New thought's on a old subject..and bored..

[GSS]

Seeing Sanwu having a 1W 520 and claiming unlimited duty and,
older Laserbtb. claims of 15 minutes on 10 seconds off, what is member thoughts or actual experience?
Iv'e asked before on Laserbtb claims and no one who had owned one that iv'e seen has answered..

Are people now just kinda finding out sinking the drivers properly make it possible:undecided:

Iv'e run a couple 501b hosted A140's and M140's a few times to a bit over 60 seconds and felt really no heat and i'm limited to just a IR thermometer for proper heat measurement so I have no clue to how hot the driver or diode got.

RedC, seems to get up to 5 minutes with a NUM44 at 4.5A which some heavy sinking..Are you seeing diode power drop down or other methods of knowing?
NUM44 and other equal powers run hot I realize, and so do the 520's from my experience and what iv'e read..So I find it hard to believe a there's no duty cycle to follow on again there 1W 520 spiker.

Long story short, can keeping a driver at 1.8A or less give a chance for handheld to run unlimited?
What for example will be the cause of LEDing a typical M140 in a 501b host after running it long after feeling or measuring no extreme warmth at least from the outside..?
Ok, I have no need to run any unit more than 60 seconds but still curious to just how much of run time can be done...

 

[Lifetime17]

Hi GSS,
I personally can't see running these hand held's for 5 and 10 min constant. Unless there's a small fan cooling the diode. all diodes get hot and sinking only wicks away the ambient heat they produce. So in my opinion a can't see a Snow build doing unlimited as they claim. Even if the driver is sinked . Red C likes run his with no remorse for the diode as read in some of his posts. But he sinks them well and tests the duty cycle. But he's doing 5 min + or better not unlimited cycling . Just my opinion i like to play it safe, I have a mag light build for sale on my sales thread audit runs a 7300 mW's in a aluminum sink with a copper core pressed in. But that doesn't mean i would do a unlimited cycle with it.

Rich

 

[BobMc]

Very interesting question GSS. Since I getting a 1 watt Spiker and it will be under warranty and I have a charger and some new batteries, let me kick it around. Will probably shoot Sanwu a email first to confirm, but it's something I'd like to try. Will make a post if I decide to give it a go.

 

[Alaskan]

I wonder how long the batteries in some of these pointers can last before being drained so far down the laser quits, maybe a built in safe guard.

 

[BobMc]

I wonder how long the batteries in some of these pointers can last before being drained so far down the laser quits, maybe a built in safe guard.

I know Sanwu says they have low voltage protection circuit on their Spikers. This sounds like a interesting test. Would be nice to try unprotected batteries to see if this circuit kicks it? Going to run it by Sanwu first ( don't want to lose my investment ) but am curious just the same. :thinking:

 

[GSS]

Very interesting question GSS. Since I getting a 1 watt Spiker and it will be under warranty and I have a charger and some new batteries, let me kick it around. Will probably shoot Sanwu a email first to confirm, but it's something I'd like to try. Will make a post if I decide to give it a go.

You do have a good connect with Sanwu since youv'e bought a 1000 or 2 lasers from them:crackup:
Getting full support from them to do a duty test would sure be a benefit for us:beer:
Weird thing I noticed just a few hours ago is the positive side wrapping on one of my
18350 Efest was a bit melted and stretched back. I use them mostly in a C11 NUM44 build.
I guess that's another thing to watch for as far as heat and run time..

 

[paul1598419]

I don't have many pointers that I didn't build, but from what I've seen of the heat sinking it seems unlikely that these claims are legitimate. I don't run mine past 5 minutes. Once the heat can be felt all the way out to the outer heat sink, you have to wonder what temperature the diode is.

 

[BobMc]

You do have a good connect with Sanwu since youv'e bought a 1000 or 2 lasers from them:crackup:
Getting full support from them to do a duty test would sure be a benefit for us:beer:
Weird thing I noticed just a few hours ago is the positive side wrapping on one of my
18350 Efest was a bit melted and stretched back. I use them mostly in a C11 NUM44 build.
I guess that's another thing to watch for as far as heat and run time..

Haaa, not sure if I've bought a 1000 off them yet, but I know I've spent a few pay checks there.

I'll touch base with Sanwu first.

Trying to figure out how to do it, thinking of taking a temperature and LPM reading every one minute for the first five minutes. Than every 3-5 minutes after that, depending on how things are going. Or something like that? :thinking:

 

[WizardG]

The '520 B1 I have in a pen host has gotten stuck 'ON' twice now when I throw my coat in my locker @ work. The second time was with freshly charged NiZn cells in it. The pointer body got hot enough to melt into the nylon pocket lining and make the wrapping on the batteries split but it still puts out just shy of a quarter watt. I now remove the pointer from the pocket and place it on top when I stash my jacket. Tough diode.

 

[trencheel303]

I don't have many pointers that I didn't build, but from what I've seen of the heat sinking it seems unlikely that these claims are legitimate. I don't run mine past 5 minutes. Once the heat can be felt all the way out to the outer heat sink, you have to wonder what temperature the diode is.

Fallacy
feeling heat on a heatsink means it's doing its job. The clue is in the name.

I've run my laserbtb HL 100mW green for probably upwards of half an hour, in a regular "room temperature" environment, and had no problems with it busting. I also used to run my pen lasers non stop until the batteries ran out and they would get semi warm.

The only ones I didn't chance it with were the 1600mW blue I had (445 - pre 9mm) but that was partly due to a function of how likely it was to burn through something or kill the batteries. I also don't run my 589 much longer than a couple of minutes as the heat reduces its power and stability. Cyparagon did a FLIR observation of one and calculated that with its input power and observed temperature it would never cook itself to death. Make of that what you will.

 

[RedCowboy]

By the numbers a NUBM44 at factory spec is more efficient than it's predecessor at factory spec...but that's not what we are doing.

A NUBM44 with a SXD driver running at 4.5 amps output also puts out 4.5 volts for a total of 20.5 watts of energy going into the diode and 6.75 watts of energy exiting the diode as light and 13.75 watts of heat.

The 4.5 amp SXD at 12 volts in draws 2 amps, at 8 volts in draws 3 amps, so it is taking in 24 watts and putting out 20.5 .....ROUGHLY it's actually closer to 95% efficient than 90%

So between the 2 you have about 17 watts of heat and my various heat sinks depending on winter or summer can range from 2 minutes to 10 minutes, but run the biggest chunk which is just a heat reservoir minus it's surface area heat dissipation in still air or a light breeze will get hot in 10 minutes.

You need active cooling, fins with a fan or a TEC pad to fins with a fan forcing air across the surface area multipliers that fins are, what's cool is all the little waves in the professional fins to eek out every bit of advantage.

Long story short the 44 diode with 4.5a SXD is a 17 watt hand heater, plus the fun 7 watts out the front.

Now the green diodes are less efficient, that's why they pump phosphor with big efficient blues to make green rather than use green diodes.

Compare a 1w 520nm to a 1w 445nm .....5 volts at 1 amp vs. 5 volts at 2 amps.

Actually the NDG7475 running at 2.4 amps into the diode at 5 volts is drawing 12 watts and putting out 1.4 watts of light and 10.6 watts of heat plus another watt or so for the driver it's 11.6 watts of heat vs. the 44 at 17 watts of heat.

Now a NDB7875 at 2.4 amps and 4.8 volts is what 11.5 watts in and 3 watts out so 8.5 watts of heat plus the driver.

I have noticed a single 7875 will run over twice as long heat wise than a 44 in the same sink because of the surface area dissipation, the more waste heat the faster it builds up as a percentage, so it's not linear, a half power diode with half the waste heat takes over twice as long to heat up to a set limit.

But as far as the NDG7475 and sanwus big host it could run two cells down below driver cutoff before it's 115 degrees F but it will be plenty warm, also are we talking good cells or a pair of ultrafires, it could likely drain a pair of ultrafire cells.

But the NUBM44 is no joke, even a big heatsink gets warmer and warmer, but you can use a finned sink and a small fan and build a desktop with 100% duty cycle, but just aluminum surface area would have to be pretty big, now if you look at what's in the projectors remember those run at factory spec where the efficiency is higher and the waste heat is less, but still obviously significant.

Small builds are fun, but for longer burning fun a bigger sink is much better, sometimes I chill mine in the summer time but don't freeze it or you will fog your lenses.

p.s. I did not count chilling in my assessment above.

----edit-----

One more thought, a pair or cheap 18650's will drain to under driver cutoff in less than 5 minutes, this is why I like good quality 26650 cells and 3 of them, I have started putting little volt meters in parallel with the driver input to watch battery sag and see when I need to recharge or replace cells.

I like sanwu and the spiker looks beefy, but how hot would it run in a 70 degree room connected to a power supply, well look at the rooftop continuous duty lasers, they are substantial waterproof behemoths with fins.

 

[paul1598419]

Fallacy
feeling heat on a heatsink means it's doing its job. The clue is in the name.

I've run my laserbtb HL 100mW green for probably upwards of half an hour, in a regular "room temperature" environment, and had no problems with it busting. I also used to run my pen lasers non stop until the batteries ran out and they would get semi warm.

The only ones I didn't chance it with were the 1600mW blue I had (445 - pre 9mm) but that was partly due to a function of how likely it was to burn through something or kill the batteries. I also don't run my 589 much longer than a couple of minutes as the heat reduces its power and stability. Cyparagon did a FLIR observation of one and calculated that with its input power and observed temperature it would never cook itself to death. Make of that what you will.

You missed my point entirely. These diodes are pushed many times to their absolute limit. Of course the heat sink is doing its job, but the optical thermometers have been shown to not accurately show the temperature of diodes. It is true that some builds hold up well to the heat. I built 5 MS Envies with brand new m140 diodes set to 1.8 amps. Each one was over 2100 mW and the guy I built them for had one in his coat pocket that got switched on and ran the batteries down, but still worked. This doesn't mean that it will happen every time, because, as I pointed out, these are often pushed to the limit. If you are going to test the temperature of a diode in a heat sink it is better to use a high quality thermistor to do the measurement.

 

[RedCowboy]

I think I read somewhere that sanwu lasers or at least the 100% duty cycle rated ones have the driver setup to reduce power if the laser becomes too hot, this could be how they qualify them as 100% duty cycle, but I would still avoid running one uncomfortably hot.

Here in DTR's videos you can compare a large heat sink to a smaller one.

 

[dden4012]

I would like to see how the copper core comes out of the aluminum host on the spiker. The battery contact looks glued in so there might be short wires or hopefully a spring contact to the diodes. I have been tempted​ to find out but would prefer someone else tell me. So if the driver or diodes eventually fails the host could be repurposed. It's a great host just not sure what's going on between the battery contact and the diodes.

I have an M140 that's going through my torture tests. Approximately 100hours accumulatively run off a power supply. Using a heatsink from a MX900 build made of aluminum I have ran it for hours between 0.5a and 2.3a. It just won't die. I have ran it to the point it was very hot and was fading in output for hours. I'm curious to see what it's output is at baseline amps. I use it to light my game/hobby room. No fan used just normal room conditions.

 

[Benm]

There is no mystery or magic here, it's simple science.

Two things are at play here:

1 - thermal mass of the heatsink
2 - thermal resistance of the heatsink

An example of #1 would be a big copper block that you install in the head of a flashlight host, with no fins or anything. This block will gradually heat up and keep heating up until the temperature becomes unsafe for the diode. The bigger the block the longer this takes, but it will overheat at some point.

A good example of #2 is a heatsink that has a lot of surface area, with fins, perhaps even a fan blowing on it. The laser diode will heat up to some temperature above ambient but remain there even if you run it for a century. This is bascially how things like cpu heatsinks/fans are designed for desktop computers.

Adding thermal mass can be useful for a laser that cannot be cooled adequately given the size of it's housing. It does not alter the acceptable duty cycle though: adding thermal mass can change it from 10 seconds on and 50 off to 20 seconds on and 100 off, or anything like that.

Something like 15 minutes on, 10 seconds off, is completely idiotic and probably chinese marketing. It effectively means that you can run it for 900 seconds but then need to power it down for 10 to let it cool down. If they turned down the power by 1% it would be fine for continous operation as long as the diode (or more likely batteries) last.

If you sell/market something with a 90 or 99% duty cycle, you are an idiot. It would only take a -tiny- reduction of power or increase of heatsinking to make that device capable of continous operation.

Personally i think all laser pointers that are not capable of continous operation are ill designed. I could justify it for a CNC machine where this performance is not required, but otherwise, back to the drawing board, possible with a slightly larger piece of paper.

 

[paul1598419]

Personally i think all laser pointers that are not capable of continous operation are ill designed. I could justify it for a CNC machine where this performance is not required, but otherwise, back to the drawing board, possible with a slightly larger piece of paper.

I haven't personally built any, but many members here have made a point of putting high power diodes into small, even pen, hosts. These have far less than an unlimited duty cycle, but are they failures? It depends on your point of view.