LED Tail Lights

Cree XLamp® XR-E LED (P2 bin)

I had some extra Cree XLamp® XR-E LEDs (P2 bin) when I upgraded some flashlights to Q5 bin LEDs.

When I found a LED circuit board that had an input voltage of 4v-18V, I thought it would work well as a driver for an automotive LED bulb. The circuit board uses a Micro Bridge Technology PT4105 (PDF specs) step down LED driver.

I took an 1156 bulb to use as a base for the circuit board and LED. I broke out the glass and filament and used JB Weld to glue the components together.

BMW Bavaria Tail Light

The LED was brighter than the 1156 bulb, but it had a noticeable hot spot, even though the Cree LED has a 90 degree viewing angle. Heat doesn’t seem to be a problem; the Bavaria’s light socket dissipates the heat well.

Joe Weir, on the Senior Six Mailing List, suggested using a diffuser lens. I’ll have to find something then report back.

Cree XLamp XR-E LED

Cree XLamp XR-E LED

I just received a bunch of flashlight parts I ordered from Kaidomain.com. Among them, four Cree XLamp XR-E LEDs, Q2 and Q5 bins. I thought I’d mod my Ultrafire C2 flashlight that has a P4 bin Cree with the Q5. I can’t tell the difference between the Q5 and Q2 by looking at the two. I guess I have to do some kind of measurement of current and light output. The Cree XLamp LED Q5 will put out 107 Flux (lumens) when driven at 4 amps – that’s very bright.

One of the four LED’s seems to have a manufacturing defect – see the material in the upper left corner of the chip in the photo?

Two people who offered me help on the Candlepowerforums.com came up with different answers. jtr1962 says it’s the result the dome is starting to detach – he called it internal separation of the silicon filler. WeLight theorized that it was a manufacturing defect and I should return it. I don’t know much about these high power LED’s but I’m learning.