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Been Running Blue Laser Without Driver For Hours Of Run Time(Power increased)

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So I decided to run an older Chinese laser module straight off 2, 3.7V lithium ion batteries in series without any power supply. The power output majorly increased from 3.8 watts to 5.4 watts(Yes I have an LPM).

Though the module obviously gets hot much quicker, I haven't had any problems so far whatsoever after hours of run time(Of course not running much more than a minute per session). Everything seems fairly stable and the power output continues to stay the same.

So what's the big deal with using a PS/driver? As long as your batteries are supplying the right voltage and current it should be okay right?
 
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GSS

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Are you sure it doesn't have a driver in the module.
Pic's??
 
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Here's a shot of the power reading. The module is put back together and attached to my laser gun. The highest this thing ever outputted before was 3.9 watts.

laserreading.jpg
 

Alaskan

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The power probably increased because you don't have enough heat sinking to keep it stable (for that diode, it might do that with a huge heat sink, I don't know), that is the concern and why we use constant current drivers, to make sure the diode doesn't go into thermal runaway and pull so much current it overheats and is destroyed, but it appears your battery drains down fast enough that doesn't happen.

I have done the same thing using a Coherent FAP800 and a Cyclon 2.1 VDC (when fully charged under load) starved electrolite lead acid battery, with mine, as long as the FAP was heat sinked well enough, it never became hot enough to have the current rise and destroy the diodes in the array, but at the same time, I was powering a 40 watt FAP using a 50 amp hour lead acid battery which was being drained down at a fast enough rate that the current was continually trailing lower and lower. At least for that FAP, the heat sink and battery was matched well enough to the capacity to run for about 10 to 15 minutes at close to full power without a constant current driver, and I did so many times without any apparent degradation to the device. I went up to 20-25 minutes, but the power was reducing more and more to be about 50% output due to the battery voltage being reduced too much and that's where I stopped to recharge.

There is another diode you can run without a CC driver, that is the 50 mw Osram PL520 nm single mode laser diode, I was able to run that using two Li-ion batteries and not kill it, when heat sinked well enough and possibly, some voltage drop in the wiring helped, don't know. That was with MY particular diode, I would not go as far as to say they all would survive.
 
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The power probably increased because you don't have enough heat sinking to keep it stable (for that diode, it might do that with a huge heat sink, I don't know), that is the concern and why we use constant current drivers, to make sure the diode doesn't go into thermal runaway and pull so much current it overheats and is destroyed, but it appears your battery drains down fast enough that doesn't happen.

I have done the same thing using a Coherent FAP800 and a Cyclon 2.1 VDC (when fully charged under load) starved electrolite lead acid battery, with mine, as long as the FAP was heat sinked well enough, it never became hot enough to have the current rise and destroy the diodes in the array, but at the same time, I was powering a 40 watt FAP using a 50 amp hour lead acid battery which was being drained down at a fast enough rate that the current was continually trailing lower and lower. At least for that FAP, the heat sink and battery was matched well enough to the capacity to run for about 10 to 15 minutes at close to full power without a constant current driver, and I did so many times without any apparent degradation to the device. I went up to 20-25 minutes, but the power was reducing more and more to be about 50% output due to the battery voltage being reduced too much and that's where I stopped to recharge.

There is another diode you can run without a CC driver, that is the 50 mw PL520 nm single mode laser diode, I was able to run that using two Li-ion batteries and not kill it, when heat sinked well enough and possibly, some voltage drop in the wiring helped, don't know. That was with MY particular diode, I would not go as far as to say they all would survive.

Hm, I figured the power increase was because its original driver was set at a lower and more safe current for the diode, but now with the batteries hooked up directly there's nothing stopping the current from flowing a full capacity from the batteries?
 

Alaskan

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There is a voltage drop across the laser diode and an impedance which limits the current, initially, but as it warms, that resistance decreases and when that happens, more current can flow, if it gets too hot, laser diodes typically draw more current as they get warmer and warmer and can go into thermal runaway until they burn out due to the amount of power being produced. Some diodes will get dimmer if they get too hot and I assume, then the temperature goes down along with reduced thermal runway, but some just get brighter until they die. The Osram PL520 will get dimmer if you over current, but I haven't done any thermal tests to verify it is really better off, for all I know, it is just as hot and damaging to it after a period of time. Go too far with the current after it dims, and I expect, it will die in a short period of time. Just saying, since I opened that can of photons.
 
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paul1598419

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Is that LPM the one from laserpointerstores? That is one very cheap LPM and I would not trust it to give an accurate reading. That is the only one I've seen that incorporates the TEC into the LPM case. Just a very poor design.
 
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Is that LPM the one from laserpointerstores? That is one very cheap LPM and I would not trust it to give an accurate reading. That is the only one I've seen that incorporates the TEC into the LPM case. Just a very poor design.

It's been perfectly accurate against other LPMs in videos I've watched with the same pointers... So that's good enough for me. Do you have any actual evidence that it's inaccurate? Or do you just assume this?
 
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paul1598419

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There was a thread discussing this LPM and, though I don't own one, it was shown to be inaccurate. It doesn't even have OP amps in its circuitry to keep it zeroed and linear. Just a couple of resistors as I recall.
 
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There was a thread discussing this LPM and, though I don't own one, it was shown to be inaccurate. It doesn't even have OP amps in its circuitry to keep it zeroed and linear. Just a couple of resistors as I recall.

Regardless, I really don't see how this applies when such a massive power difference was shown, 3.9 watts to 5.4 watts is very significant. the beam is also far brighter and burns a lot more. I took many measurements of the 2 powers and got consistent results, so that's really all that matters. Most high watt blue diodes can be pushed way farther than they are rated for.

Pretty far from the point here...
 

dikcheze33

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I have the worlds most powerful lazer I buy on dbay and it runs fantazimo with extra batteries, I think you don't need a driver
 
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I have the worlds most powerful lazer I buy on dbay and it runs fantazimo with extra batteries, I think you don't need a driver

The worlds most powerful laser is 2,000 trillion watts and likely costs many millions hehe. Do you mean the most powerful single visible diode laser? That currently stands at just 7 watts as far as I know. Is this a laser pointer? Or did you just buy a diode and heat sync? Also, some laser pointers will increase in power if the batteries are not supplying enough power.
 

dikcheze33

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it is THOR and is the worlds most powerful lazer, it can burn anything and I know, it is the very best you can buy
 
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it is THOR and is the worlds most powerful lazer, it can burn anything and I know, it is the very best you can buy
Lol... The Thor pointer goes to 5 watts max. It most likely has a driver/power supply inside. Otherwise it would be smaller. I actually recently ordered the green 1 watt Thor.

Try not to fall for all the marketing that says "WORLDS MOST POWERFUL LASER!". They most likely are not the most powerful visible diode. There actually aren't many pointers using the most powerful diode which is the 7 watt NUBM44. The "Sanwu Striker" is one of the few that uses it, and is actually a sponsor of this website.

After small laser diodes there are industrial Co2 lasers and fiber lasers which completely dwarf little diodes in terms of power output.
 




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