Hello everybody! How do you do? This is project How-ToDo my name is Konstantin and today I'll make this power bank with solar panels. Some time ago I used to try to make a Mendocino motor, spend about hundred dollars, but its not working anyway and I put solar panels aside. Now I found it, and thinking what to do with that, decided to make a power bank.
Step 1: 3d Model
I made a model for 3d printer, its will contain one 18650 battery and two modules, 5v step up DC-DC converter and li-ion charger, I thought I need to use one more step up converter from solar panels to charger, but it's working fine without it. I always have few comments from people who doesn't have a 3d printer, but guys we live in 2017, 3d printers aren't very expensive and also you can find special websites where people who has it ready to print your model for couple dollars.
Step 2: Battery Holder
First I make brass plates for a battery holder, cut it, clean it, solder wires, glue it to the spot and fix it with battery you going to use.
Step 3: Assembly
Then I solder modules, my li-ion charger module has over-discharge protection, so circuit diagram is very simple, + and - of battery to same pins on the board, output of charger to the input of 5v DC-DC step up converter, and + and - pins near to micro USB goes to solar panels. Glue modules with hot glue, if you print with PLA filament it's a big chance to melt it, so I put aluminum plate under the model, it works like heat sink.
Step 4: Solar Panels
I use serial-parallel connection of solar panels, so on the one end it's jumper, on the other + and - output. Glue one of the panel. Final soldering - solar panels to the charger module.
Step 5: Final Touch
I know that lots of people don't like ultrafire batteries, but it's actually good if you what you buy, yes it's about twice lower capacity, but price is less then 1 dollar, show me something better? Fix battery with piece of tape. Some glue on the joints. And the final touch, now we good to go.
Step 6: Final
I'm planing this power bank as an emergency power supply, you put it on your backpack, forget for a month and if your phone is suddenly dead it'll we enough to charge it for couple calls and listen music for few hours. Thats all I got for today, hope you like it. See you soon!
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Second Prize in the
Solar Contest 2017