No offense intended. I'm not saying the coin cell powered lights aren't super handy, inexpensive and that can't provide *useful* light for a long time.

But, the coin cells don't have a lot of power in them and since they are typically unregulated lights, they have a tendency to slowly taper off in output over time. Since it is slow, you don't notice the drop off in performance.

Take a look at the runtime graph in this Photon 3 Microlight review to see what I mean (The P3 is probably better than most lights in this class due to it's multi-mode electronic control -- most other lights in this class only have one mode and their performance will look like the 'high' mode on this graph):

http://ledmuseum.home.att.net/pho3.htm

The Photon 3 has three light output modes, and on every mode except for low you see the tapering effect.

Basically, it only gets 18 hours on "high", but you'll note that the performance drops off radically in the first two hours, then slowly tapers after that. In use, it is hard to notice because the effect is slow.

'Low' mode gets pretty even performance due to it's very low draw on the battery, but while 'low' mode on a 5mm LED is 'useful' light, it isn't a lot of light.

Compare that to the runtime graphs on the Zebralight H50 (like the H30 but AA powered) where 'low' mode output is probably higher than the 'hi' of the P3, and you get rock solid output for over 3 days:

http://www.candlepowerforums.com/vb/showthread.php?t=191362

Even 'medium' mode on alkaline batteries (worst performers) nets you around 16 hours.

Part of this is there is just a lot more energy in a AA or 123A cell than the coin cells. Part of it is you gain lots of benefit from running a high output emitter at low outputs. Part of this is the regulation.

I'm not saying the coin cells aren't useful, and agree with you that they are cheap to run when batteries are purchased online. They have an advantage of being cheap to purchase and small, so you can get them for various kits.

But when it comes to long term task lighting, bigger batteries just have more energy. The H30 and H50 are a pretty sweet spot since they are small and take a single cell so are much smaller and more compact than old style AA lights. The H30 and H50 also use very modern LEDs which have come a long was as well.

Again, the coin cell lights are great. I have an e+LITE in *each* of my first aid kits for example. But my H30 is my task light.

-john