[RE-wrenches] DC power for LED lighting

[Jason Szumlanski]

Edison is screaming "I told you so." Here we are, converting DC to AC to
DC to provide lighting. Damn you, Tesla! J

 

I got the same line from an LED manufacturer. They will only warranty
the lights using their 120VAC power supply. 

 

If you want to go forward, check out Glacial Power's LD series DC-DC LED
Drivers. I've never used them, but it seems to be a possible solution.
Someone told me that Texas Instruments is big into the LED driver
market. You might start there.

 

Jason Szumlanski

Fafco Solar 

 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jeff
Yago
Sent: Friday, December 16, 2011 1:25 PM
To: conradg at cape.com; 'RE-wrenches'
Subject: Re: [RE-wrenches] DC power for LED lighting

 

I have a local sign company that asked is to provide a solar lighting
system for a double sided sign they were building for a large retirement
community entrance.  We have provided many solar lighting systems just
like this over the years and sent them several examples.  All our
systems have been turn-key in that we provided the 12 VDC ground mounted
LED flood lights with the separately pole mounted solar module(S) and
battery/controller box.   We "assumed" when we told them our system
includes the LED lights that they understood that we were providing the
lighting.  

 

Unfortunately, when we arrived on the site to install the solar system,
they said they did not need our LED lights, they wanted us to power the
LED lights inside the sign.  We opened up the signs and found two 120
VAC electronic LED power supplies.  Each was clearly labeled as
providing a maximum of 5 amps at 12 VDC output, and each powered a
separate string of about 150 tiny plastic "blocks" and each block
contained 2 small LED lamps.   We immediately advised the client that
the solar  system was designed to power our two  12 VDC flood lights and
we would have to totally tear out what we had just installed and go to a
much larger system that included an inverter, larger array, 120 VAC
timing device, and replace the 2 conductor DC underground wiring  with
3-conductor AC wire and all  this would really increase $$$.

 

I said as an alternative, why can't we just cut out the two
electronic120 VAC input  LED drivers since we are providing well
regulated 12 VDC power direct from the GEL battery.   He checked with
their LED lamp supplier and they said they strongly disagree and will
void warranty.  Since we are talking about almost 300 total LED devices
my client is afraid to give us the OK, even though we did run them
overnight and everything worked just fine.   As I recall, an LED needs
something in the circuit to limit the amp current, not the voltage
flowing through it,  or it will just get brighter and brighter and then
fail.  However, I thought almost all strings of separate LED lights
already had some kind of regulator built into each light block otherwise
those near the end of the string would be less bright than those near
the power source.    Is this correct??

 

Finally, if strings of LEDs require some kind of voltage or current
regulator, I can't believe they all have to run on 120 VAC as indicated
by this LED manufacturer who offers no alternative.    Any LED experts
out there that can point me to some type of DC-to-DC converter or
current  regulator that can replace these 120VAC LED drivers?

 

Thanks,

 

Jeff Yago

 

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