Silva LX

[FromTheGrassyKnoll]

Any views on the new 5W LED Silva LX

Although I seem to be spending far too much time on nopesport today....

I am interested in this. I have a home built 20w 6v halogen lamp which emits around 300 lumens but you need to do weightlifting to carry the NiCds around so I often just use a 10w bulb instead.

If the Silva LX is based on a Luxeon bright LED then it is likely that it's putting out around 120 lumens which isn't bad...

It was said many years ago, in caving circles, that the spectrum of light from a LED is actually well suited to night vision so having less lumens may be less of a problem than you think...

very interested... Could be the basis for a CompassSport review article?

[grubby]

[quote="FromTheGrassyKnoll


It was said many years ago, in caving circles, that the spectrum of light from a LED is actually well suited to night vision so having less lumens may be less of a problem than you think...

[/quote]

.>>>..not if you're looking for a tiny 'spit' (artificial belay point) whilst dangling in some dark hole or other!!

LEDs give a very 'flat' light. You'll need to take your headset off and hold it low to produce a shadow on the far lip of that Depression you're looking for. Otherwise you'll run right past it.

[Adventure Racer]

(apologies in advance for all the technical stuff - but you did ask!)

Having done a fair bit of research on this issue, and being currently in the process of building my own LED light (currently for biking - I plan to build a slightly better one for night-O, as I'm not convinced the current one is as good as a 20W Silva), I'd suggest that comparing the 5W Silva LED to a 10W halogen Silva is a little optimistic. From a theoretical lumen point of view, the 5W Silva uses a Luxeon V, which is specced to give 120lumens. A 20W Silva should really give something more like 450 lumens, or over 200 lumens for a 10W. Meanwhile my current build uses LEDs which give 130lumens each - I'm not actually convinced that even with 3 of these it is as good as a 20W (though it's pretty close) - my next build will be 4 of 150lumen LEDs, which I'd hope would be as good as a 20W halogen, though this will be 5 times as powerful as the Silva 5W LED!

Regarding weightlifting for the batteries, my current Silva battery - which is enough for 1h20mins on 20W - is a tiny thing (as grubby will attest to). Small enough that I don't use a battery carrier or bumbag - it simply fits in the front pocket of my O-pants. Weighs about 200g using LiIon cells from a laptop pack (though even the "old-fashioned" NiMH packs are half the weight of your NiCads).

[FromTheGrassyKnoll]

my next build will be 4 of 150lumen LEDs,

But aren't they 5W each... so 4x5=20w

You may as well use a halogen bulb?

Must be missing something.

My current set-up is a 20w 6v halogen bulb driven via a Voltage Regulator from NiMh batteries... It's heavy to allow me to get well and truely lost and still have light. One day I must try Lithium Ion...

[Adventure Racer]

my next build will be 4 of 150lumen LEDs,

But aren't they 5W each... so 4x5=20w

No, only 2.5W each - the very latest technology ones which are more than twice as efficient as the Luxeons in the Silva (the ones I currently have were only released to anybody a month or so ago - these slightly higher spec ones are due out in the next couple of weeks, so the first commercial offerings won't be out for quite a while yet).

Oh, and the other benefit over halogen is that if you dim them they get more efficient, so you can have efficient lower power settings using just a single lighting head. My 4 LED light will be ~11W input (allowing for regulator inefficiency), but you will get 60% of the light output (so much better than the 10W setting on a normal Silva) running at only 5W, and better light output than the Silva 5W LED at only 2W for a "get you home" setting!