I had one of these (not the exact model but same concept) with my Mogul and TP2 and it worked very well. I used Sanyo eneloop rechargeable batteries because they have a long shelf life without self-discharge. (1.2vx4=4.8v), and it provided about 2800mAh, or enough to almost fully charge the battery twice.

I paid about $10 for the battery box, and it more than paid for itself.