Solar Powerbank. DIY

powerbank DIY prototype

This design was created because I needed a portable 12Vdc supply to power my underwater LED fishing lights. As this is a seasonal pastime, to make better use of the project I added LED lighting and 5V USB out, ideal for camping.

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3 sides of the case

I have quite a collection of unused VHS cases, a bit large for a project like this but the solar panels I had, 165 x 135 mm fitted perfectly (totally unplanned).

diagram of connections

I'll briefly explain this prototype:

the USB charger module is the heart of this project. With this I can recharge the batteries via the solar panel or a USB mini cable.
the voltmeter is not needed I just put it in to read the charging voltage (cheap enough it can stay there)
the boost module gives me the 12Vdc I needed regardless of the input voltage controlled by switch 1, which also controls to 5V USB Out.
switch 2 determines whether I want the 12V DC Out on OR switch on the LED lights. Using this configuration saves me the cost of another switch, not convinced this was a good idea.

Time to build it ...

layout

Pretty rough I know, plonk the bits inside the case using a glue gun then solder in the wires. The holes were made by pushing a heated soldering iron tip through the soft plastic case.

Testing Prototype

Charging

via solar: yes
via USB: yes

Discharging

12V DC at RCA plugs: yes (fishing lights worked fine)
5V USB Out: yes (charged my mobile phone)
9 LED lights on case: yes

I removed the Green SMD LED from the USB Charger Module, put a 3mm Green LED on the case then connected back to the module. This gives an external indication that the batteries are fully charged.

I made a 2nd Powerbank ...

a few changes made on this one

This one definitely looks a lot better, using strip LEDs and push switches gave the project cleaner lines. I didn't use the 12V DC Out on this one, no point in having 2 identical Powerbanks.

unexpected bonus

I can remove 2 batteries and place them in my headlamp when required. Using the headlamp instead of walking around with this VHS case in hand is so much better. The 2 remaining batteries can still be used as intended, the Powerbanks capacity is reduced by 50%. The next Powerbank I make will have 6 batteries, once I obtain them.