Hi all. I'm a newbie cave diver and looking to upgrade my primary light. I've checked the other threads but can't find what I'm looking for. Trying to determine if anyone manufactures a primary hand held that has minimum of 3500 lumens (on narrow beam), 10 degree (or less) beam, and a 3 hr burn time at 3500+ lumens. Any suggestions or must I go to a canister light? Thanks for the help!
Handheld Primary Light Options (Cave)
- Thread starter Kate F
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that light does not exist because it is not possible to build one. Anything claiming those specs is probably lying about their light output *cough, Big Blue, cough*.
this is with VERY optimistic numbers
3500 lumen =~ 35w draw
3 hours at 35w = 105w of consumption
The best 18650's out there hold 12.6w of power which means it needs 8.3 of them to run that light. Factor in some efficiency losses and the fact that you don't want to deplete past 80% and you're at 10-12 of them to run that light. The most you can comfortably fit in a handheld light is 4. Anyone that claims they are doing those specs is full of it.
10* is also very wide for a cave primary and I would recommend staying around 6-8 if you can.
The only light that is somewhat close is the Dive Rite HP50 which is handheld, 10* beam, and they claim 3500 lumen but it only burns for about 90mins on high and it's not a constant 3500 lumen.
The best handheld light out there IMO, which I may be slightly biased because I have 2 of them, but it's the LX20+. I own 2x UWLD LD-40's that are a true 4000 lumen primary light, I also own a LD60V which is 120* video spread and a true 6000 lumen. Those are big boy lights and they light the cave up like nothing else out there. One of the LD40's is essentially permanently installed in my sidemount harness, and the other is for use with doubles, as a loaner, etc. That said, I use the LX20+'s as backup primary lights, and also as a primary when I'm doing shorter dives in backmount. They have a tight spot, are easy to use, and have a long enough burn time for the vast majority of cave divers. You can easily keep a second set of 18650's for the next dive of the day and buy a high quality 8-gang charger to charge them at night.
this is with VERY optimistic numbers
3500 lumen =~ 35w draw
3 hours at 35w = 105w of consumption
The best 18650's out there hold 12.6w of power which means it needs 8.3 of them to run that light. Factor in some efficiency losses and the fact that you don't want to deplete past 80% and you're at 10-12 of them to run that light. The most you can comfortably fit in a handheld light is 4. Anyone that claims they are doing those specs is full of it.
10* is also very wide for a cave primary and I would recommend staying around 6-8 if you can.
The only light that is somewhat close is the Dive Rite HP50 which is handheld, 10* beam, and they claim 3500 lumen but it only burns for about 90mins on high and it's not a constant 3500 lumen.
The best handheld light out there IMO, which I may be slightly biased because I have 2 of them, but it's the LX20+. I own 2x UWLD LD-40's that are a true 4000 lumen primary light, I also own a LD60V which is 120* video spread and a true 6000 lumen. Those are big boy lights and they light the cave up like nothing else out there. One of the LD40's is essentially permanently installed in my sidemount harness, and the other is for use with doubles, as a loaner, etc. That said, I use the LX20+'s as backup primary lights, and also as a primary when I'm doing shorter dives in backmount. They have a tight spot, are easy to use, and have a long enough burn time for the vast majority of cave divers. You can easily keep a second set of 18650's for the next dive of the day and buy a high quality 8-gang charger to charge them at night.
halocline
Contributor
If you want a true 3hr burn time at true 3500 lumens, you need a canister light. But, depending on where you are diving, you might find that less than 3500 lumens is perfectly acceptable. It depends what is most important to you. I would urge anyone to actually try the light they are thinking of buying on a few dives before choosing. It might save you a lot of money.
Jack Hammer
Contributor
3500 lumens is pretty bright. Keep in mind a LOT of cave exploration was done on 500 to 1,000 lumens of light (that was really all that was available at the time). Personally, we've done a lot of cave diving on comfortably on well under 2,000lumens. Your eyes adjust to the light level you use. More importantly is that you are matched to whomever you are diving with to not drown out anyone's light.
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They're now called 3800 lumens, so let's do some math.
Battery is 4x 18650's, optimistically that's 3.6v*3.5ah*4cells=50.4wh battery pack and we will be generous and say that it's 90% usable which is 45wh available.
Big Blue claims 3 hour burn time which from history we know is something they don't lie about because their customers can measure that.
3 hour burn with 45wh battery means an average of 15w consumption.
Best emitters out there are going to be about 170 lumen/watt, and they aren't using those emitters, but we will assume they are because they seem to think their lights are full of magic.
170*15=2550 lumens average during the 3 hour burn time. But wait, their literature says it's 3800 lumen for 3 hours, how is this possible? Guess what, it's not, they have lied about the output of every light they have ever made, as well as selling canisters that were allegedly un38.3 compatible but still exploded and almost killed a diver, so there's that.
Now that 2550 lumens is assuming 100% efficiency, using the highest quality emitters possible. The reality is that they're probably using emitters at around 110lumen/watt and the optics are only about 80% efficient at best, so 110*15*.8=1320 lumen average which holds true with the testing that has been done about their output which look like this.
Compare that to the Dive Rite LX20 which has a constant output driver and I'll take the one that says it's an 1100 lumen light and puts out 1000 lumen, vs the 4000 lumen light that only puts out 1100 lumen after 30 minutes.
@tbone1004
That’s some pretty good analysis, brother.
I’m venturing a guess you’re an engineer.
Over the years, I’ve learned that it’s unwise to attempt to fool engineers and attorneys.
That’s some pretty good analysis, brother.
I’m venturing a guess you’re an engineer.
Over the years, I’ve learned that it’s unwise to attempt to fool engineers and attorneys.
OTF
Coney Island Whitefish Biologist
To meet your specs: canister light. UWLD or Light Monkey are top tier.
To meet a few of them in a nice handheld form: check out Nanight. Very reasonably priced, competes with or beats the Dive Rite and Big Blue options you're probably looking at, made in Sweden (not China!!) by a company with good customer service. You'll want to clamp it to a goodman mount not use their handle.
great posts @tbone1004
To meet a few of them in a nice handheld form: check out Nanight. Very reasonably priced, competes with or beats the Dive Rite and Big Blue options you're probably looking at, made in Sweden (not China!!) by a company with good customer service. You'll want to clamp it to a goodman mount not use their handle.
great posts @tbone1004
Those Nanights are nice. I haven’t dived with one but I’ve looked it over inside and out.
Robert H. Diver
Contributor
ORCATORCH D630
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