Foldapan is for outdoor enthusiasts who want to charge their electronic gadgets on the move.
The folding panel is powerful enough to run a small mp3 player-speaker under direct sunlight.
It can also charge phones and other instrument which can be charged thry usb port.
project is done by using 4 solar panels, 2 usb sockets, a 7805 regulator and 4 1N5819 schottky diods.
each panel is able to generate around 8.5V open circuit voltage and 200ma short circuit current. Though they are connected in parallel in this project, the total current obtained is around 800mA when shorted. more than enough to play my mini mp3 player all day long.
First i've sketched it on paper and later transferred the design into a 3d solidworks model to decide parts' dimensions and simulate to make sure it would fold properly when finished
Step 1: Preparing parts
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The folding panel consists of 4 nearly identical plywood panels of 3-4mm thickness with the dimensions below. My solar panels has got a 139mm diameter so I've made the dimensons of these plywood parts to suit the panels. If you use different panels then you may need to alter the the dimensons for plywood parts.
at two of the plywood parts there are slots for the usb sockets. the other two ply parts lack these slots. There is a folding usb hub sold on the market, the usb sockets salvaged from it can do the job or you may use any other usb socket at hand.
cut the plywood parts and place them as shown in the photos, place other parts onto them to make sure they fit properly.
notice the extra plywood layer glued under the hinges which will enable the panel to be flat when folded.
Step 2: Making Electrical Connections
in my foldapan, all panels are connected in parallel over a schottky diode for every panel. To transfer power between 4 parts, the hinges are used as electrical conduits. This helped me to get rid of unnecessary cable connections between panels. I've replaced the tin hinges in the privious step to silver coated brass hinges in this step to ensure better conductivity, better looks and rust-free hinges later on.
there are two power channels in my product; one is directly connected to the panels via diods and the other is regulated by a 7805 to give 5v DC for charging more sensitive devices.
Step 3: Testing
The panel is able to run the mp3 player alone all day,
or charge mp3 player and cell phone together.
can even play mp3 while charging the phone as long as the volume of the mp3 is not too high.
Step 4: Gluing & Finishing
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When folded, the foldapan becomes 1 fourth of its open size and can fit into any bag.
after testing, I've glued the panels on to the plywood panels, sealing electrical connections and fixing the sockets into their places permamently. I've applied superglue onto the nuts and bolts to prevent them getting loose later.
Well thats it, I'm still using the foldapan after 4 months. it is running great.