after recharging the batteries my diode blow-up

BoskoSLO · Jan 23, 2013

Hello

After I made my first red dvd laser burner using this site:

Laser driver - It can be done

My driver was working and I set the current to ~250ma using a test dummy.ok
I soldered everything up and it worked. I was able to burn things and lit a match 2m away.Soooo. after 4 days of using the laser without problems I recharged the batteries and when I pluged them in, I turned my laser on. for first 10sec everything was OK but then buffffff.... the diode died "the diode went very very dim and u cant see the dot on the wall 5m away.

I'm using this batteries:

TrustFire Protected 18650 Lithium Battery (2500mAh 2-Pack Blue) - Free Shipping - DealExtreme

I don't know what went wrong.
Anyone has a idea?

thx in advance.

ARG · Jan 23, 2013

Did it go really bright before it died?

BoskoSLO · Jan 23, 2013

ARGLaser said:
Did it go really bright before it died?

Well, In the 10sec after i turned the laser on I was busy focusing the beam to a piece of black plastic 40cm away and possible the diode went a little brighter that ussualy and then it died.
I'm not 100% sure because it happend really fast.

Matrix · Jan 23, 2013

Okay ive done this before after charging the battery MAKE SURE you dont use it for atleast 10 minutes.

Also if its a cheap battery it can over charge so the power will be stronger and blow it out.

I also did a bit of research and read it needs 7.2 Volts now if they listed the max voltage which could be 7.2 | the batteries you bought are 3.7 volts 2 x 3.7 batteries = 7.4 you could've just over powered it. next time buy 2 x 3.6 ultra fire batteries

BoskoSLO · Jan 23, 2013

Matrix said:
Okay ive done this before after charging the battery MAKE SURE you dont use it for atleast 10 minutes.

Also if its a cheap battery it can over charge so the power will be stronger and blow it out.

This may be the case. Because I pluged the batteries into my laser build right after I unpluged them from the charger and the batteries were still warm.

I think the current stayed the same because I set the current to be ~5ohm and that should give an output of ~250mA.
Maybe the voltage killed my LM317? because this component was hot right after my laser went dim. But i have a small heat sink already on LM317 "1x1x1cm + termal paste".

+ I also have a small heat sink mounted on my aixiz housing.

edit: As far as i read about how the LM317 works is that you need at least 3V to make it work..soo.. If I connect a 5V input power the 2V will be turned into heat and maybe The batteries had for a moment to high voltage and damaged the LM317 because of heat. idk maybe i'm wrong.

Blord · Jan 23, 2013

The LM317 is a pretty robust regulator. If you set the driver correctly then it doesn't matter using full charged batteries. The LM317 can coop with 2x 3.7V or even 2x4.2V for full charged li-ion batteries. You said the LM317 has been heatsinked so it should worked fine.

Did you have a testload to test the driver for the correct output of 250mA ?

The red laserdiode has case pin that is negative, right ? Maybe you have shorted it somewhere. It is easy to hit the laser module against other components.

BoskoSLO · Jan 23, 2013

Blord said:
The LM317 is a pretty robust regulator. If you set the driver correctly then it doesn't matter using full charged batteries. The LM317 can coop with 2x 3.7V or even 2x4.2V for full charged li-ion batteries. You said the LM317 has been heatsinked so it should worked fine.

Did you have a testload to test the driver for the correct output of 250mA ?

The red laserdiode has case pin that is negative, right ? Maybe you have shorted it somewhere. It is easy to hit the laser module against other components.

I don't think that anything got shorted. I have hot glued the cables that goes into the aixiz module so i couldn't twist the wires so the + and - pins touched.
and as we know u can unsrew the part of the aixiz module where the LD is pressed into, well i have a heatsink over it and i can't turn it until i use lot of force to do it.
The aixiz housing is not touching the driver at all so as the batteries don't touch the driver or the laser module.

And yes i have a testload and i set the driver to output ~250mA "+-5mA".

Blord · Jan 23, 2013

I think your red diode isn't capable handling the current. From what speed burner did it came from ?

BoskoSLO · Jan 23, 2013

Blord said:
I think your red diode isn't capable handling the current. From what speed burner did it came from ?

16x dvd burner.
I can't find the guy who sold it to me but i know it was a standard 16x dvd burner.

Cube777 · Jan 23, 2013

Just backing up what Blord said, the LM317 CAN'T be killed by heat! If it get's to hot it will shutdown automatically and then recover afterwards. The batteries' 4.2V could have done nothing to driver. I can only think that the LD heated up to much (since you only have a small heatsink on it) or that diode couldn't handle that current and started degrading, and that 10 seconds was the last straw. Also, are you using two 18650's or just one?

BoskoSLO · Jan 23, 2013

Cube777 said:
Just backing up what Blord said, the LM317 CAN'T be killed by heat! If it get's to hot it will shutdown automatically and then recover afterwards. The batteries' 4.2V could have done nothing to driver. I can only think that the LD heated up to much (since you only have a small heatsink on it) or that diode couldn't handle that current and started degrading, and that 10 seconds was the last straw. Also, are you using two 18650's or just one?

i'm using 2 18650 3,7V batteries.
I already ordered another DVD burner "not that expensive".
And as we are talking about heatsinks. i'm thinking of buying a full round piece of allominium and drill a 12mm hole in it so the module fits in it tight + termal paste.
The small heat sink wasn't enough sadly

Cube777 · Jan 23, 2013

Can't stress enough how you need to keep heat away from that diode! Ive learned that the hard way!

joeyss · Jan 23, 2013

See red diodes drop less voltage than let's say blue or violet. That extra voltage that isn't dropped goes off as heat. That heat is what killed your dioide.

BoskoSLO · Jan 23, 2013

joeyss said:
See red diodes drop less voltage than let's say blue or violet. That extra voltage that isn't dropped goes off as heat. That heat is what killed your dioide.

But the exes voltage on the LM317 convert into heat not in the LD.
Well i just need to make a massive heatsink not like now. I just drilled a hole though the ribs of a cpu heatsink and used a little termal paste.
I need a heatsink like other people use in their flashlight hosts.

Matrix · Jan 23, 2013

dont use 2 x 3.7 batterys buy 3.6 that couldve been what burnt it out too much voltage 3.6 covers 7.2 volts.

Cube777 · Jan 24, 2013

^The batteries he bought is fine, the driver can handle it.

after recharging the batteries my diode blow-up

BoskoSLO

0

ARG

0

BoskoSLO

0

Matrix

0

BoskoSLO

0

Blord

0

BoskoSLO

0

Blord

0

BoskoSLO

0

Cube777

0

BoskoSLO

0

Cube777

0

joeyss

2

BoskoSLO

0

Matrix

0

Cube777

0

Online statistics

Forum statistics

Share this page