Dimming of LED lights
Dimming of LED lights
(OP)
I have a 150W outdoor LED light fixture that doesn't turn on with 100% brightness. Appears it's only about 25% bright. Cant understand how it's possible. There ain't any dimming controls in them. Then what else could be causing this?





RE: Dimming of LED lights
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Dimming of LED lights
RE: Dimming of LED lights
I've just been playing with some cheap E27 9W LED lamps. A Philips for $2.50 easily runs at low power with a .05uF capacitor in series or 70,000 ohms. That is like a neon lamp! Looking with a scope it is a simple full wave bridge with a resistor in series and a smoothing cap. I have one in the basement operating at low power so the dog can see the steps at night.
Tried the same thing with a $2 Zilotek, an identical looking package. That unit would flash at about a half second. Obviously an electronic ballast that waits for a capacitor to charge up before the inverter starts.
Both lamps have a 9-10 year life expectancy indicating they are over driving the LED. The base of the lamps get quite hot.
RE: Dimming of LED lights
RE: Dimming of LED lights
I guess I will have to bring down a fixture to verify this.
RE: Dimming of LED lights
Not generally true. Almost all LED stop lights have either parallel strings or bypassing of bad strings. Hard to imagine that street lights would be designed differently.
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RE: Dimming of LED lights
Are these stepped brightness lights? If so the motion sensor could be bad so it never steps-up.
One of the series LEDs can fail and that restricts the current by presenting too high a resistance to ALL the other LEDs in the string(s).
There can be a bad solder joint that does the same thing.
There are usually current limit adjustment screws. It may be set wrong or the pot is bad.
Infant mortality of the driver or any one of the LEDs will do the same.
Trouble shooting: Wearing dark glasses measure the voltage drop across each LED. Make sure you do it including the wires that feed the LED so you include the connections. You do that by measuring from the terminals on the adjacent LEDs.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Dimming of LED lights
So, at this point I believe I may have to measure the resistance across LEDs.
Current limiting screws? where?
RE: Dimming of LED lights
Keith Cress
kcress - http://www.flaminsystems.com