Perfectly well, had a couple of long nights with mine and a Striker, no problems at all, battery lasts with loads to spare.
Li Ion technology is very different to the old sealed lead acid type, even with a brand new properly charged 17A battery I was finding it would start to fade after a couple of hours, whereas the Li Ion pack stays as biright as it is when you first put it on, then it will completely die. But I have to say that I haven't run mine down so far, and I am like Jamie and his magic torch, it's on more than it's off when I'm out, I'm shit at getting over fences and ditches so