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I need help on building some DIY solar projects (portable)

Shaye2 | Posted in General Questions on

I have done a lot of research and visited many sites but still cannot figure out a few things with a portable solar charging project that I’m working on… I need help with figuring out a solar design to charge say my phone. Is it possible to hookup a wall charger to the output part and it wiil do all the work? Also I’m including batteries and Need to know how to set it up so that the phone will be powered by the panels and battery and the charge will be there only when I plug in the phone… No wasted energy.
So here’s all of my knowledge from research:
I know that solar is different from plugs because when solar cells absorb sunlight they immediately turn sunlight into Direct Current (DC) electricity and an inverter can then change it into Alternating Current (AC) which is what appliances that plug into your house use, but phones and things like that run off of DC.
I know:
-The workings of volts amps and watts.
-Wall chargers invert AC to DC and control energy output.
-My phone charges on no more than 12 volts and 1 amp
-A Voltage regulator could be needed so the battery does not get overloaded with energy
-I need a diode to put on the part that goes to the USB port so the energy doesn’t go back
-The diode could be void if wiring in the wall charger would work. I still don’t know if it will work like that
-Also it was said that a switch could keep the battery charging and not sharing electricity with an idle port

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  1. GBA Editor
    Martin Holladay | | #1

    You're on the right track. The easiest thing to do, however, is to buy a small PV module designed to charge cell phones. These gadgets cost $20 to $50. I don't think you can buy the parts and solder them together for any cheaper. There are lots of models available online.

    It's been a long time -- probably since the 1960s -- since a hobbyist could solder electronic parts together and save any money.

    In the old days, Radio Shack sold diodes and capacitors, jacks and plugs, and small empty plastic boxes for hobbyists. Then they sold cheap toys from China. Now they are about to file for bankruptcy.

  2. Shaye2 | | #2

    Thank you for the reply. I found people at "solar panel talk" to be rather rude and they also, to not get into detail, said that if i asked one more question about a DIY i would be banned even though i only asked once and was talking just as i am now... So i left and this is actuall a much better site. Again thank you for the answer.
    Also just to clear something even if i took the plugs off of the wall USB charger and connected it to the output it would not work properly? And I would have to buy a PV module indstead?

  3. GBA Editor
    Martin Holladay | | #3

    If you choose a PV module that has an output that matches the voltage and amperage of a "wall cube" charger designed for your cell phone, the PV module should charge your cell phone just fine. DC electricity is pretty simple. Two wires come off the PV module; connect these to the jack that fits your phone, and you are good to go. (Of course, you need to respect polarity -- which means that the positive lead from the PV module has to be connected to the right wire.) As far as I know, cell phones have some ability to accept a range of voltages and amperages.

    The wall cube has three components: (a) The plugs designed to fit an AC receptacle; (b) the cube itself, which converts 120 volts AC to 6 volts DC (or 9 volts DC or 12 volts DC); and (c) the output plug that fits the tiny jack on your cell phone. If you want to use a solar module to charge your phone, you can throw away the wall cube and just save the output wires and the tiny plug.

    The main concern is to prevent overcharging. I don't know what kinds of circuitry cell phones have to prevent overcharging. The main problem with solar chargers for cell phones is not overcharging -- it's remembering to plug the PV panel into the phone when the sun is shining, and having enough sun when you need it. One simple way to prevent overcharging is to keep an eye on the set-up and to unplug the panel when the phone is charged. But perhaps another GBA reader has some advice on this topic.

  4. Shaye2 | | #4

    Thank you yet again and I've already taken another approach per your advice. I have another thread question and was wondering if you knew anything about it? It is in general questions and is about an amp to voltage conversion ratio. Thank you again.

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