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Comment by sudont | Hacker News Reader

Does anyone know how they hold up in uneven power situations? As far as I can tell the electronic ballast is the number one reason CFLs fail so frequently, and I've seen plain old incandescents outlast CFLs in many shop conditions.

If LED bulbs actually last the 30 years, they're worth the extra in convenience.

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I live in a motorhome and use LED lighting all over the house. This is, perhaps, the least even power environment I can imagine. They're running off of batteries, which ebb and rise throughout the day based on whether the sun is shining (I have solar panels), I'm plugged into shore power (which causes the battery charger to cycle off and on through the day and night), or I'm driving (the alternator is charging the batteries).

I don't know that they're going to last forever, but I do know my remaining incandescents die about every 6-12 months, and none of the LEDs have burned out. Because LEDs are so expensive ($20 per bulb vs. $1 for the old style) I only use them for the lights I leave on for some length of time, so I still have enough incandescents to make a comparison. So, the LEDs are working harder and not burning out as fast as the incandescents.

I recently bought an LED that has a much more pleasant color than some of the older ones. I don't know exactly what the difference is...they all have yellow tinted covers, but the new one is a more neutral light. Still blueish, but not as harsh. So, I guess they're all getting better at a pretty rapid clip.

I live on a boat and have virtually the same electric/bulb set up. My solar panels also feed a battery bank, and the light bulbs that get used a lot have been switched to LEDs, with the remaining bulbs still incandescent.

A couple of my "soft white" (aka yellowish) LEDs seem to be pretty close in color to incandecents, but a couple have much more of a bluish tint to them. I got an excellent price on the bulbs, so I figure this variance is part of the bargain.

Anyway, high five for living more off the grid!

The low voltage, direct DC environment that you have is far less harsh on electronics than built in AC-DC transformers with much higher voltages, variances and surges. Batteries usually don't peak, their voltage just drops off, which most electronics can deal with just fine. You also have a battery between your electrical system and your solar charger, which smooths things out considerably.

While it's true that batteries act as a nice big filter, the fact is that automotive DC voltage ranges between 9 and 18 volts, depending on what's providing the power, and extremely noisy. I don't know exactly how it all works, but I know when the generator kicks in the lights go from "ok" to "POW! Let's get some lights on in this mofo!"

I'm pretty sure it's a hostile environment...which I'm guessing is why the incandescents die at such an alarming pace. I've had some last as little as a month or two.

The power supply is definitely the critical limiting factor in LED light bulbs. The thing is that to make it rugged for uneven power situations - as you say - you have to use large electrolytic capacitors, which then have a reduced lifetime of their own (and sometimes contain Polychlorinated biphenyls). These limit the lifespan to ~25000 or so hours and burn out while the LED array is still in good shape.

Compared to CFL's, the circuitry is less extreme - LEDs are low voltage devices unlike mercury arcs - and so the driver can definitely last much longer and be more reliable than a comparable CFL ballast.

But then you have a bunch of LEDs to play with in your hardware hacking! Clear win over CFL and incandescent bulbs.

LED & CFL are very much opposite situations for powering: LED uses very low voltage DC at high currents, and CFL uses high frequency high voltage low current. LED's have to be current limited.

I recently picked up a 2V 100A power supply off ebay for some LED projects. :)

another comparison to CFLs. the mercury arc in a CFL is struck between two electrodes, and every time the light is switched on the electrodes degrade. So if you are energy conscious and only have the light on a few hours at a time - you will burn through the CFL much faster. This isn't the case with LEDs - so if you have a light that you use 1 hour a day, you could definitely stretch it out to 30 years.

CFL induction lamps might eventually resolve this, but at least for now they're priced out of the general market

Induction lamps are getting big - but most people want to get rid of the mercury vapor arc entirely and go for solid state, that's a big enough advantage that energy efficiency almost doesn't matter.

Unfortunately, Switch didn't figure out that the light is no longer "solid state" when they added liquid to it - and that a non-toxic liquid is probably worse in many situations than a toxic vapor.

They're good. I've used them on film sets and with dimmers, and they're way easier to work with than fluorescent lights. Also, you don't have that annoying hum from the ballast all the time. If these new bulbs make the grade for domestic lighting then I'll probably put them all over the house.

Film and video have the benefit of being primarily sensitive to specific wavelengths (likely red/green/blue). It seems the problem with LEDs is that certain surfaces are not very reflective in those wavelengths. I have a somewhat similar problem with the CFLs in my kitchen: they put out too much orange light, making things like raw meat, cheese, and orange juice look decidedly odd. I wouldn't be surprised if they look identical to equally-luminous incandescents on camera.

I'm seeing more LED's in automotive use like tail lights, so that's a good sign. Seems like they've nailed down a stable driver that can handle voltage fluctuations, like on starting.

AFAIK, it only takes a zener diode and a resistor to drive LEDs in an automotive application (or any automotive electronic device that runs on < 12V DC). The power is already rectified by the time it leaves the alternator. Worst case is that they're a bit dimmer than normal on startup.

Many car LED tail lights are actually refreshed at (I'm guessing) 30Hz or so to keep from overloading the wire - They have a distinct look to them from the low refresh rate.

While it's certainly possible to do so, I doubt any engineer worth his salt would actually use a zener and resistor as a stable power supply for automotive lighting. Voltage in cars varies from pretty low (sub-8 volts or so) when the starter is cranking, to around 14-16 volts when alternator is running against a fully charged battery, to the occasional high voltage peaks of 40V+ when, e.g., the air conditioner clutch disengages.

That's a pretty large range to run a current-driven device (the LED) from a fixed resistor. Most useful applications these days will use constant-current supplies that feed the LED a fixed amount of current as the input voltage changes all over the place.

Those low-hz LED tail lights drive me nuts. The strobing effects are incredibly distracting and headache-inducing.

Does anyone else find many of these LED tail light designs too bright? I find myself squinting or outright having to look away from them, particularly when immediately behind the vehicle at an intersection.

I've seen a few designs that do not overwhelm in luminosity, but I find most of them to be an outright hazard by partially blinding those in following vehicles.

Voltage fluctuations don't matter since they're driven by a switching constant current supply. The voltage drop across one high brightness LED is only a few volts.

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