"Now, all I need is a field charger. Can someone please tell me the most efficient, lightest, most bomber, best acting, fastest charger available? It needs to work in -50* temps in the arctic as well as 120* in Big Bend in the height of summer."
Jen, temperature extremes are not good for any chemical electric storage cells, including the ones in your SE. However, the various Lithium based cells are best in that regard, and that includes both the one-shot Li cells and the Li-ion rechargeables. If you look above in this thread you will see discussion of both types. The weights and electrical capacities of those discussed are almost the same, which is to say about 3 oz. and 12 Wh. For long times out, take more cells, which are fairly light. Three Li AAs or one honking 18650 weigh about 45 g and give you another 12 Wh +/-. In very cold environments the apparent capacity of batteries declines along with other aspects of their performance. At temperatures up to 120ºF you could expect good performance.
I have been personally using both the Energizer 3AA charger and the ML102 (with an 18650 Li-ion cell). So far, so good. At -50ºF it will be best to keep any electronics close to your body, assuming you're still alive. Similarly, when the air is 120ºF, keeping electronics out of direct solar gain is a good idea.