Monday, 2 September 2013

Cigarette Tin Solar Phone Charger

Here's a little project I put together to save charging my phone through the wall sockets. Taking the excellent Adafruit MintyBoost kit, adding a solar panel and putting the lot in a nice old tin I think I've made something pretty good.

So the main materials used here are:

  • Adafruit MintyBoost V3.0
  • 6v solar panel (eBay)
  • 4 x AA rechargeable batteries + holder
  • cigarette tin

The tin I picked up in an antique shop in Hastings, a bit of a task to find the right thing but worth it. It definitely keeps with the 'upcycling' ethos.

The MintyBoost kit comes with a 2xAA battery holder and recommends only 2 batteries. I'm using rechargeables which put out a lower voltage than normal AAs, so I need 4 to get the power required to charge a phone effectively.

Since the tin is metal I had to glue a sheet of plastic to the top to prevent the solar panel from shorting out.

The next job was to make a hole for the USB socket. I used a router bit on my Dremel to do this. 

After building the MintyBoost (guides can be found on the Adafruit website) I fixed it into the tin using a piece of scrap plastic and epoxy glue. I made sure the kit worked before gluing it in, of course....

The solar panel is then glued to the plastic on the top of tin, after drilling a couple of holes in the lid for the wires. More epoxy glue used here with a couple of spring clamps whilst drying.

After gluing the battery holder in place it's time to wire up the innards. A schottky diode is required on the positive feed from the solar panel in order to pull current down to the batteries. Excuse my ropey soldering, I like the grungy look.

The negative rail is grounded out to the tin with a bit of solder and I isolated the diode with an old bit of mains cable sleeving.

All done and ready for a sunbathe to charge those batteries up.

After a couple of hours in the sun the tin is now charging my phone perfectly! So my plan is to leave the tin in the conservatory by day and top up the phone in the evening. So far it's doing just that. Brilliant!