LED lights fried?

[JohnnieB]

Here is a chart for estimating the projected lifespan, amp flow and light output of an incandescent bulb when it is ran at voltages different than what it is rated at.

Running a 12V (nominal) incandescent bulb at 16V (nominal) is a 33.3% increase in voltage, so the lifespan is multiplied by a factor of about 0.035.

Therefore, if the bulb's projected lifespan is 5,000 hours at 12V, its projected lifespan is about 175 hours at 16V.

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On the other had, LED bulbs are a different can of worms.

A bare Light Emitting Diode operates at less than 5V (some colors and types as low as 1.9V), so a LED light fixture that is designed to work at 12V has a voltage reduction circuit built into it to reduce the 12V input to the low voltage the LED elements need. There is a huge variety of voltage reduction circuits used and some can only operate over a narrow range of input voltage while others can operate over a very wide range. Ideally, the fixture should be labeled with the voltage range it will operate in, but you will probably have to do some research to find out what the acceptable voltage range for a LED fixture is.

I'm kicking around the idea of adding a couple of 27W 60° LED floodlights to my cart, not so much to see better at night as to be better seen during the day while driving in town.

Amazon.com: SHANREN LED Work Light Lamp Off Road High Power ATV Jeep 4x4 Tractor 27w 60 Degree Flood Light: Automotive

Amazon.com: SHANREN LED Work Light Lamp Off Road High Power ATV Jeep 4x4 Tractor 27w 60 Degree Flood Light: Automotive

I'd run them at 12V (Auxiliary output on my TecScan lighting system), but as you can see in the specs, they can be ran with anything for 10V to 30V.

BTW: LED fixtures should have about the same brightness and color temperature throughout the voltage range they are designed for.

[radioman]

If you know how to measure current, measure it with the LED lights connected to the proper rated voltage source. Then you can use ohms law to calculate the value of resistor in ohms to drop the excess voltage of the source you plan to use and its power rating in watts necessary to keep it from getting too hot.

[Volt_Ampere]

You can also drop the voltage using diodes in series forward biased. You get about .7V per diode of drop. Diodes need to be rated for the current consumption.

[crash test dummy]

a reducer is simple

[cgtech]

Originally Posted by crash test dummy

a reducer is simple

Uhh, not to some. Some people can make a fork complicated. Not pointing any fingers here, just saying.

[Yamahaman]

Originally Posted by cgtech

Uhh, not to some. Some people can make a fork complicated. Not pointing any fingers here, just saying.

Yep

[bronsonj]

JohnnieB, I installed those exact same LEDs on a buddies Jeep. Worked great with no issues for me (yet anyway, been mounted for 3 months so far).

As to the OP question about both dimming, are they run in series? If one starts to burn out and somehow increases internal resistance and they are in series that would explain.

[JohnnieB]

Originally Posted by bronsonj

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As to the OP question about both dimming, are they run in series? If one starts to burn out and somehow increases internal resistance and they are in series that would explain.

The individual LEDs within the light fixture are in parallel, so if one burns out, the rest still work. The most common example of this is the red LED light bars used for the center brake light on many cars. Seeing dark spots where individual LEDs have failed is a fairly common sight.

Since all the LEDs in the headlight fixture are glowing dimly, the built in voltage regulator has probably failed due to a prolonged feeding of a higher voltage than it is designed to operate at. Since the tail light fixtures still work, they either have a different voltage regulator design, or they simply haven't failed yet.

[Volt_Ampere]

LED's don't have the same curve for life span vs applied voltage but they still will can overheat and fail if pushed beyond their rated current. LED's have a circuit to regulate their current. Sometimes it's just a resistor - sometimes it is a current source.