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The Finished Solar Backpack!
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Introduction
Last year , i was trekking in the mountains and was surprised by the lack of electricity. Although there was an abundance of sunlight during the day, all lighting there during the evenings/night was with oil lamps which not only smoky but provided very little light. Vowing to return next year better prepared, i made a solar backpack. It can be also used to power widgets such as the arduino, raspberry pi, etc. Here are the features:
- Can charge upto 6 mobile phones at one time!
- 140 lumen high power led lighting
- 27wh high capacity battery
- Modular Design for expansion
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| Success! |
Materials Required:
Backpack:
- 5W Solar panel for 6v battery
- Old Bag / Bagpack
- General Purpose PCB
- Schottky Diode (1n5189/ SS14 etc)
- 6v Sealed Lead Acid battery
- 2 pin Terminal plug
Solar Mobile Phone Charger Circuit:
- 5v 3A LDO (I used a ucc383. You can use an LDO with a lower current capacity also)
- Heatsink for the TO-220 package LDO
- USB Port
Light engine:
- High Power led (Can be 1w-3w. I used a CREE XM-L as it is the most efficient led the world)
- Heat Sink for LED
- Lens/Reflector for the LED
- LED Driver
Instructions
- Attach the solar panel to the backpack. You can stitch it, use hot glue, epoxy or any other adhesive as you see fit. I used a synthetic rubber based adhesive called FeviBond.
- Using a general purpose board, construct the following circuit:
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Circuit Diagram for solar backpack
- The USB port can be used as a solar mobile phone charger to charge phones, tablets etc.
- My PCB looked like this:
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PCB of Solar Backpack
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- To make the light engine, i soldered some wire to the Cree XML led and mounted it on the heat sink.
- Although the Cree XML can be driven with 3 Amps or current giving a staggering 1000 lumens, i could not find a suitable driver. Hence, i am using a 350ma driver.
- Some LED drivers, for use as halogen replacements have a bridge rectifier.If you wish, you can remove the diodes as they cause a voltage drop of about one volt. I removed them as they reduce efficiency
- Mount the led driver on the other side of the heat sink
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| Led Driver mounted on heatsink |
- Attach the reflector or lens to the led.
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| Reflector mounted on the led |
Enjoy your eco-freindly power source! In the picture below, it is a solar mobile phone charger!
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| Mobile phone being powered by 100% solar power! |
In the picture below, the Arduino Uno is being powered by the solar backpack, making it a solar powered arduino! You can also use this to power the Raspbery Pi, Teensy etc!
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| Solar Powered Arduino |
