I would encourage all to read TillyTec's technology page about HID's v Halogens v LED's, and their even more interesting battery technology info.

I though LiPo batteries were the latest, but not by a longshot, and it seems TillyTec is setting the pace in dive light battery technology too.

Now, if only they made a twin LED set for underwater video lighting that did not require I twist the lens to turn them on and off. I like my infrared on-off video housing buttons, but that requires an infrared receiver in each battery module.

Anyway, here is TillyTec's great light technology info page.