What kind of production numbers are we talking here? $0.05 / piece difference means nothing if you're ordering 10 pcs. and shipping is $8.
I would like to produce at least 1000 of these flashlights. I am planning on initially selling on kickstarter...I can't say how successfully or successful or unsuccessful this product will be. You do make a very good point about shipping and handling and other labor being an expensive portion of the overall cost of the LEDs if production is low. I am hoping that the demand will be high enough that these factors will be minimal.
Cree LEDs are popular and liked by many for their combination of efficiency/output & decent color tints. Which is the more important thing to consider anyway: high output isn't very useful if the color tint is so ugly that nobody cares to use the light. :sick2: There's already moooorrre than enough cheap & ugly lights out there.
Definitely agree - I don't want the light output to be ugly. I compared all of the LEDs in the spreadsheet at a color temp of 3000k. All of the LEDs that I selected have a CRI of approximately (min or typical) 80. These two metrics seem like the most important standards to look at when evaluating an LED for output aesthetics. Are there other metrics that I should be looking at for light quality?
Depends on the board you use... most likely yes. Reliable depends on power levels & how well cooled the mounted LED is. Note that cooling affects efficiency & max output levels, too.
Probably going to use a metal core PCB board as a mount. Most likely this board will be a "star" form factor. Cooling shouldn't be too much of an issue as the body of the flashlight will be machined from aluminum.
If you haven't already got some in your spreadsheet, check out Nichia. They have some good color tint / high efficiency LEDs too (high-CRI Nichia 219(B) comes to mind, but possibly there's better ones out there by now).
Nichia 219B's look very efficient - approx. 125 lumens/watt @ 80 CRI @ 3500-4000K. I want to find bulk prices for these. Anyone have any suggestions on where to look?
You don't list the current / lumens for those efficiency numbers.
Are you saying that I should look at current/lumens because LEDs with a higher current for a given level of luminescence will generate higher heat and decrease overall efficiency of the light? If so, then I will definitely add that to my spreadsheet as a consideration.
What do you consider mass production? 1000? 10000? 100000? .. What percentage of overall cost is the LED?
Not yet sure what percentage the cost of the LED will be. Still in the initial stages of design and do not yet have figures for what the total cost of the light will be. The goal is to sell the light for less than $35.
Why oh why yours and not someone else's flashlight?
The optics system is what makes this flashlight unique. I can't divulge a lot of information right now about what exactly the optics entail. The overall body of the flashlight will be about the same width as a credit card and slightly longer than a credit card. the thickness is approx. 1/4".
I would consider this another way if your building a product with volume in mind. Leds constitute approx 25-30% of a products build value, going cheap on the led will mean efficacy loss is made up in the heatsink optics etc. A better approach would be to consider the impact a led has on the total build parameters and associated costs and then make a decision
Definitely like the way you look at the problem. I didn't put much thought into the heat generating aspect of LEDs. I do know that more effiecient LEDs (high lumen/watt) should generate less heat for a given light output and therefore should decrease the cost of heatsinking as well.
May i know what battery size you will be using? Xpe2 is very small and reliable . You can buy 1 roll for about 50cents per led.
Battery will be lithium ion or lithium polymer with 6-8 Watt hours.
What kind of flashlight out of curiosity?
The overall body of the flashlight will be about the same width as a credit card and slightly longer than a credit card. the thickness is approx. 1/4". Flashlight will be general purpose – it will be useful as both a handheld torch and a work light – i.e. something that you can set on the ground and aim at the area that you are trying to illuminate.
These to me seem like very odd and somewhat abstract requirements. Are you able to clarify the justification on these points? Also your list is somewhat counter intuitive, i.e.
You are unlikely to find "High lumens/watt efficiency" at "Lowest cost per LED possible".
And some of these 'requirements' would need quantifying, e.g.
"Good LED reliability"
What do you mean by this? As in reliable to what, compared to what. How are you measuring this?
I guess what I mean is that I am looking of an LED that is a good compromise between cost and efficiency. Bulk price should be somewhere in the $1 or less range. By good reliability I mean that this led should hold up for around 10,000 hours (I can't imagine too many people even putting 1000 hours on a typical flashlight) Cree claims that many of their LEDs hold up for 50,000 hours, so a 10,000 hour LED doesn't seem unreasonable.
Considering there is already a very well established preseident in the flashlight world on what LED's work well, one would have to ask why are you seemingly trying to reinvent the wheel?
I don't want to reinvent the wheel, but since the LED market is pretty dynamic I think that it is important to stay up to date on the latest LEDs and compare the quality of the newer LEDs to the established benchmark LEDs.
Also, you've made no mention to what you want the flashlight to achieve. Beam type, actual intended usage, power supply, driver type are all likely to affect LED selection.
Most of the LEDs that I have seen are in the 2.7-3.3 v range. Are there advantages to higher voltage LEDs?
As far as drivers go I haven't done a ton of research yet. I have looked at some of the product that linear offers and definitely like this:
http://www.linear.com/product/LTC3454 . Perhaps I should look at drivers first and then use the offered products to further refine which LEDs would be suitable.
The optics of this flashlight will allow it to perform as both a "thrower" and a floodlight.
Mount to what? And via what kind of process?
Mount to mcpcb via reflow soldering.
What do you mean by "reasonable price"?
Around $35 or less.
I have no idea what you mean by "mid-performance sector", maybe you expand and clarify?
By mid-performance I mean that I want this light to be perceived as good quality by flashlight enthusiasts, but nothing near as amazing as a light such as the spy007. I want this light to appeal to both enthusiasts and average people - Harbor Freight < my flashlight < Spy007. High power mode for this light would be around 250 lumens, mid power mode around 100 lm, and low power mode around 20 lm. I think that it would be good to aim for at least 2 hours of battery life on high power mode.
Thanks for asking all of these questions. You guys really helped me to better define what I want to build and the steps I should take next in the design and research process. Feel free to offer any other advice or ask any other questions that you have.
