Actual evidence to support the durability of LEDs.

[kr2y5]

I have always heard that LED lights are incredibly durable, and that the diode burning out is not something that one needs to be concerned about. That made them appear attractive compared to HIDs. My own experience seems to put this into question, with two expensive lights from two reputable brands having failed 3 times within the past one year. Certainly it's not enough data to extrapolate from, as I could have just been unlucky, but it's enough to make me wonder what is the actual source of the popular belief that the durability of LEDs is superior to HID, to what extent this is a fact supported by data. I don't mean here a narrowly-defined durability, as in suitability for hammering nails with it, but more of an end-to-end concept that includes the probability of manufacturing defects, etc. Have there been credible experiments, or any sort of a study that looked at the failure rates? I'm debating whether I should switch to a HID, if for no other reason than the fact that the latter seems to be a bit more of a modular system that allows for at least some repairs on my own if anything goes wrong, as opposed to having to send the entire light back to the manufacturer each time it misbehaves (pardon if I make any inaccurate statement here, I don't own a HID light). ( On a semi-related note, how realistic is to be able to get parts for a HID light on a short notice? Is it reasonable to expect that parts for HID lights will continue to be available, and affordable, for at least several years going forward? ) Thanks!

 

[tbone1004]

which lights failed? Remember that LED's have life reduction when they are overdriven, and if the manufacturer used questionable electronics it is made even worse. HID's are a lot better now with the automotive bulbs and what not vs. the old medical style, but the tradeoff in drop resistance and size of the head is enough for me to not even consider HID. The big heads are just a massive turnoff.

 

[kr2y5]

I'd rather not go into specifics, I don't want to be doing any negative PR... let's just say both top brands, light & power source came as a set, and in both cases, the light output suddenly, unexpectedly, and permanently dropped to what appears to be a fraction of what it was before. I just flipped the switch, as I did dozens of times before, and suddenly, the light output was very dim. One light was out of warranty, I gave up on it, never found out what happened. Another apparently had an "emitter failure" first time it broke (not sure what it is now, but the symptoms are identical). I don't know where those LED emitters come from, whether they all track back to the same factory, and how the quality control works compared to HID bulbs. What percentage of emitters could be prone to manufacturing defects, and to being "overdriven" with the voltage in the normal range? One in a million, or 1:100 ?

 

[tbone1004]

may not be the LED's, may very well be the drivers that failed.... I'm not an LED expert, but I don't think the LED's really dim if they start failing. It is usually the rest of the electronics that can fail. The LED's will burn out if you overdrive them, but most commercial lights out there aren't. All I know is the UWLD lights that I have used blow everything else out of the water, there really isn't any comparison, and I trust them completely, much more than the HID's that I came from

 

[kr2y5]

I'm not an LED expert, but I don't think the LED's really dim if they start failing. It is usually the rest of the electronics that can fail.

Thanks, I didn't realize that. That's odd indeed, and maybe the emitter failure diagnosis I got first time was incorrect. Maybe some of the resident LED experts could chip in and say a few words about the possible failure modes of LED lights (as a system)...

 

[KDAD]

LEDs require a constant current at the rated voltage to operate. Reducing the current dims the light. The driver is supposed to regulate these. Over driving them should burn them out, not cause them to dim. A dimming 'bulb' could be caused by a failing battery source or the driver.

Heat is also the enemy to LEDs. Most are mounted on a heat sink. A dive light may not have a sufficient heat sink as it is assumed that they will be used underwater which should help to dissipate the heat.

Only buy a LED light that has stated manufacturer part and bin information on the emitter so you know what you are actually getting. My two Chinese dive lights are said to have Cree XML-T6 emitters.

 

[seaseadee]

From: https://en.wikipedia.org/wiki/High-intensity_discharge_lamp

Brand new high-intensity discharge lamps make more visible light per unit of electric power consumed than fluorescent and incandescent lamps since a greater proportion of their radiation is visible light in contrast to infrared. However, the lumen output of HID lighting can deteriorate by up to 70% over 10,000 burning hours.

From: https://en.wikipedia.org/wiki/Light-emitting_diode

Solid-state devices such as LEDs are subject to very limited wear and tear if operated at low currents and at low temperatures. Typical lifetimes quoted are 25,000 to 100,000 hours, but heat and current settings can extend or shorten this time significantly.

The difference is in the way the two elements produce the light and that is why LED's are said to be more durable. Also to reiterate what another poster said: the life of the LED can be very much altered by current and temperature.

 

[kr2y5]

Thanks. Could someone please explain in layman's terms what is the nature of a "driver" in a LED light. Meanwhile, here's more context. I have two independent canister batteries, about 6 months old (same as the light). Each gives 12.8V without load, which drops to abut 12.3V while the light is connected, and connecting the light to either of them gives the same very dim output. I would think that the batteries are not the source of the problem. Given that a canister supplies a steady voltage, what else is there in a typical LED light circuitry that can break? At this point, I'm just asking to become better educated... the light is obviously going back to where it came from, but I'd like to at least understand what is it that can break. As for the heat or voltage, that should not be an issue, the lights were only ever used in our year-round constant-50F water temps.

 

[KDAD]

Thanks. Could someone please explain in layman's terms what is the nature of a "driver" in a LED light.

An LED requires 3.7 VDC to illuminate. That same LED emitter will accept any amount of current sent to it but it is only rated for 1500 mA. Any more may burn it out. Delivering a regulated, constant current at, say, 1000 mA will make the LED shine bright but will not burn it out.

What a driver does is convert whatever the input voltage is to the required 3.7 VDC and also maintain a constant supply current. Without a constant current driver, an unregulated power source will deliver excess current and burn out the LED.

Given that a canister supplies a steady voltage, what else is there in a typical LED light circuitry that can break?.

I don't know much about the design of your light, but if the LED illuminates, then chances are that the emitter(s) is/are fine. The electronics which make up the driver or the batteries would then be the source of the problem. No chance that there is a dimmer control in it?

I will research a bit on the design of canister lights and see if I can dig anything up.

Edit: Try a fast turn off/back on of the light and see if it changes mode. Some of the drivers used to drive the hi output LED that your light uses have a feature where the mode changes from hi to low and even to strobe and SOS. Doesn't mean that is what yours uses but it is worth a shot. Also, is there anything in the manual...the manufacturer doesn't publish their manual on the website.

 

[kr2y5]

Try a fast turn off/back on of the light and see if it changes mode. Some of the drivers used to drive the hi output LED that your light uses have a feature where the mode changes from hi to low and even to strobe and SOS. Doesn't mean that is what yours uses but it is worth a shot. Also, is there anything in the manual...the manufacturer doesn't publish their manual on the website.

Nope, it's not one of those... and I checked light and voltage directly against battery outlets, where switch was no longer involved. So, from what you say, it sounds like if it's not the emitter, then the voltage-reducing circuitry would have to become repeatedly damaged.

Edit: for more context, I've just checked that while the light is powered, it draws a steady 2.9A current from the battery, which sounds in the ballpark of what I'd expect, given the specs. So, the juice is all there, the voltage and current are right, I think, but the lumens ain't coming out of it anymore.