Question about current draw + diode + crystals:

So here's the deal: I have recently purchased a green laser that is of much higher quality. It got here today but I don't have an 18650 to power it with. I did find in my battery pile a 14500 that gives 3.6v. Not the 3.7-4.2 the 18650's give, but something anyway.

Here's my question:

When I used the 14500, the LED was somewhat dim and there was no output. I measured the current draw and it bounced around between 90mA and 120mA.

I DID use my cellphone camera to see there WAS actually output of some kind, but it looked IR based. Now it wasn't terribly bright but here's where my questioning comes in.

Is it possible that a greenie 808nm diode will put out some small amounts of IR before hitting a threshold where the crystals will actually start putting out green?
In other words, with a low mA, if I can see IR using a camera, is this basically broken or is there a possibility that the diode is trying to draw more power but because it can't, it isn't getting to the threshold where it'll lase properly?


Here's a pic just for reference:


I'm waiting for my 18650's to come in the mail so I can REALLY test this sucker out, but I'm curious if this is a sign of a broken laser or if it's just me being paranoid.

Out of curiousity, what would/should the mA be on a greenie with a pretty reliable output of 200mw?

Here's a pic just for reference:

enigmahack said:

Is it possible that a greenie 808nm diode will put out some small amounts of IR before hitting a threshold where the crystals will actually start putting out green?

Click to expand...

Yes. It will probably still work with a better battery.

Thanks for that reassurance

I understand that a diode is like a resistor up until a certain threshold, and then the resistance drops a lot allowing current to pass and it starts to kick out the power. I suppose I just need a better battery to make sure it's reaching that threshold.

Sweet... Now I wait for that battery! Lol

The current draw from the battery should be 1.2A-1.4A for a freshly charge 18650. I don't know if your 14500 can handle this kind of power but a 18650 should work perfectly.

Hey - thanks for the reply Blord

Yeah - I realize that it should be MUCH higher, I wasn't as much questioning if the laser works... But more the WHY it isn't.

Only getting 120mA tops explains a lot lol. When the 18650's come in, I'll be sure to test it fully

Just for the sake of updating the thread in case this gets searched in the future:

A new battery makes this thing SCREAM (In a good way)

I tossed in a battery that actually HAS power and this is amazing. It's totally the power or lack there of that was causing the issue. New battery - New laser experience!

Thanks for sharing your experience. I think the 14500 normally should be able to handle the required amperage, so probably it was retired or not charged. (the printing "3,6V" actually means a nominal value, like "12V" on your car´s battery. The "12V" actually will be somewhere at 13,8V when the car is running, and the "3,6V" will be nearly 4,2V if fully charged and not under load.) Maybe you also hat a bad connection, as the 14500 is short and may need some DIY to get contacted.