Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Electrolytic caps in LED light bulbs

Status
Not open for further replies.

eem2am

Banned
Joined
Jun 22, 2008
Messages
1,180
Helped
37
Reputation
74
Reaction score
23
Trophy points
1,318
Activity points
0
I took apart some very expensive LED light bulbs (40W incandescant replacement).

They all had a 450V electrolytic just after the full wave bridge.

The bulbs cost £30.

The marketing goes that its worth paying that as they last for 10 years.

But how will they last for 10 Years with an electrlytic in them?
 

srizbf

Advanced Member level 5
Joined
Apr 3, 2010
Messages
1,995
Helped
417
Reputation
840
Reaction score
328
Trophy points
1,363
Activity points
10,985
if the electrolytic is within maximum voltage in operating life ,
no possibility of failure(assuming a good manufac company cap).

another fact is that , the 450v types should not be kept idle for months together.
you should use it everyday by having chrge (and dischrge) cycle.

probably your doubt may be due to failed electrolytics in electronic equipments , that you might have seen.

srizbf
11thmay2010
 

hakeen

Full Member level 5
Joined
Jun 16, 2005
Messages
240
Helped
44
Reputation
88
Reaction score
19
Trophy points
1,298
Activity points
2,783
Not only max voltage, but also max temperature is important. Not in LED drives, but motor drives I have seen electrolytics dried in several years due to high temperature. I can imagien with LED lighting you are going to be at hot levels., even if you have a good PCB and colling mechanisms.
 

Audioguru

Advanced Member level 5
Joined
Jan 19, 2008
Messages
9,291
Helped
2,143
Reputation
4,280
Reaction score
1,968
Trophy points
1,393
Location
Toronto area of Canada
Activity points
58,484
Look at compact fluorescent light bulbs that are supposed to last 7 years to 10 years. Many fail in 1 or 2 years.
Usually the electrolytic capacitor inside dries out due to the heat then the circuit blows up.
 

WimRFP

Advanced Member level 5
Joined
Apr 16, 2010
Messages
1,591
Helped
594
Reputation
1,176
Reaction score
536
Trophy points
1,393
Location
Netherlands
Activity points
15,026
Hello,

I also have strong doubts about the expected lifetime. LED lamps produce heat that has to be removed by conduction/convection only (so you need temperature difference). Maybe they managed to use a test setup that is far from realistic operating conditions.

When the lamps are in an armature, temperature rise will be significant in many cases. As life expectancy of electrolytic capacitors halves each 8..10 K increase, I don't believe the 7 to 10 Years, because I don't believe they use extra long life 105 or 130 degrees C. capacitors in it.

Experience over the years will tell us….
 

ark5230

Advanced Member level 3
Joined
Jun 29, 2009
Messages
858
Helped
163
Reputation
324
Reaction score
140
Trophy points
1,323
Location
India
Activity points
6,145
Low power LED lamps use Polyester type capacitors and the failure in such cases is due to other reasons. It is worth finding if it is really electrolytic capacitor rated at 450V or it is some other type where the life expectancy is high and cost too !!
 

WimRFP

Advanced Member level 5
Joined
Apr 16, 2010
Messages
1,591
Helped
594
Reputation
1,176
Reaction score
536
Trophy points
1,393
Location
Netherlands
Activity points
15,026
Hello,

I saw a (low power) lamp with polyester capacitor also. These types use that capacitor as a current limiting device (instead of an electronic circuit). Of course here the capacitor is no problem, there it was too high temperature of the aluminum cooling frame.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top