Almost anything is dangerous is used incorrectly. On the AAA/AA chargers. I got a draw full of them. We all started with the AA/AAA stuff. But, now we have graduated up to the bigger stuff. Simple as that. Just because I have a draw full of AA/AAA chargers, I am not gong to stay with AA/AAA type batteries. I have even moved passed the 18650, I am cruising with the 26650 type lights.. Oh boy...

Another thing I learned while progressing with the bigger cell flashlights. Stay away from the cheap cells. I too have some of the Ultrafire stuff. Ha, I throw them in the lights on my wife's bike. She seldom rides. Cheap cells are a joke. I found that out from experience and reading in the flashlight forums. They TEST the cells in those forums. You find out the good ones and the ones that are crap. Even got some so-called good ones but turn out to be fakes.

The good 18650 cells are going to cost you..I got some Hi Max 2600Mah 18650 cells for $6 each. They have the AW, Panasonic and a lot other quality cells out there. So do your research on that, and used the Utlrafires for starters. Also, learn the dos and don't of handling battery cells, and you be okay nothing to worry about.