[jhautz]

The Extrema is what I use. The website says its 3.7 -4.2 but the new ones have an update to the software that alows it to charge to 3.6V. It works great as long as you have a power supply big enough. I fried a power supply using it once. Now I'm using a 30A PS from a big computer server that I converted for use as a charger PS.