get 5.7V from the output pin of the regulator you have it wired wrong.
    The polarity of the Diode is backward and your USB negative (GND) pin is not connected to circuit ground.

    I assume the Zener is used to keep the LED off until the battery voltage has charged high enough to overcome its threshold voltage. Also, what's the purpose of the Diode connected to the second switch that's connected to the input pin of the regulator?

    Chris
     
  9. donkey

    donkey

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    Feb 26, 2011
    cd drive I think he realised that a few posts back.

    The big thing is that you have 3 diodes. now having one from solar cell to battery is ok, but the rest of the circuit is DC so you shouldn't need the others.
     
  10. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    That's my point. I don't see the purpose for either diode connected to the regulator. The gnd pin diode, when properly wired, will raise the reg output +0.7V but why? This still doesn't explain the other one on the reg input pin.

    Also, as sop I always employ input and output caps, as per data sheet recommendations.

    Chris
     
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