michaelvc...thanks. I understand the liability involved. I'm sure I'm going to end up buying a charger (unless the extra one at work can be used). I have actually installed a couple of electric fences around our remote camps, so I'm pretty familiar with the requirements. Bears are surprisingly easy to keep out with electric fences. I think its because they test everything with their noses or mouths - unlike livestock, which will lean against a fence.
jadude - unfortunately, bears living around people are forced into becoming nocturnal, and for such a big creature, they can be in, wipe out a coop, and back out before you know they're there. And besides, I don't want to shoot the bear. It's my responsibility to protect the chicken, not to punish the bear for just being himself.