Solar Powered, LiPo to drive LED lighting

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quade
 
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Solar Powered, LiPo to drive LED lighting

Post by quade »

Background: I like the idea of being able to design something with off the shelf products that have the potential to help people. When I first heard of http://www.unchartedplay.com/new-products2/soccket, I thought it was a cute idea, but I felt the practicality of the device was somewhat lacking.

What I want to do is design a relatively low cost lighting system that could really make a difference in a 3rd world country. I want the final design to be in the $60 range, be almost foolproof to set up, require no maintenance, and provide at least 4 hours of light under normal circumstances.

I can swing a soldering iron and have built a lot of little projects, but I might need a little help in finding the optimal way of doing this as I'm not all that familiar with solar and LiPo.

Right now I'm looking at the following products available from Adafruit:

1 Watt Cool White LED - Heatsink Mounted https://www.adafruit.com/products/518 - $3.95
USB / DC / Solar Lithium Ion/Polymer charger - https://www.adafruit.com/products/390 - $17.50
Lithium Ion Polymer Battery - 3.7v 2500mAh - https://www.adafruit.com/products/328 - $14.95
Medium 6V 2W Solar panel - https://www.adafruit.com/products/200 - $25.00

I'm already at $62 without an enclosure or switch.

Questions:

Am I missing something obvious that I really need to make this work?
Are any of the components inappropriate in that they are over or under what I need to make this work?
Are there more optimal components in the Adafruit store I can simply swap out?

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adafruit_support_bill
 
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Re: Solar Powered, LiPo to drive LED lighting

Post by adafruit_support_bill »

First some rough estimates:
A 1W led (3.2v Vf) for 4 hours would consume about 1250mAh.
A 2W 6v solar panel will generate about 333mA during peak sunlight hours.
At 80% charge efficiency, you would need about 4-5 hours of full sunlight to recharge.

If there is good sun year-round, you could probably get by with a slightly smaller solar panel. You probably want to keep some reserve battery capacity to get through the occasional cloudy day.

hornerlas
 
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Re: Solar Powered, LiPo to drive LED lighting

Post by hornerlas »

Just wondering if you ever found a solution to this? i'm looking at finding a physically smaller 6v solar panel that still charges the liPo.

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quade
 
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Re: Solar Powered, LiPo to drive LED lighting

Post by quade »

If proof of concept with current items works, I'll look into sourcing a more optimal panel, but right now I'm back logged with another project and I haven't even ordered these parts yet.

I don't see a smaller panel available on the Adafruit store that would be appropriate to consider.

hornerlas
 
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Re: Solar Powered, LiPo to drive LED lighting

Post by hornerlas »

Although obviously I'd like to use an Adafruit panel, do you think this panel would work with the Charger?

http://www.hobbyengineering.com/H1660.html

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adafruit_support_bill
 
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Re: Solar Powered, LiPo to drive LED lighting

Post by adafruit_support_bill »

do you think this panel would work with the Charger?
The output voltage is a little high (the charger is rated for 6v). But the bigger issue is the current. At 20 mA, you would need about 80 hours of charging to power a 1W led for 4 hours.

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quade
 
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Re: Solar Powered, LiPo to drive LED lighting

Post by quade »

Well, yes, but I immediately dismissed that out of hand as being far too small.

80 hours of charge for 4 hours of use is . . . silly.

Not that I have anything against silly, but this device is meant to be practical.

hornerlas
 
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Re: Solar Powered, LiPo to drive LED lighting

Post by hornerlas »

No I agree it's silly. I just can't find a 6v solar panel anywhere which is small enough for what I'm trying to achieve. Apparently if you cut the bus in the tiny panel you get 80 but at half the voltage obviously.

I'll keep hunting, or start tearing apart solar powered garden lights.

verythorough
 
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Re: Solar Powered, LiPo to drive LED lighting

Post by verythorough »

What about this Radio Shack panel? http://www.radioshack.com/product/index ... d=12610002

Double the charge time, of course, but $10 cheaper and a bit smaller (3.2" x 4.3"). Not nearly as small as the one hornerlas linked.

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