Solar Panel Backpack
Lenovo Laptop 15″ backpack ~$10
- I found a deal on this from slickdeals.net , I made sure to use a backpack with a flat back so it was easy to attach the panels.
Solar Panel – $18.15 x 3 = $54.45
- http://www.ebay.com/itm/220430473850?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 These are the panels I purchased, the diode comes with the panels. [ Some people say that China can be hit or miss for panels, because they may use broken panels, but the ones I purchased seem to work great.]
18 Gauge wire
New Trent Battery ~ 20
- Again I found a deal on slickdeals.net for this. Normally retail is higher price
Diode – IN5819
- Comes with the panels
- Used a dremel to cut it off of a USB hub
High temperature epoxy
Heat shrink tubing
I used 18Gauge wire for durability. You can solder the wires anywhere on the negative or positive. They are all in parallel.
These are connecting to a usb port. The usb port has its data connections soldered together. Some phones needs these points soldered together so that it doesn’t limit itself at 500ma, and recognizes it as a wall outlet.
These panels are charging a 5v 5Ah LiPo battery. The battery can output 500mA or 1A. This battery does not have its data connections jumped, so I made an adapter that jumps that data connections.
This allows me to leave the backpack idle, and make use of collected solar energy at night.
Measuring the panels will show about 7 Volts, but when connected to the circuit the voltage drops to 5.5 with the diode in series.
In direct sunlight the highest charge, while connecting it directly to the multimeter, I was reading ~700mA at 7V (not connected to battery, just raw feed from panels).
I used hot glue to attach the panels to the backpack. ( I would recommend using an epoxy that can handle heats in excess of 180ºF )