Long life LED driver contains electrolytic capacitors.

https://www.docs.lighting.philips.c...5W_0.2-0.7A_S1_230V_S240_sXt_929000963206.pdf

We bought thirty of these units for private estate lighting of a new housing estate near Bicester, UK.
We took one apart and it had big electrolytic capacitor after the PFC stage, and other electrolytics in it.
How can it be "Long life"?

I am curious to know where the statement came from, relating the use of the electrolytic capacitor anywhere on circuit, to the LED lifespan. There are many factors that degenerate the LED, such as temperature and peak current/voltage over a specified period in the specification sheet. If on the one hand the electrolytic capacitor could be "supposed" to have some positive effect compared to other ceramic capacitors (which I doubt), its expected lifetime itself would be smaller than a ceramic kind for example, so the MTBF of the product as a whole would be inferior. I would say the question as posed is somewhat vague.

Well, "how high is up?"

"Long life" is a meaningless, non-quantitative phrase.
You may find a quantitative "life" statement on the
packaging but this is a statistical / legal thing, a
cost benefit marketing call (who saves the packaging
so as to be able to attempt getting a refund three
years from now on the "10 year" bulb?). You can bet
that the service life is oversold to know-nothing
consumers and even procurement people, who do
not dive deeper than the datasheet front tables.

I have a lot of 20+ year old equipment chock full
of electrolytic capacitors. And a lot more scrap
likewise. Who's to say, what generalized electrolytic
capacitor product lifetime effect is? It comes down
to the seal and the stress. Of course a solid state
(ceramic) capacitor is going to be more reliable to
temperature (but less so, to board flex - every
component has its weaknesses, what are the threats?).

Of course there's the small matter that you cannot,
for any money, have a ceramic 100uF 400V capacitor
that fits in a standard lamp base. So the unit with
the electrolytic, if that capacitance is necessary,
will certainly have a longer life than a stillborn design
with an unfillable BOM.

I have a selection of capacitors here, including some 'historical items' from WW2 tank receivers and transmitters. I keep them for interest, not new developments!
Most of them still work perfectly, including electrolytics and 'castanets' which older readers may remember as early versions of tantalum capacitor.

There is nothing inherently wrong with electrolytics if used properly, the issue with reliability in lighting products is they are generally run at high temperature and high ripple current. It's no worse than say red-lining a car engine 24/7. It doesn't mean the engine is faulty if it wears out in two or three years, it just means all it's useful life has been used up. Sadly many products pick components which are *just* working within their manufacturers recommended limits instead of allowing a safe margin. If I design for a resistor to dissipate 1 Watt, I don't specify a 1W resistor is used, I specify 1.5W or 2W, the same principle applies for capacitors. Kept cool and used within safe limits they last for many years.


Brian.

i came across a sight recently that said that not using electrolytic capacitors for long periods of time can adversely effect them. It didn't get into the causes but did say they could be brought back to life by applying its full rated voltage to it. Has anyone ever heard of this and how long do they have to go unused before they start degrading.

It's called "reforming". Some capacitors seem to last forever but some after long periods (typically several years) become leaky, I assume the dielectric and electrodes somehow react with each other and the insulating layer deteriorates. The trick is to charge them from a voltage equal to their rating but through a resistor to limit the current. As the reforming process works, the leakage current drops and the voltage across the capacitor rises to full. I use a resistor of around 1K to keep the current fairly low, it takes only a minute or so for them to be as good as new. Of course you can monitor the voltage with a testmeter to see when the reforming has finished.

Brian.

Yes, I used to work in a company where the product depended on a 400uF electrolytic capacitor getting charged up to 400V every second…and then being suddenly discharged through a xenon flashbulb.
When the company was just about to order a production run of say 10,000 products (ie 10,000 capacitors needed) then it would have to order the manufacture of the capacitors there and then……there was no way they could risk buying capacitors that had been in storage ..literally because the leakage current could possibly be very high in them. Even if a distributor assured them that the capacitors had only been in storage for 1 month say…you just couldn’t trust them…..because if it had been stored longer than this then the high initial leakage current could mean the capacitor blowing up.
So the company had to buy them “fresh” off the production line.
(It was sad, because this massively successful Welsh company got bullied into selling out to an overseas company. They now are not even allowed to put their own name on their own products. Having said that, nobody in UK makes capacitors any more, so no UK company can guarantee having “fresh” electrolytic capacitors. The Welsh Business minister recently congratulated the company of being an example of Welsh sucess......it was indeed a Welsh sucess..but now is sold off overseas -the minister didnt mention this....its just a matter of time before the whole place is moved overseas for good, with all the Welsh employess loosing their jobs.)