Really? Website seems to say 6-8 hours "or longer". Obviously 60 hours would fall into the "or longer" category, but you'd think they'd be a bit less conservative about it
Heser Tauchtechnik GmbH
On this website, the author says that at
137 hours it was still bright enough to read gauges by:
http://www.cnsales.net/ptledspecs.htm
Of course, that's the Photon Torpedo, and you're talking about the Heser, but the lights are virtually identical, and can be considered universal.
I think it's more of a "threshold" kind of thing... At what point to you decide that you need fresh batteries?
I can tell you that fresh batteries in one of these lights (with the Photon Torpedo and Heser Backup being the real performers), the amount of light coming out of these things (based on a visual estimate, not actual lumens meansurement - which seems very controversial in the industry) will make most 10w HID lights jealous... For about 2-4 horus of burntime. After 2-4 hours of burntime, the light output appears to back off about 10% to 15% (there's actually a barely noticable dropoff in performance), but they're still brighter than most lights of similar design. At 50-60 hours, the performance from these lights is similar to the cheap 3w LED "headlights" that you might find at Wal-Mart... Still very usable, but not near the performance of what you get from a fresh set of batteries.
I can totally see that, at 137 hours, there was still enough glow to read gauges by. I've never tried it, though - my "change batteries" threshold is right around 50-60 hours of burntime.
I'm confident that the company is claiming 6-8 hours of burntime because they've promised a certain amount of performance, and after that, the performance goes into a steady decline. Interestingly, unlike Halogen lamps, the light output lessens, but the light color does not change... The light is still a cool, white color - just less of it. Halogens, of course, yellow as they dim, so not only is there less light, but it becomes less usable light... Today's better LEDs like the Heser and the Photon maintain much better "usability" even as the light output reduces because the color of the light does not change.
With regard to the cave line attachment on the back of the light and using other methods... I've seen a variety of different solutions for this, including zip ties, bungee, cave line - you name it. Same with the inner tube or bungee. It's simply a matter of preference - although whatever you do, you want to make sure that it's cuttable... For example, you wouldn't want to use a key ring to attach a bolt snap to the back end of one of these lights because if you somehow became entangled and needed to cut your light free with a knife or scissors, you might not be able to do it. That's a mantra from DIR, too... No metal-to-metal connections.
The rest is really a personal preference kind of thing. I've personally found zip ties to get frail and break after a while (especially if you ever twist them), and since cave line works so well, that's what I use. Here's my favorite way of tying the bolt snaps - I use this for attaching bolt snaps to lights, tools, regs, SPGs, everything:
How to Attach a Snap - Dive Gear Express
ALL of my bolt snaps are 1/2" stainless steel bolt snaps (like the second from the left in this photo):
because that size seems to work well for everything. Your fingers get accustomed to using that size, and you develop a sort of "muscle memory" (also a DIR mantra) that really helps you be able to work efficiently when the visibility drops to zero.
When tying my bolt snaps, I always tie them VERY TIGHT. Again, that's a personal preference thing, but to me, it really keeps things from dangling too badly, which works to streamline the diver. With regards to the lights, the only reason that you'd need to remove the light from your D-ring is usually because the visibility is low and there's a lot of particulate matter in the water. When this is the case, shining a light that's connected to your D-ring can be blinding - like driving with your car's high beams on in fog or snow. Since you're looking straight down the light beam, it can be really tough to see. Photographers call this issue "backscatter." To solve the issue (and the reason why we don't use headlights underwater), remove the light from the D-ring and hold it out to the side, illuminating the area to be lit from the side... Similar to how the strobes on an expensive camera housing work. Lit from the side, "backscatter" caused by particulate matter in the water becomes much less of an issue. For this reason, I can't see an advantage in tying the bolt snap loosely to a backup light - either you'd be able to use the light while connected to the D-ring or you'd have to hold the light out to the side. Six inches of line won't help in either situation, and meanwhile would create a much less streamlined situation.
With regards to using bungee vs. inner tube as a restraint for a stowed light: Either would seem to work, I think. I feel that the inner tube is a very clean a good-looking solution, and it can be cut wide or narrow to adjust for how hard you want to make it hold the light (I like mine 1/4" to 1/2" wide). For just a couple of bucks, you can purchase a 2" wide mountain bike inner tube that'll make many little "restraints." But in the case where you don't have the opportunity to slide something like that on (and need to tie something around), I suppose that bungee would be a great solution. I think it really boils down to personal preference.
