Instructables

Step 6: How Long does an LED Stay On?

Picture of How Long does an LED Stay On?
With the stack of 10 pennies, I attached a green LED and wrapped it all up with electrical tape in hopes to make it air-tight.  

I set it on my shelf and watched it for a few hours to see when it would die out.

I was amazed that the light actually stayed lit for over 16 days!!  I really am impressed at how well that worked out!  

Well, there's an energy idea that's worth a few cents.

Haven't see the video yet? You can still see it here!

If you like this project perhaps you'll like some of my others. Check them out at www.thekingofrandom.com
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
Really? It's hard to believe. I'll have to give it a try sometime. :)
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
tiger125061 year ago
After the 16 days, did you check to see if the cardboard had dried out? Perhaps it quit because your electrolyte finally dried out.

Also, note that you could limit the current on your LED with a resistor (as you should be doing anyway) which should increase the run-time also.
The King of Random (author)  tiger125061 year ago
You're right, a resistor would make it last longer! At the expense of a brighter light. Thanks for your suggestions!