Battery Pack options for Dual 445 A-140

I'm figuring out how long I can safely run my diode with a solid 1" Diameter aluminum heat sink, and while I'm figuring all this out I'm looking for a good battery pack option that may be better than what I'm using.

My driver circuit is the typical LM317 based one, powering a 445nm (A-140) diode in a radio shack project box with about a half an amp (used a dummy load) allowed to the diode, with 9v into the LM317 from six (regular) AA batteries. Soon I will have a second diode running next to the first for a dual beam (or combined if I can).

In case it helps, when I tested the output (late) last night, the diode maxxed out at 589mW - as tested with a laserbee 2.5W.

The second test was a little lower... and I suspect that I could get the battery pack to hold it's current supplying ability and last longer if I switch to lithium ion batteries, in fact I'm not convinced the slightly used batteries I had were able to give me the highest reading. Unfortunately I'm at work and can't switch em out with fresh batteries..

regardless, I'm contemplating using 1.5v 2900mAh Li/ion AA batteries I've found on the net (just under $2 a battery) but I am not opposed to larger batteries or "better" (smaller?) batteries.

Does anyone else have advice as pertains to li/ion batteries? I keep reading about these diodes safely handling higher currents by being "pulsed" and I wonder if I shouldn't be learning more about building a pulsed driver circuit? Then maybe I wouldn't need so much battery and could run cooler...

I apologize for being all over the place, but I'm having the time of my life with this new hobby. I'm still learning, (no more burning diodes), searching these forums, and asking questions as my time permits and even donating to the board. I've gotten great advice so far and I hope more people help keep the board up by donating.

Thanks,

Cad602

Just to clarify, I want to be able to use the same battery pack to power two of the same diodes (445nm a140's) - with a separate LM 317 driver circuit on each diode obviously - for at least a few minutes at full power, much longer at lower powers....and I'm hoping someone has used Lithium Ion Battery packs to do something similar who could verify that 9volts is enough with the right batteries or if I need a different battery type altogether.
Thanks,

cad602

Cad602;

You would be better off with 2 #18650 lithium ion cells.

That would give you ~ the same capacity with 8.4 VDC.

The lower voltage would generate less heat with the dual 445 LD's.

I would use a low-dropout regulator,

instead of the LM317.

LarryDFW

I'd use 3 LiIons in series, an then drive the two 445nm diodes connected in series as well, off the same driver.

Thanks for the suggestions, I am intrigued with the prospect of driving two off the same driver - I think I've seen a thread on here with someone doing that...I'll go check it out.

I will be building another test load so I can verify that I'm not going to fry anything. And I'll be ordering some batteries tonight...

I've seen some information on here that helps a little but it's not the thread I stumbled upon in the past that had the same set up.. but I'm not too worried, I think I've more or less got it all figured out.

For now the circuit will use the LM317 though I suspect I need to graduate to some of the other regulators I've seen discussed here.

Cad602