Help Wiring 2 solar panels with DC-DC Regulator and also Potentiometer help please.

Discussion in 'The Projects Forum' started by TlMLee, Oct 2, 2013.

  1. TlMLee

    Thread Starter New Member

    Oct 1, 2013
    3
    0
    Alright guys, so...I'm super new to all of this...other than basic circuits in physics. But, I'm trying to make a solar panel charger...that charges a 3200mAh batt and I'm wiring the two solar panels I'm using with a Mini DC-DC Voltage regulator.

    These are the parts of using:

    Mini DC-DC Voltage Stabilizer/Regulator Module
    http://www.ebay.com/itm/281150832404?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

    2X All-powers 2.5W 5V/500mA
    http://www.ebay.com/itm/15105570900...eName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

    Anker® Slim 3200mAh Portable Power Bank
    http://www.amazon.com/gp/product/B0054U6CEE/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

    So I'm using 2 solar panels so I can get a max of 5W(Is that even possible with the panels though?)

    I was thinking I could hook the positives of both panels to the + input of the regulator and hook the negatives of both panels to the -input of the regulator and a stripped microUSB(to charge the battery) to output side of the regulator. Then I plug my phone into the USB on the power bank. Would this work?

    Also...another question I have is with the pot on the regulator....its a small blue screw type one that i can turn. I had to turn it many times before I finally heard a click. Now with every full clockwise turn there's a click? Can anybody tell me how to measure it?(Does each click indicate a increase in voltage? Or does the click mean that it's returning to a minimum, and right before the click is a maximum?)

    My last question is: I originally was gonna have a USB hub connected to the USB port of the power bank and do my charging through that, but wouldn't that be much slower than straight from the power bank?

    I got my ideas and guidance from this guide before coming here :
    http://www.instructables.com/id/DIY-Portable-USB-Solar-Charger-20-4-Ports/

    Thank you very much if you take the time to answer.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,038
    Two panels in parallel should be OK but there is some risk that one panel will force current through the other, if they are not similar and seeing similar illumination. You might consider putting them is series instead. I think you're overall efficiency would increase.

    IMHO, the clicking indicates you are at the end of the range. I don't think it returns to the other end with a click.

    Yes, probably. But I think the device being charged expects the 5V USB source and is designed to regulate charging when supplied that way. So I'm not sure you can avoid that. Maybe you meant adjusting your regulator to 5V output? That would work if it actually holds the voltage steady.
     
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  3. TlMLee

    Thread Starter New Member

    Oct 1, 2013
    3
    0
    Thank you for your reply. In this situation how'd I go about in setting them up in series? (BTW they are the exact same solar panels.) And also could you elaborate on the last thing you said about the 5V USB source? Are you saying that no matter what the device will charge slowly?
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,038
    Series connection is using them just like using batteries in a flashlight; the positive of one panel connects to the negative of the other. Voltage doubles.

    The USB comment related to charging a device like a smartphone that expects to be plugged into a 5V USB port. This may not be your situation - please provide details of what you want to do.
     
  5. TlMLee

    Thread Starter New Member

    Oct 1, 2013
    3
    0
    Ohhhhh okay. I mostly plan to use this to charge cell phones, like my Galaxy S3. I plan to have the solar panels charge the power bank...then have the power bank charge the phone.
     
  6. cornishlad

    Member

    Jul 31, 2013
    196
    25
    I am not sure what advantage there is in series connection but the offload voltage of the panels may well reach the maximum allowable input voltage for that module (in bright sunlight)

    The panels would need to be mounted adjacent to avoid one getting into shadow while the other isn't. resulting in little output. Fine point I know but important with bigger units.

    Those pots are multi turn. when it clicks the internal "follower" is jumping the worm drive. The only way is back.
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,038
    The specs for his DC-DC converter show the minimum input voltage is 4V and the max current is 3A. In parallel and under load, his PV panels will be drawn below the 4V threshold much of the time. And in full sun, the current may well cook his converter.
     
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