LED batten limited duty cycle

[bernardgreen]

I installed two LED battens last week, disposing of the cardboard today I found this "limitation of use" printed on the box.

I will be notifying the supplier.

 

[fluorescence]

Ah the old LED warranty get-out clause! "5 years warranty" they are keep to print all over the box, this is the lesser spotted limitation of that, it's usually said 5 years but only up to say 35,000 hours, which is pathetic when there are fluorescent tubes out there rated to last 80,000 hours and old magnetic ballasts could last well over 500,000 hours

 

[RF Lighting]

Find me a magnetic ballast which has been in use continually 24 hours a day for 60 years.

I know full well that some of the big old ballasts were bullet proof, but I’d like to see some evidence to back up your figures.

 

[big-all]

was the caution on the box part off the sales blurb that you read before purchase
if its not part off the full description you read before purchase then its not applicable
although i suspect the conditions to any gtee offered will include it before payment

 

[SUNRAY]

Find me a magnetic ballast which has been in use continually 24 hours a day for 60 years.

I know full well that some of the big old ballasts were bullet proof, but I’d like to see some evidence to back up your figures.

I worked in a building in 90's which had about 14 2ft fluo tubes in the stairwell which had been on constantly from 1958. We changed tubes in March and October [yes 5/7 months] whether they needed changing or not. We had to change the connectors as the bayonet sockets were failing and the tubes getting harder to find stocks of.

EDIT: these were tubes in terry clips on chromed reflectors on the wall with the Atlas control gear in a remote cast iron enclosure.

 

[fluorescence]

Find me a magnetic ballast which has been in use continually 24 hours a day for 60 years.

I know full well that some of the big old ballasts were bullet proof, but I’d like to see some evidence to back up your figures.

You are quite right, and I can't provide that evidence, but I'd bet money some of the older magnetic ballasts would do them hours easily. There's no reason for them to fail if not left with stuck starters fitted, they are merely made up of varnished copper wire wrapped around an iron core after all, not a lot to go wrong! I do know of some fittings dating to about 1975 that are usually in use 24/7 and all are still going strong on their original control gear.

 

[bernardgreen]

was the caution on the box part off the sales blurb that you read before purchase

No, the supplier ( a reputable UK company ) is "having a conversation" with the manufacturer about the matter.

 

[Adam_151]

It just a another syptom of moden stuff not built to last and not repairable. I'm sure bernard will correct me, but I'm sure its possible to design an LED fitting that would last decades, I'd imagine increasing the LED count 50% to allow all of them to be underrun, along with a power supply thats a linear transformer based design with a few discrete components for regulation would be possible, it might cost twice as much though, but long run it might be cost effective if they had five times the lifespan, but they'd have to be speced, because they'd not be fitted on a competativly tendered job otherwise

 

[bernardgreen]

The item has a rated life time of 25,000 hours.

This "rating" is almost certainly the Mean Time Before Failure (MTBF) for the items Some items will have a (Time Before Failure ) TBF much shorter than 25,000 hours while others will have a longer TBF

"" LONG LASTING: 25,000 hour rating with a 2 year guarantee. ""

The 25,000 hour rating is probably the mean of the TBF ( Time Before Failure ) values for a large quantity of the item.

Maybe the manufacturer is setting conditions of use that ensure lamps with a TBF at the lower end of the range of TBF will remain working until after the guarantee period has expired.

Being "ON" for 24 hours a day for two years would be 17,520 hours. 17,600 hours could easily be the lower end of the range of TBFs

Being "ON" for 12 hours a day for two years would be 8,760 hours. A lower end TBF of 8,700 hours for some of the units is not impossible but I would consider it to be too short.

I'm sure bernard will correct me, but I'm sure its possible to design an LED fitting that would last decades,

No correction necessary. The weak point is the lifetime of the LED element. A 20 year plus life time is possible but the element would not be as bright. The light produced in the element has to pass through semiconductor layers in the element. When the element is lit and hot thermal energy causes molecules in the semiconductor layers to move across the boundary between layers thus de-constructing the LED element.

Bright LED elements have to have very thin transparent semiconductor layers and these layers are de-constructed much sooner than the relatively thick layers in dim but long life elements

 

[fluorescence]

Many T5 lamps last 20k hours alone & a decent HF ballast has a MTBF of 100k hours. I don't see how 25k hours for an entire fitting that one throws away when it fails is acceptable?