Throwies are simple LED circuits — the LED and a battery, with an optional magnet so they will stick to ferromagnetic materials.

Evil Mad Scientist Laboratories does a pretty exhaustive analysis on the circuits, looking at battery life and potential danger of these simple circuits. Some thoughts on throwies

This data shows a couple of interesting things. First is that the power-law model seems to hold fairly well. Second, the power function that pops out is not very different from that of the data from only the first half hour– integrating both out to 24 hours gives two answers– 150 mAh and 186 mAh –that differ by only 25%. The estimate based on the long data record (150 mAh) is the more accurate one, but this does suggest that we should be able to use the data from the first half hour alone to get a fairly good “factor of two” estimate of the performance over 24 hours.