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Thread: LED flickering

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    Default LED flickering

    So, I'm gradually replacing various lighting items with LEDs. A pair that I put in some months ago has started flickering on startup.

    I'm off-grid with PV, lead-acid batteries, sine-wave inverter, and backup genny.

    The household lighting circuit is DC, nominally 24 volt, but it's an unregulated circuit and it can get up to 30 volts on a sunny day, even 31 volts on an EQ charge (but that hasn't happened lately - a combination of bad weather and aged PV. I have to boost the batteries regularly with the backup genny, but the PV will be upgraded later this year. They're about 20 years old, so I'm not complaining).

    Some months ago I discovered 12-volt bi-pin LED corncobs at Wide World of Lights:


    These aren't the ones I bought, they've updated the range since then, but you get the idea. Many of the fixtures in the house are bi-pin, and previously held 24-volt halogens - boy, those were expensive! So I've got a lot of bi-pin hardware, hence, using bi-pin LEDs. Otherwise, I have to spend more to upgrade the fixtures.

    I've got a 24 volt circuit, so I buy these in pairs, and install them in series. So far, so good. I've put two pairs in the bathroom (2 x 1.5 watt, and 2 x 3.5 watt), and one pair in the kitchen (2 x 3.5 watt). They've been working fine until the last week or so, when the kitchen pair started flickering rapidly on startup. Once they've "warmed up" a bit, the flickering stops.

    Everything on google about LED flicker is talking about dimmer switches and AC circuits. None of that applies here.

    Is there anything I can do to track down the cause? The bathroom LEDs will run cooler, they're on the wall in a half-oyster that has a 1cm gap to the wall, so the airflow is better. The kitchen fixture is ceiling-mounted, with a small gap to the ceiling so air can get out, but there's nowhere for air to get in. Could the LEDs have overheated? Because it uses so little energy, I tend to leave the kitchen light on all day - they don't even register on the PV charge controller's "Load" display. That's compared to an equivalent halogen at 2 - 3 amps.

    I'm happy to replace them, they've already paid for themselves in genny fuel savings, but I'd like to pursue even better lifespan, if it's something I can do, rather than just bad luck with poor quality LEDs. They were about $14-$15 each, so I don't think they're "cheapies".



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    Hmm, interesting.
    My house lights are 12VDC on a standalone battery system charged by micro hydro & solar.

    I have had a lot of problems with LED's flickering also, they work fine for years or sometimes only months, then they turn into strobe lights, first it's intermittent & turning off then on again fixes the flicker, then it becomes permanent & we have a disco strobe going. Wife loves it, not.

    I also think it's due to marginal voltage fluctuations during charge & draining cycles that kills them.

    So I'm very interested in any solutions.

    The best life I've had out of 12V lights is from 12V fluoro lights. But some of them die early too.

    I still toy with the idea of just dumping the 12v lights & going 240v, as I have plenty of power. (Oceanboy, feel like a working holiday?)
    Cheers, Tiny
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    I have discovered that the flickering is the leadfree soldering of the led in their construction if you catch it early you can resolder but its harder to put it back together than putting it in the bin !!
    . Please treat people as you would like to be treated yourself.

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    Thanks, - I don't have the skills to micro-solder, but if the flickering gets too bad, I'll replace them, then pull them apart and see if I can see any bad solder joints. At least I'll know whether it was solder/joint problems or not.

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    Cool flickering

    Quote Originally Posted by Tiny View Post
    Hmm, interesting.
    My house lights are 12VDC on a standalone battery system charged by micro hydro & solar.

    I have had a lot of problems with LED's flickering also, they work fine for years or sometimes only months, then they turn into strobe lights, first it's intermittent & turning off then on again fixes the flicker, then it becomes permanent & we have a disco strobe going. Wife loves it, not.

    I also think it's due to marginal voltage fluctuations during charge & draining cycles that kills them.

    So I'm very interested in any solutions.

    The best life I've had out of 12V lights is from 12V fluoro lights. But some of them die early too.

    I still toy with the idea of just dumping the 12v lights & going 240v, as I have plenty of power. (Oceanboy, feel like a working holiday?)
    By "marginal", do you mean charge/discharge voltage fluctuations? 24 - 30 VDC in my case and sometimes a bit outside those values. Or do you mean the rapid on/off in PWM modes in the charge controller? My plasmatronics apparently has a 200Hz mode to help prolong battery life - something to do with rapid pulsing helps to break down otherwise insoluble lead salt crystals.

    I've also considered converting the whole lighting circuit to 240VAC, but the inverter failed once, and I still had lighting, so there's that ol' "eggs in one basket" thing :-)

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    I have done it out of interest that was my findings , If you pull it apart when it first starts and look at the solder under a usb microscope you can see it as a slightly different grey colour , resolder it and it goes ok , I dont think the supply has anything to do with it as a led dont know which power station generated the power or a battery cheers don
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    Quote Originally Posted by dwywit View Post
    By "marginal", do you mean charge/discharge voltage fluctuations? 24 - 30 VDC in my case and sometimes a bit outside those values.
    Yep that one.
    Cheers, Tiny
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    Quote Originally Posted by dwywit View Post

    I've also considered converting the whole lighting circuit to 240VAC, but the inverter failed once, and I still had lighting, so there's that ol' "eggs in one basket" thing :-)
    Convert to 12V using a step down regulator instead:

    That is just an example to show you what I am talking about, you need to look into what meets your demands.

    I have had 240V LEDS that flicker too, they are just faulty.

    Your 12V LEDs should have regulators inside and if you wire them in series on 24V there is no guarantee that each will get 12V. Due to tolerances or ageing one might get 10V and the other 14V and if you are running 30V things get a lot worse. The internal regulators will keep the brightness to a certain level and then might pulsate when the voltage is outside the working range, but might also go faulty.

    That is why I insist you use a 12V step down regulator for your light circuit and wire them all parallel as intended.
    Last edited by Uncle Fester; 14-05-19 at 11:11 AM.
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    Quote Originally Posted by hinekadon View Post
    I have discovered that the flickering is the leadfree soldering of the led in their construction if you catch it early you can resolder but its harder to put it back together than putting it in the bin !!
    I absolutely hate lead free solder .... bloody greenies !

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    "Convert to 12V using a step down regulator instead:"

    I've given some thought to having such a setup, but the house came with a 24 volt light circuit, 24 volt power circuit (as well as a 240VAC power circuit) - and 24 volt lightbulbs, a 24 volt fridge, and a 24 volt freezer, so I've tended to stay with 24 volts until recently, when 24 volt lightbulbs became ridiculously expensive - when traditional incandescent bulbs reached $10 each I thought "there's got to be a better solution". I started with 24 volt bi-pin halogens - cost was similar, but got better efficiency, which translates to less genny petrol. Then I started putting CFLs in, and then LEDs in pairs of cheaper 12 volt bulbs in series. I spent a lot of money and time replacing bayonet mount fixtures with bi-pin mounts.

    Back to the flicker - it's getting worse, but briefer ? I turned it on this morning (battery voltage was 24.2), and the flicker was worse, but gone after 10 seconds. I'll keep an eye on it. Thanks everyone for your input.

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    just a thought??? to find your flickering try a am transistor radio up close to them ! the ferrite loop will pick up any switching going on and cause interference on the radio but running two in series is not a good idea as you cant get the current difference that occurs with individual diodes and makes them inefficient , cant say theres anything wrong with 24vdc lighting in fact it is preferable over 12v suggest you have a nosey at ebay leds heaps there and cheap china one are ok too with free shipping just gotta wait for them to arrive . the other way is to put a 7812 regulator on each lite and run 12 v lites the 7812 are quite good for a single led only three legs in-earth-out dont need a heatsink and very reliable , I have used them on charterboats that have had volts problems with the corrosion etc no flicker then cheer don
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    Quote Originally Posted by hinekadon View Post
    just a thought??? to find your flickering try a am transistor radio up close to them ! the ferrite loop will pick up any switching going on and cause interference on the radio but running two in series is not a good idea as you cant get the current difference that occurs with individual diodes and makes them inefficient , cant say theres anything wrong with 24vdc lighting in fact it is preferable over 12v suggest you have a nosey at ebay leds heaps there and cheap china one are ok too with free shipping just gotta wait for them to arrive . the other way is to put a 7812 regulator on each lite and run 12 v lites the 7812 are quite good for a single led only three legs in-earth-out dont need a heatsink and very reliable , I have used them on charterboats that have had volts problems with the corrosion etc no flicker then cheer don
    7812 get hot, damn hot and need a sizeable heat sink if using a 10W LED or even the standard 6W downlights that you get cheap at Bunnings or even Aldi sometimes. Ebay LEDs is a hit and miss, more a miss with my experience.

    You can use these little step down modules on each light:

    I recommend to only use exactly this type because they have up to 40V input and the adjuster has 20 turns for accurate setting of 12V and I use them all the time, even on dodgy inductive loads. They are very reliable, which I can not say for any of the other types.
    You can also order them from China for less than 1$ each if you buy 10:

    That is an awesome seller where I can easily lose a $1000 but end up with bucketloads of electronic goodies that I 'really need' but will never find time to use
    This era of thoughtless consumption must end so we can encourage a world of creative geniuses rather than consumer idiots.


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