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homebuilt camping LED using rechargeable (3.7V) Li-Po cell

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dannerpaint

Joined: Aug 22 2011
Posts: 1


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Post Mon Aug 22, 2011 9:12 am

Would like to build a fairly simple camping lantern / light from a 3.7v Li-Po cell phone battery. Wish to either charge wth solar cell, or as backup use a hand crank (generator). Question is what LED's would be applicable, and not have the added hassle of wiring on a resistor. I have connected several laying around my shop, (MOSTLY scavenged out of broken or junk devices, RE;old 3rd brakelights,blinkers and a couple out of kids toys; O don't know any ratings for individual LED's [IF THERE EVEN ARE ANY, Are they all the same????]), and none have 'BLOWN', even left some on over night. Still glowing pretty well into the next day. Would like to keep the system as simple/lightweight as possible. AND I'm pretty new to messing W/ LED's, though have fundamental understandig of Electrical Theory. [Not TOO MUCH of a *******. Any help would be Great. Thanks
paulharmo

Joined: Aug 29 2011
Posts: 10


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Post Wed Aug 31, 2011 12:40 pm

I'm always very wary of Li-Po batteries being used outside of what their exact design is. Hobbyists love Li-Po design because it can release energy very quickly, making it ideal for RC use. What's not so ideal is that they are known to smoke, catch fire, and blow up. they are known to smoke catch fire, and blow up. They're also extremely cranky about charging, so a hand crank or a solar cell wouldn't work with a Li-Po at all. If at all possible, I recommend using small Ni-mH batteries - they're much more stable, and can still be small enough to be ideal for your use.

If you don't want to use resistors, you can use small banks of LEDs wired in series. a 3.7v battery is pretty close to the average voltage for a white LED (3.2v), but to aboid shortening their life, you should hook 2 LEDs together in series. Use as many pairs of LEDs in series that you want, and voila! you have your lantern.

You could also get something like this and have the 3.7v Li-ION battery and solar panel taken care of for you. Just add LEDs.
Prescott

Joined: Nov 20 2011
Posts: 2


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Post Sun Nov 20, 2011 10:54 pm

LEDinsider suggests that it can be used to replace any household 100-120 watt incandescent/halogen bulb, although due to the size of the 12v led bulbs, you can only use in locations where a PAR38 bulb with a 4-3/4" diameter will properly fit.


Last edited by Prescott on Tue Nov 22, 2011 8:26 pm, edited 2 times in total
bad venge

Joined: Jul 28 2007
Posts: 3550


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Post Mon Nov 21, 2011 3:57 am

Yes but that will not run off the 3.7 volt BATTERY he listed icon_redface.gif
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