3 AAs will run a Luxeon star/O for how long?

[Joshua]

PsycoBob told me that 3 AAs will run a Luxeon star/O for a while. Hurricane Lili is headed my way and I will most certainly loose power tomrrow.

This is the only light I have in the house. All of my photon batt. are dead. So I am wondering how long I can keep 3 AAs hooked up to my LS. Thanks guys!

 

[ElektroLumens]

I left one running all night, and it still shining, but not real bright. If you use 2 or 3 ohms resistance, it will not be as bright, but will last longer. If you go with 5 ohms, it should last for a long time. Be sure it has good heat sink.

Wayne J.

 

[Joshua]

So I can hook it up without a resistor of any kind and it will be OK? Thanks for the info ElektroLumens! I really apprciate it.

 

[PsycoBob[Q2]]

Heatsinks are your FRIEND. 3 NiMH AA'a will direct-drive (my) LS @ 800mA, slowly dropping over about 6-8 hours to around 200. Still very bright. Mine os mounted to a massive aluminum heatsink- a 'Golden Orb' CPU sink, to be precise.

 

[flash....]

800mA ??? is that for a 1 watt star?
I thought 350mA was average forward current and 500mA was peak pulsed current.
Can you drive them that hard with a real nice heat sink? if so how bout a thermo electric cooler?
I have one and was thinking about trying some very carful tests.

 

[Joshua]

800ma?! I thought anything over 350ma would kill my LS/optic. I have model # LXHLNW98 180,000 mcd. How did you run yours up to 800ma? Can I safely do this without screwing up my Luxeon? I would be using 3 AA alkalines.

 

[Joshua]

Mines a 1 watt by the way.

 

[Joshua]

OK, Im gonna hook up my 1 watt Luxeon to my 3 AAs....Hope you guys knew I was talking about a 1 watt. (God I hope I don't fry this thing..)

Feel free to try and stop me if I am about to let all the magic smoke out of my 1 WATT LS/O. I HAVE NEVER DONE THIS BEFORE

1 3 AA in series battery holder from radio shack...
<check>
Good heat sink...
<check>
1 new LED 'toy' that I am willing to give up to the LED gods if Im wrong...
uhhhh..<check?>

 

[mc]

Joshua, good luck with that really big storm (cat. 5?) heading your way, hope you have back up batteries.

 

[PsycoBob[Q2]]

My 1w white LS/o will handle 800mA just fine- because it's on a freaking HUGE heatsink.

You can drive a 'bare' LS/o at about 350mA, without any problems (other than risking a burn if you touch the aluminum PCB) and a well-heatsinked LS can take truly staggering amounts of current. THe part that kills it is HEAT- and the big limit with a well-sinked LS is not the sink, but the LED die. It has a certain thermal resistance that is normally negligable, but becomes important when driving it hard.

There comes a point when keeping the back of the emmitter @ 18C will not save it- and most sinks will not keep it quite that good, unless you happen to be in a cold room. Yes, a TEC (peltier, ThermoElectric cooler, solid-state heat-pump, etc) will work, but you'll need to remember a few things. A cold-plate to mount the LS to, and to spread the cooling-effect of the TEC, a HUGE heatsink on the other side, and the minor point that a TEC is something like 5% efficient. It makes a shitload of heat, inaddition to the heat it pulls out of the cold side. (great thing to do if you want to see how hard you can drive a LS, but lousy for a flashlight- TEC's use obscene amounts of juice.)

I plan on placing a well-sinked 1w outside this winter, and seeing how much amperage it'll handle before popping. Here's what happend to my poor greenie- http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=3;t=002912#000000

 

[Joshua]

IT WORKS!!!
Damn that thing is bright!

 

[MR Bulk]

I have driven a 1W LS mounted on a tiny heatsink (1/8th" thick x 5/8th" diameter aluminum disc) using 3AA alkalines and it sucks 1.5 AMPS through it. Hasn't fried yet, and there are pert' near SIXTY of these LGIs out there being "field tested" right now.

Of course, that little heatsink is mounted to an all-aluminum Legend flashlight body that gets up to 126F max...

Best wishes and good luck with that Lili...

 

[Joshua]

Thanks Mr. Bulk, I hate weather down south. I was raised in Tucson Arizona, so I am not used to all this tropical storm hurricane stuff.

I have my LS mounted to a small all aluminum heat sink. I am only able to keep it on for about 15 to 20 seconds before I feel that thing getting hot. I did however cool down the heat sink by sticking it inside one of my frezzer vents for about a min or so.(Cold compressed air/freeon) Then when I fired it up again I was able to keep it on for about 30 to 45 seconds before it started to feel too warm for my taste. I don't want the poor thing to get too hot and 'poof' on me. Just wanted to see how bright these LS are in person. I knew they were bright from the spec sheets and the pictures I have seen on the net,
but DAMN!

 

[Joshua]

Driving my LS/O white at 800ma is like what watt wise? Is this compariable to a 5 watt LS? The spec sheet I got with this said my LS should put out 180,000 mcd. I wish I had a light metter to see how bright mcd wise this thing is now!

On a side note: I was worried about the color of the LS since I heard that the color varies so much from one LS to another. I have to say that this is the PERFECT cool color I wanted. VERY white with slight touchs of blue and a hint of purple.

 

[Vikas Sontakke]

Where did you buy your LS/O ?

Thanks,
- Vikas

 

[ElektroLumens]

He Joshua,

Just remember what everyone is saying about really good heat sink. Even a big piece of aluminum plate will work. If you are using the light for emergency, and you need it to last a long time, it's seems that you might want to limit the current a bit, to prolong the battery life. If you use 3 ohms of resistance on the 3 AA batteries, you'll get a lot better battery life. You may not need all the extra bright light emitted at the higher current, from the LS? You could try using a 3 way switch, with a low setting and a high setting. When you need the extra light, you can switch it to high. Otherwise, you can leave it on the low setting.

If you can, get a battery holder for 3 or 4 D cells. If you use a 4 D battery holder, make a dummy D cell battery, and put about 3 ohms resistance in it. This should run continously, 24 hours a day, for probably 4 days, and still give off useable light. Of course, you only need it for night time, so you could probably go for 1 week on one set of batteries.

Also, when you get a chance, buy one of the larger modified LS flashlights from one of us who do mods. Or, keep a good supply of 3AA batteries.

Wayne J.

 

[Joshua]

Well I just got my lights turned on tonight. The LS worked great! I mounted to a VERY nice heatsink that I took from an older ham radio. I stuck some ice in a ziplock bag and stuck it under the heatsink. I kept the LS/O runing all night and it never got warm. I'll post a pic of the mod that saved my *** during hurricane Lili when I get a chance later this week. I'll post it in this thread. Thanks for the help again guys!

----Joshua----