Lumen / $ Ratio Up to 800 With Dollar Tree LEDs

What's the latest on the lumen/watt ratio? When I left EE to start teaching, CREE had pushed the limits of LED tech. in the lab to 200 lm/W. That was 2011 and I am still waiting to see that one commercially available 6 years later.

About that 800 lm/USD bulb... is the reliability of the electronic ballast really 20,000 hours MTBF for that price??

-Tom Pounds

That's another thread.

This is lumen/$$$$

Feynman should have done more challenges based on nano cost, not just nano size.

's_Plenty_of_Room_at_the_Bottom

I'm considering a spread sheet competition but, not being a hypocrite, I wa nt to enter and at least make a decent showing. I may wait until prices ch ange so I win the first event.

in the lab to 200 lm/W. That was 2011 and I am still waiting to see that one commercially available 6 years later.

t really 20,000 hours MTBF for that price??

Can't say. The properly ventilated indoor bulbs haven't had time to reach

20,000 hrs. (I waste time turning off LEDs out habit.)

The enclosed and/or outdoor bulbs -- not recommended by the manufacturer -- burn out after about 2,000 hrs with a few outliers that make it to 6,000 h rs.

Two questions:

1. Why do LEDs even need a ballast or any additional electronics at all?
2. Why are electronic ballasts so unreliable in rain? At one shop the roo f leaked and dripped gallons of water onto a conventional indoor unweatheri zed 4 ft florescent tube fixture and the 700 volt wire coil ballast worked just fine for thousands of hours.

Bret Cahill