5V USB Portable Solar Power Charger || DIY or Buy

recently i bought myself this 14 watts usb foldable solar power charger for a price of 35 euro because as you might know from my previous videos i love utilizing solar power and charging my phone with it on the go just sounded awesome after unpacking the products and having a closer look at it i have to say that i really do like its overall quality these solar cells seem well protected and the fabric with all of its stitches look pretty amazing the only question left was whether it could truly output the claimed 2.4 amps at 5 volts which is why i headed into my garden to unfold the solar charger after then hooking up a usb extension cable along with a usb tester and ultimately my smartphone we can see that the solar charger only outputs a current of half an amp at 5 volts but don't judge about the solar charger just yet because my extension cable was actually the problem without it my phone was charging with 1.2 amps at 5 volts which sadly though was still not even half of the advertised output power but in the end i have to say that i still like the products even with lower output power but i started asking myself whether i could create a similar of course more crude solar power charger that costs around the same but outputs more power which is what we will be finding out in this episode of diy or buy let's get started [Music] this video is sponsored by skillshare which is an online learning community for creatives where millions come together to take the next step in their creative journey i presented them before and i can confidently say that when it comes to learning about electronics skillshare offers dozens of interesting classes i'm still taking a class about fpgas called learn digital electronics with schematics and the basis ii fpga board by arjuna golem hossen and now i'm pretty much at the end of the class and learn tons of new things that i will hopefully use in upcoming projects you can get access to skillshare for less than 10 dollars a month with an annual subscription and the first 1000 people who sign up via my link in the video description will get two months of skillshare premium for free first off in order to create a solar power charger we obviously need some solar cells i got those 35 solar cells from ebay for price of only 30 euro and since i will later only be using 10 of them the required cells cost me around 8.6 euro apparently they can output a maximum of 4 watts at an efficiency of 17 and they come with dimensions of 156 by 156 millimeter but aside from those information we do not know anything else about the cells like the open circuit voltage or the short circuit current so to do a bit of testing i got myself a solar cell tapping wire a flux pen and solder to add the wire to the cell we have to apply flux to the front lines and then use some solder to bond the wires to it after i did this for two lines on the front side i repeated this procedure for the back sides and after i connected the front wires and back wires with one another i got a test cell that we can work with i laid it in the sunlight in my garden and connected my positive multimeter probe to the back wires and my ground probe to the front wires and as you can see we are dealing with an open circuit voltage of around 0.56 volts and by using the current measurement feature of my multimeter i was able to measure a short circuit current of only around 2.8 amps which was a bit weird the reason is that the short circuit current is theoretically speaking the maximum current a solar cell can output at which the voltage is almost zero but even if the voltage would be the open circuit voltage then the power would never reach 4 watts and according to other forward solar cells their short circuit current is almost at 9 amps instead of just 3.

So i was not sure whether i got bamboozled or whether my setup was faulty but i got no other choice than to use my ordered cells because getting new ones would take forever so let's just hope for the best and by the way i tried utilizing the three lines of the solar cell but sadly that did not change anything but anyway for now we need to increase the open circuit voltage of 0.56 volts to something around 5 volts for my smartphone for that we need to put a few cells in series in order to increase the output voltage 10 of them should do the trick but we should not directly connect these solar panels to my phone since the voltage can shift depending on the sunlight and possibly destroy something instead we need some kind of regulator that outputs a constant 5 volts i decided on this bug boost converter that you can get for rather cheap as a first test i hooked it up to my lap bench power supply set to 8 volts and continued by adjusting its output voltage to 5 volts after then soldering a chopped up micro usb cable to its outputs and plugging that into my phone we can see that it charges with a current raw of around 1.4 amps the awesome thing about such a bug boost converter is that the input voltage can vary below or above the desired output voltage without affecting it so 10 of those cells in combination with the bug boost converter will be my setup which brings us to the next question on how to protect these cells from mechanical stress because they are super brittle in my diy solar panel video i used the technique of encapsulating these cells in epoxy resin but if you're following me on twitter then you know that this story did not end well in my opinion the problem was that the metal frame was too big and held too many cells inside which would use the mechanical stability of each a solution for that problem would be to create a small frame for each cell and encapsulate it in there in order to get a nice sturdy cell so i designed this frame in fusion 360 which i 3d printed 10 times with my two prusa 3d printers and some red and blue pla filaments as soon as all the frames were done i got myself this two component transparent epoxy resin as a first test i mixed up a small batch of it through the help of a steera and then popped all of the air bubbles with the help of some hot air then i poured a bit of the resin into a frame distributed it evenly positioned a solar cell on top of the spacers to which i obviously already added tapping wire and then finish this procedure by adding more resin on top which i then also distribute it evenly and after letting the resin dry forte i have to say that the finished cell was mechanically pretty strong and according to the electrical measurements in the sunlight the voltage and current values were only altered slightly that means it was time to solder tapping wire to nine more cells and encapsulating all of them inside the 3d printed frames just like i described it before and just like that we got 10 finished cells ready for soldering my tactic was to lay two cells on top of each other shorten the tapping wire and solder them together at the end of the two wires then i placed the next cell on top but with the other side facing up and repeated this process you basically have to constantly alter the orientation of the cells in order to later be able to pull them apart like an accordion and as soon as all the serious connections were done you can of course use some rubber bands in order to keep the folded up system together and after adding the bug boost converter to the outputs it was finally time to truly test my diy 5 volts portable solar charger in my garden and as you can see it can charge up my phone even during a cloud a day with a current of around 0.7 amps and in direct sunlight we get a charging current of 1.35 amps which was apparently limited by my phone so to measure the maximum power of my system i hooked it up directly to constant loads and performed a couple of tests as you can see it can reach a maximum power of 26 watts which is certainly not bad if we consider that my diy version cost around the same as the commercial version of course you have to invest some time and there's still a lot of room for improvement like maybe a fabric protection or a hinge system that relieves the wires and folds the cells up more nicely but even after considering all of those factors i still have to say that for me this time diy is the winner and with that being said let me know what you think in the comment section below as always thanks for watching don't forget to like share subscribe and hit the notification bell stay creative and i will see you next time

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