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Solar Charger Help Please

Discussion in 'General Electronics Discussion' started by Heeran, Jul 25, 2013.

  1. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    These are the images that I have of the MPPT circuit that we talking about.
     

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  2. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    A close up view
     

    Attached Files:

  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,118
    2,655
    Jan 21, 2010
    And I'm telling you that the circuit does not match the rest of the images.

    Note that the circuit has a PIC12 (8 pin device) and everything else has an 18 pin pic18.

    I can tell you that the images of the device are for more around 10A, but your schematic is for 1A or so.

    I realise you don't want to hear this, but it's true.
     
  4. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    hi, i do understand what you are saying, just running out of ways to buildmy own circuit. If we where to use the component layout schematic and upgrade it yo 15 amp, will that work or im i still hitting a dead end. Is there know way for me to achieve this outcum. Il change my budget, to what is required to try and get this circuit built.
     
  5. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    Hi
    I guess that schematic is not going to work seeing that you have not yet replied to me. Will you be able to help me build this circuit or is it not possible. Please let me know.
    Thanks
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    2,655
    Jan 21, 2010
    It's pointless building that circuit if you don't have the firmware for the PIC.
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,118
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    Jan 21, 2010
    If you had sufficient design skill and programming ability you could build one for yourself from first principles.

    For a basic MPPT system, all you need is a way to measure current and a buck regulator with a variable duty cycle.

    You start with a duty cycle (D) of (say) 10% and with a delta of +1%.

    You set the duty cycle to D + delta and measure the current. if it increases then you loop back to do it again. If it decreases, you set delta to -delta and loop back to try it again.

    That simple algorithm keeps the current at the maximum value.

    But wait, you might say, we want maximum power, not maximum current! This is true, but because we're charging a battery, we can consider the output voltage to be fixed, so power is proportional to current.

    That's the basics, but we probably also want to measure the battery voltage too so we can stop charging at some voltage (or perhaps to change from a maximum power mode to a lower current top-up mode) or to remove the load if the voltage falls below (say 10.5V).

    For a buck regulator from a solar panel, you are (surprisingly) not too concerned about saturating the inductor because the panel will limit the current and you're not actually losing energy.

    If you want more complexity you can measure the battery temperature and modify charging parameters accordingly.
     
  8. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    What you think of this circuit. Will it do what I need it to do.
     

    Attached Files:

    Last edited by a moderator: Aug 4, 2013
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,118
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    Jan 21, 2010
    It will probably work (post a link to the description, don't cut and paste it all).

    The efficiency will be lower (maybe 70% to 80%) of what you'd get with MPPT, but if that's OK, then go with it.
     
  10. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    Hi
    If you Google - ( Arduino PPT solar charger ) there is a circuit of a MPPT circuit, from the description it seem like a good circuit but it does not state to output current. Would you be able to tell me if this circuit could work and if so, does it require programing or just assemble and use.
    I also found another circuit that can be upgraded to a 20amp circuit output. The location of this circuit is www.solorb.com. I have attached a picture for this circuit so you would be able to identify it.
    Thanks
     

    Attached Files:

  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,118
    2,655
    Jan 21, 2010
    if you provide a link it is even better (that way we know we're talking about the same thing).

    Well, it shows it working with something like a 40W panel (I assume), so it is demonstrated at something less than 3.5A

    Well, he provides evidence that it does and I see no particular reason to doubt him.

    Of course it requires programming.

    He even has the source code on that page. It's trivial to program an arduino though, so don't let that put you off.

    I wish you could provide a link. Do I really have to go find it myself?
     
  12. Braswyn

    Braswyn

    1
    0
    Feb 20, 2019
  13. twister

    twister

    154
    5
    Feb 12, 2012
    http://Web results TL494 Pulse-Widt...ents PDFTexas Instruments › lit › gpn › tl494
    Hi. I used this chip and the circuit that is provided except I didn't use a coil or capacitor. It is hooked directly to the battery. It has worked good for about 10 years. It would sometimes change voltage till I changed the pot to a multiturn pot. I used a pot instead of the fixed resistors shown. One bad thing is that it will tear up a am radio due to the switching of the mosfets. I have changed the frequency from 1hz to kilahz. It doesn't affect tv or fm radio. I suggest that you just buy a regulator unless you just like to build stuff.
     

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  14. twister

    twister

    154
    5
    Feb 12, 2012
    I guess the link doesn't work for some reason. Just do a search for tl494.
     
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