Author Topic: 120V LED bulb on DC  (Read 3222 times)

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richhagen

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120V LED bulb on DC
« on: September 29, 2014, 12:58:20 PM »
Hi, Haven't posted for a while, been busy here, but just a note that is a bit interesting.  I remember that CFL bulbs for 48V systems off of the shelf used to be quite pricey.  I have discovered that the CREE LED bulbs sold at Home Depot in the U.S. seem to work quite well off of a nominal 48V bank.  Haven't opened one up to check the guts and see the actual mechanism or if any parts are being run over spec.  I also have not measured the light output vs. power consumption, but if there is nothing too outrageous there it seems that it might be a rather convenient off the shelf lighting option for such a bank. 

Keep having fun, Rich
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Bruce S

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Re: 120V LED bulb on DC
« Reply #1 on: September 29, 2014, 03:15:29 PM »
Hey Rich !
Good to see you posting again.
I just bought one of the Phillips 60watt 120Vac LED bulbs going for around $4/ea at HD.
I was a little skeptical about them , but was a nice surprise to see the light output.
Was even more surprised to find them to be encased in plastic.
Cheap enough to give them a try on 48Vdc too, even may be a peek inside  ;)
Cheers;
Bruce S
 
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OperaHouse

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Re: 120V LED bulb on DC
« Reply #2 on: September 30, 2014, 12:36:25 PM »
If they have a little inverter inside it may be like the small electronic wall warts that work on about 50V at reduced capacity.  Did the say dimmable?  If so they would have inverters but it would be reduced power.  I've been buying 18W flush ceiling lights at COSTCO for $14 after a utility company $10 instant rebate.  LEDs are cheap but it is hard to get a nice frame and these are great.  I pull out their inverter and stick in an ebay 2577 $2 inverter that produces 36V.  It only consumes 5W then but that is plenty bright.

Bruce S

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Re: 120V LED bulb on DC
« Reply #3 on: September 30, 2014, 02:01:21 PM »
The ones I bought, yes they are dimmable. That's good to know
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frackers

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Re: 120V LED bulb on DC
« Reply #4 on: September 30, 2014, 05:01:31 PM »
Most 'high output' LEDs run anything between 20 and 40 volts (they are multiple LEDs in series) but at constant current. The built in switch mode supply is going to provide that constant current over a very wide voltage range - probably find that they work from LED volts + 10 up to 250v. Saves having different products for various parts of the world.
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PaulJ

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Re: 120V LED bulb on DC
« Reply #5 on: October 01, 2014, 12:20:47 AM »
Just tried a 220-240V 5W Philips LED (non dimmable) on 48V dc and it works ok, I'd guess a bit more than half as bright as normal.
Completely cold to touch after an extended run on 48V, it gets quite warm on 240V.

richhagen

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Re: 120V LED bulb on DC
« Reply #6 on: October 01, 2014, 01:49:08 AM »
Yes, the Cree bulbs I have are dimmable.  They work down past 32V, but the brightness does diminish. I think they are not at full Brightness at 50V, but they are very usable as lights.  Interestingly, I could switch between 120VAC here and 48VDC here on a lighting circuit with these bulbs. 

Keep having fun, Rich
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DamonHD

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Re: 120V LED bulb on DC
« Reply #7 on: October 01, 2014, 04:37:56 AM »
I wonder if you're putting extra strain on the internal regulation electronics?

if not, then you are probably extending the lamps' life by reducing the LED temperatures.

Rgds

Damon