4 ms·

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

by sudont 15y ago

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.

libria 15y ago
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.
- jcoby 15y ago
  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.
  - LogicHoleFlaw 15y ago
    Those low-hz LED tail lights drive me nuts. The strobing effects are incredibly distracting and headache-inducing.
  - HeyLaughingBoy 15y ago
    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.
- pasbesoin 15y ago
  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.
- djahng 15y ago
  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.
weeny 15y ago
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.
- ianterrell 15y ago
  But then you have a bunch of LEDs to play with in your hardware hacking! Clear win over CFL and incandescent bulbs.
- rektide 15y ago
  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. :)
weeny 15y ago
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.
- wlesieutre 15y ago
  CFL induction lamps might eventually resolve this, but at least for now they're priced out of the general market
  - weeny 15y ago
    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.
SwellJoe 15y ago
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.
- svmegatron 15y ago
  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!
- mahyarm 15y ago
  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.
  - SwellJoe 15y ago
anigbrowl 15y ago
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.
- nitrogen 15y ago
  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.

by sudont 15y ago

libria 15y ago

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.

jcoby 15y ago
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.
- LogicHoleFlaw 15y ago
  Those low-hz LED tail lights drive me nuts. The strobing effects are incredibly distracting and headache-inducing.
- HeyLaughingBoy 15y ago
  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.
pasbesoin 15y ago
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.
djahng 15y ago
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.

weeny 15y ago

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.

ianterrell 15y ago
But then you have a bunch of LEDs to play with in your hardware hacking! Clear win over CFL and incandescent bulbs.
rektide 15y ago
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. :)

weeny 15y ago

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.

wlesieutre 15y ago
CFL induction lamps might eventually resolve this, but at least for now they're priced out of the general market
- weeny 15y ago
  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.

SwellJoe 15y ago

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.

svmegatron 15y ago
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!
mahyarm 15y ago
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.
- SwellJoe 15y ago

anigbrowl 15y ago

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.

nitrogen 15y ago
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.