I'm prompted to post this because of Shun's post about flash unit battery packs. For a number of years I've been using rechargeable nicad batteries in my three Nikon SB600 strobes, which just barely last me through the concert/events I cover. Recently I decided to try a set of lithium ion (non rechargeable) batteries just to see how well they work. I was more than surprised at how long they last, and especially how fast they recycle. I'm able to use them throughout the night without them slowing, and they are good for maybe two more events, a couple of weeks apart. In the long run they're probably more expensive than nicads, but I have to say, with the fast recycle time and shelf life, I think it might be worth it.