Energy efficient- high brightness?

[Danz409]

this is a bit of an off topic project. still working with LEDs, i'm looking to basically make a yard/garden light with the same carbonate tube lighting element as the lightsabers.
however there is one problem... these LEDs suck down 700+ma of power! is there any super efficient drivers for them that run them much more efficient
but maintain some brightness? what is the best white LED/driver for maximum brightness/energy efficacy?

[Danz409]

i'm not seeing ANYTHING for low powerd drivers. ill just have to use my CF and limit current with R.I.C.E to experiment with. anyway. does anyone know of the best LED to under-drive?

[Silver Serpent]

Rebel Whites can be run as low as 350mA, and there are buckpucks available in that range. A little Google-fu can turn up buckpucks at 350mA, 500mA, 700mA, and 1000mA.

If 350mA is still too much, may I suggest switching to a LED string? You can get a number of accent LEDs running at 20mA each and wire them up in parallel for a decent amount of light without too much current.

[Danz409]

Rebel Whites can be run as low as 350mA, and there are buckpucks available in that range. A little Google-fu can turn up buckpucks at 350mA, 500mA, 700mA, and 1000mA.

If 350mA is still too much, may I suggest switching to a LED string? You can get a number of accent LEDs running at 20mA each and wire them up in parallel for a decent amount of light without too much current.

sadly those are still too high. as said i plan to put 2 LEDs in running 100 miliamps each *assuming the forward voltage is somewhere around 3.7 is the luman/watt ratio worse when you under drive them?

[Silver Serpent]

If you are looking at a maximum of 200mA @ 3.7v, then 10 white accent LEDs @ 20mA each, wired in parallel, would be your best option. 100mA is not enough to light up a Rebel White. There are a few good LED string tutorials in the forums, but you'll have to search a bit to find them. I think slothfurnace did one.

Another possibility would be to get an outdoor safe LED driver that you can plug into an outlet. Current would no longer be an issue if you go that route.

You get less lumens when underdriving. You'll have to experiment to determine if you're getting enough light for your purposes.

[Sevinzol]

i'm looking to basically make a yard/garden light

What's your power source? Solar panels or house current? I think Silver serpent is right, just use house curent.

I made a halloween decoration with a solar powered path light. The little NiCad AA was able to power the single accent light for about 4-6 hours (1.25V @ 20mA) but took all day to recharge those 80-120mA. You're going to need a huge solar collector and reliable sunshine in order to charge up all the MilliAmps in your battery. Either that or your light won't stay on for long

[Danz409]

yea. its basically going to be a "brighter" version of those yard lights
something that actually puts off a usable ambient light.

as for testing. i'm fine with 5x 20 miliamp accent LEDs but for a final design i wouldn't mind just a single LED die
around the power level. is there such a t hing as a "mid level" LED?

What's your power source? Solar panels or house current? I think Silver serpent is right, just use house current.

I made a halloween decoration with a solar powered path light. The little NiCad AA was able to power the single accent light for about 4-6 hours (1.25V @ 20mA) but took all day to recharge those 80-120mA. You're going to need a huge solar collector and reliable sunshine in order to charge up all the MilliAmps in your battery. Either that or your light won't stay on for long

[Silver Serpent]

There are LEDs that run on 100mA, but the ones I've seen are just the LED emitter, and no star. Check the big electronics sites and you should be able to find a few LED emitters in the range you're looking for. You'll need to brush up on your SMT soldering skills.

[Danz409]

There are LEDs that run on 100mA, but the ones I've seen are just the LED emitter, and no star. Check the big electronics sites and you should be able to find a few LED emitters in the range you're looking for. You'll need to brush up on your SMT soldering skills.

got my testing done. i did some under-driving to a luxion K3 white to 100 mili-amps and compared that to 5x 20ma basic LEDs and the brightness is surprisingly no different. though the luxion was a warmer color so if it was a cool white it may look brighter. i have ordered some 1w SMD chips and ill give those a try and see how they do.

also a lens or reflector helps greatly. so i orderd some of those as well. hopefully they give the boost needed. otherwise using a tube defuser may not work and ill have to revert to LED strips

as for drivers on the final thing. can't afford a a bunch of CF boards... so yea. what is the cheapest adjustable current limiting (or just 200 mili-amp @ 3.7)? The unit is planned to have 2 total LEDs one on each end.

[Silver Serpent]

Cheapest method is to use a resistor. I've not seen a 100mA or 200mA buckpuck or other LED driver. They might be out there, but you're gonna have to search.

It may be faster to look up a LED driver schematic and build your own.