LED Dome light burns out quickly

[bman]

I replaced the dome light with an LED panel like this:

http://i.ebayimg.com/images/g/lW0AAOxyDEVScS33/s-l300.jpg

(48 - 5630 SMDs)

It works great for a few months and then they burn out a few LEDs at a time. After a year I've got 4-8 leds working out of 48. I purchased some from U.S. sellers and China sellers - same results. I used smaller panels for the puddle lights and they are still working fine.

 

Anyone else having bad luck with LED panels in the dome light?

[fedaykin]

Nope, mine still going strong, but has far less LEDs (for 30mm festoon).

I would've just thrown some Philips/Osram ones in and not worry about it.

[FAILBOT]

Have you ever checked the output voltage of the car while it is running? If your alternator is going bad and putting out a higher voltage, then it could burn out LED's that don't have a high enough current limiting resistor.

[bman]

Have you ever checked the output voltage of the car while it is running? If your alternator is going bad and putting out a higher voltage, then it could burn out LED's that don't have a high enough current limiting resistor.

 

Engine Off = 12.97 V

Engine On = 14.80 V

 

Is that too much?

 

I have smaller panel LEDs for puddle lights and they are all working fine?

[FAILBOT]

14.8 is on the higher side. I would not necessarily call that bad. Your key off resting voltage is good and normal engine running voltage usually fall in the 13.5 to 14.5 range. For example, my battery rest at 12.45 and charges at 14.45.

 

Now some cheaply made LED panel may not be designed to handle the high end of the scale you are running at or it may just be that, cheap. LED's when run within their specs, last for a long time. Defiantly longer than a incandescent bulb. I suspect the current limiting resistors in the panels you are having problems with might not be a high enough resistance to drop your 14.8 running voltage down to a sustainable usable source. This would cause them to run at there outer limits and burn out in a short period of time or immediately. The ones you don't have an issue with may be running within their limits or better built which in turn makes them last longer. If it were me, I'd either try different LED's or do the math involved for the correct resistor and add it to the circuit. Or have your alternator tested to make sure it isn't going bad. When your engine is running it's at 14.8, what happens when you rev the motor up? It may spike well over 15v and that's not good, but you most likely would be having other electrical issues as well.

 

One last piece of info. Optimally each LED should have its own resistor. This is for if the LED goes bad, it doesn't allow the extra current available to go to other LED's, causing them to burn out much much quicker. That's where the cheaply or poorly built part applies.

[bman]

I went out to the car to get something this morning - a chilly 20F - and I happened to look up at the dome light. All of the LEDs were lit?!?! Later on in the day it's warmed to 40 - probably warmer in the car.

Is there some issue with LEDs where higher than average temperatures cause the LEDs to turn off? I assume being near the roof, it would be the hottest point.