Originally Posted by H20Fidelity
3.7 volt batteries are mostly used in Ultrafire torches like this little bugger ( Link Click Here )
I'm actually waiting on one to arrive.
Check out the pics how bright they go in the listing with a couple extra volts.
3.7 volt batteries are generally standard lithium-ion ('lithium-cobalt') batteries. If you open up a laptop battery pack you'll find a bunch of these.
Ultrafire is generally considered a poor quality brand of Li-ion battery. You don't have that much choice in the 14500 size but anything containing a genuine Sanyo cell is going to be a far better choice, and will probably have around double the capacity and higher max. current (Ultrafire blue 14500s tend to actually be around 350-450 mAh).
If you really want a bright flashlight then see if you can find an IMR (LiMn2O4 or 'lithium manganese') battery in the same size. They deliver more current (but they have a bit less capacity). There is a very good forum called BLF if you want to learn a bit more and don't mind having an empty wallet.
Edited by higbvuyb - Yesterday at 7:03 am