Help selecting cheap leds for a lamp

Hi,

For a lamp (one that is used on a shelf the living room, not a flashlight), desgiend by a friend of mine, I would like to make a led replacement for the current quartz light bulb.

I first wanted to use 3-4 of those $2 CREE leds. But instead of just replacing the bulb with equivalent leds, we decided that it would be interesting to have 10-15 leds, with a mix of cool white and warm white. 15 cree leds would be too expensive. So I think I may use the "epistar" leds that can be found on aliexpress that claim 100 lumen for 3W ( e.g. "this":http://www.aliexpress.com/item/100PCS-LOT-1W-100-110LM-LED-Bulb-IC-SMD-Lamp-Light-Daylight-white-warm-white-cool/724380154.html or "that":http://www.aliexpress.com/item/High-Power-led-1W-led-70-80LM-3-5-3-7V-1W-White-led-lamp-6000/1480073087.html ) , using them at 1W .

Do you know :
-how many lumen per watt I can really expect from those cheap leds ? (efficiency is not a big problem, but I need to calculate how much leds I need and what power supply I need)
-if there is a place to buy more trustable but still cheap leds (are cree Q5 available for $0.10 nowadays ?)
-how reliable those leds can be (luminosity after 50.000 hours, MTBF, ...) ? (at $0.10, I can use 20 of them at half their nominal power if it helps)

Did someone test this kind of leds and have a reliable provider for 50-100 pieces ? (I bought a $1.5 flashlight with a similar led 2 years ago in malaysia : the driver was terrible but the led is rather good with respect to the price of the complete flashlight. The problem is that I did not run it for 25.0000 hours to see if it would fail, output 0.5 lumen per watt when aged, ...)

Thank you, and merry christmas !!
tReg.

epistar is cheapest. but I don’t trust their reliability specially when used in lamps. however they will last decent amount of time.
I made a lamp with 7 LEDs (brought locally, they said it epistar) and driver. it running 4-5 hours per day since 6 months and no any issue yet. there is no noticeable brightness change
CRI is worst I ever seen. may be 65-70. I have little eye strain when exposed to this lamp.

what driver you planing to use ?

I’m using 1w generic leds from ebay (bought from other seller, but I guess they all are the same) powered by driver from ebay and they are working fine. I have one running continiously for about 3 years. Also few colorful ones running for over a year. All doing fine. You can get them really cheap.

Not sure yet : maybe I can manually match the leds and use no driver, just use an old 19V laptop charger and use 10 “3.7” leds in serie (since I’ll probably run them at half their nominal power), but there is a risk that they get unmatched over time.

Another possibility is to use a cheap high amp ajustable PSU, set it to 4V and use 20 linear regulators, though they’ll cost more than the leds :slight_smile:

If someone knows better than me (I do more software than electronic), I’d be happy to learn !

Ok, for the driver, my current solution is a 19V PSU (I have lot of them from old laptop), and three series of 5 or 6 leds each with an AMC7140.

someone has a better solution ? :smiley:

How about a 12V Multi LED Auto Bulb?