RE: JR 12X Owners - Upgrade your battery pack to Eneloops
Unfortunately, they don't sell the eneloops (at least mine doesn't). They are however nice enough to make the packs, for a fee of course.
And I wouldn't put the stock packs in the same class as the eneloops. They are not. Everyone that has used them can immediately tell a difference, in both maintaining a higher voltage longer, and lasting longer. Battery care is the same for any battery. The better you take care of them, the longer they will last.