Wazrus Australia

[Wazrus]

G'day! I've a project using low-voltage LED's. I've bought a few as samples/tests and so far, none has lasted longer than 170 hours. From my reading, it seems that's about a tenth of what can or should be, expected. The LED's aren't used in a vehicle, but on a farm road, so there's no vibration. Power supplies are bridge-rectified 12 and 24VDC, from a multi-tapped 12v or a single-wound 24v transformer.
What's been the experience of the membership with LED's? I can't really see where I'm going wrong: in fact, I don't think I am, but am slowly coming to the conclusion that cheap LED's are just that, CHEAP...and probably nasty...am I missing something???
Also, I've had problems with 12vDC compact fluorescents. One on test did just 8 hours. Geez!!
Any thoughts???
Wazrus

 

[k0ua]

G'day! I've a project using low-voltage LED's. I've bought a few as samples/tests and so far, none has lasted longer than 170 hours. From my reading, it seems that's about a tenth of what can or should be, expected. The LED's aren't used in a vehicle, but on a farm road, so there's no vibration. Power supplies are bridge-rectified 12 and 24VDC, from a multi-tapped 12v or a single-wound 24v transformer.
What's been the experience of the membership with LED's? I can't really see where I'm going wrong: in fact, I don't think I am, but am slowly coming to the conclusion that cheap LED's are just that, CHEAP...and probably nasty...am I missing something???
Also, I've had problems with 12vDC compact fluorescents. One on test did just 8 hours. Geez!!
Any thoughts???
Wazrus

Well you mentioned bridge rectified supply's.. but you did not discuss the filtering or the regulation. Are these clean 12vDC supply's?. are they homemade supply's.? Did you measure the voltage?, Are they sized to supply the current requirements. of these LED's and CF lamps.? Do you have an Oscilloscope to look at How "clean" these supply's are.?.. LED's typically last 100000 hours. You mention the LED's are on a farm road. Are they getting wet?, Lightning surges taking them out?.. Just not enough input to draw any conclusions, but 170 hours of life... No way.. Should be thousands. My experience with CF lamps is that The cheaper ones are more susceptible to surges in the voltage.. The only ones I have direct experience with are run from Mains power. Here is 120volts AC.. The better quality ones run for a long time. but cheaper ones are taken out with surge conditions. pretty easily. They are not as durable as a regular incandescent lamp, but would last many times longer if their circuit boards were not destroyed by surges.

James K0UA

 

[Stimw]

If you are dealing with power surges you could run the rectified power to a 12V battery then to the lights. That should help with the surges.

 

[Wazrus]

Thanks KoUA and Stimw
The LED's and CF's I'm using are 'package' globes, if that's the correct term, insofar as they have bayonet or ES caps and presumably are sold as 'ready-to-use' units, i.e., 'plug'n'play'. Both of you have suggested surges and that may indeed be the case. I don't have a 'scope for analysis.
I would assume, perhaps incorrectly, that the 'globes' themselves have their own internal filtering and regulating, especially as they come (presumably) ready-to-use. Is there another way to deal with the surges other than a battery, as I'm really pressed for space?
Thanks for your replies
Wazrus

 

[Wazrus]

For Koua and Stimw
By the way, the LED globes aren't getting wet! They are in totally enclosed sheet metal fittings, where a great deal of attention has been paid to weather-tightness. They are warm and snug....

 

[k0ua]

There will be no filter capacitors or electronic regulation built in to the lamps.. you need a proper filtered and regulated power supply. What is your power supply?.. you said you you had a transformer and diode bridge.. Is that all? That does not a proper power supply make... you need a large electrolytic capacitor and electronic regulation.. Go buy a proper power supply and I bet your problems go away. Here is an example:

Astron Power Supplies

Astrons have a good reputation. I have one myself. A 35 amp unit.

James K0UA