LED bulbs don't like MSW inverters? - Page 1
Forum section: electronics / general

author: IanB
author_rank: Super Contributor
timestamp: December 04, 2022, 07:00:26 pm
content: I obtained a little Ryobi 150 W inverter with the idea of using it to run a table lamp or two in the event of a power outage. I thought that if an LED bulb uses 7 to 9 W it could run for quite a long time on a 4 Ah battery.However, I've noticed that while these bulbs do indeed draw the rated power from the mains according to my power measuring device (a Kill A Watt clone), they draw twice as much at the input of the inverter, giving an overall efficiency of 50% or less. Since my measuring device doesn't work properly on the output of the inverter, I cannot tell where all the extra power is going. Is it wasted in the bulb, or is it wasted in the inverter?(I am measuring the efficiency by running the inverter off a DC power supply and measuring the input current at a fixed 20 V.)Some LED bulbs don't work at all on the inverter, and I have heard stories of other LED bulbs failing prematurely.For comparison, incandescent bulbs of a similar 6 - 25 W power rating run the inverter at a reasonable efficiency approaching 90%, but this is not helpful when the total power draw is so much higher.I have one 14 W CFL that draws 17 W at the inverter input, and although that's a reasonable efficiency it is still 17 W.Questions:Does anyone know what's the deal with modified sine wave inverters and LED bulbs, and why they don't work efficiently?Does anyone have experience of Kill A Watt devices on MSW outputs, and knows of one that works correctly and gives proper readings?

author: Siwastaja
author_rank: Super Contributor
timestamp: December 04, 2022, 07:36:22 pm
content: How did you actually measure? Did you just measure Pout/Pin and are surprised that the efficiency of the inverter is lower at lower load? That is to be expected because it has some minimum power draw to operate at all, hence efficiency must approach 0% when load power approaches zero. Or did you measure efficiency of incremental power, (Pout2-Pout1)/(Pin2-Pin1), where Pout2>Pout1, or Pout1=0? Even then, the problem might be that the inverter enters some power saving mode at zero output load.

author: IanB
author_rank: Super Contributor
timestamp: December 04, 2022, 09:10:08 pm
content: I attach two graphs. One shows the measured performance with resistive loads (incandescent bulbs), and one with non-resistive loads (various LED and CFL bulbs).The resistive loads show a consistent pattern with an ultimate inverter efficiency of about 92% and a static power consumption of about 2 W.The LED and CFL bulbs show a very inconsistent pattern with an operating efficiency often less than 50%. There is quite a contrast between the two load types.[Edit: I have added the no load point to the first graph]

author: IanB
author_rank: Super Contributor
timestamp: December 05, 2022, 12:21:07 am
content: Quote from: Siwastaja on December 04, 2022, 07:36:22 pmSee my post above. I measured Pout/Pin for various loads, both resistive and otherwise, and looked at the trends. For similar sized resistive and non-resistive loads the efficiencies are markedly different (~80% vs ~50%).

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: December 05, 2022, 06:13:30 am
content: The bulbs that draw more power than expected probably use a capacitive dropper technique. Your inverter is a modified sine wave (yuck) which may be pushing more power through the dropper (and also likely why your AC power meter doesn't like being on the output of the inverter).

author: IanB
author_rank: Super Contributor
timestamp: December 05, 2022, 07:21:20 am
content: Quote from: Geoff-AU on December 05, 2022, 06:13:30 amIt's doubtful they use a capacitive dropper (60 W equivalent bulbs use more sophisticated circuits), but it is true that they are somehow being upset by the modified sine wave. Simple non-dimmable LEDs generally rectify the mains to DC on a reservoir capacitor and then put a current regulator in series with a long string of LEDs so that the regulator only has a small voltage drop across it. For a true sine wave the rectified voltage (V peak) would be about 170 V, but for a modified sine wave it would be lower. The lower peak voltage probably explains why at least one LED bulb fails to light up.For the other bulbs, if they are drawing more current due to the ugly wave form then they are probably running hotter and stressing their internal components, which is not good.I think nearly all consumer level inverters use a modified sine wave. If you browse available products it is nearly impossible to find a pure sine wave output in this space. But this limits the possible loads to purely resistive loads (barely relevant), or to laptop/phone power supplies. Apparently, switched mode power supplies handle a modified sine wave OK.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 05, 2022, 12:43:43 pm
content: Have you considered just using DC LED lamps?

author: tszaboo
author_rank: Super Contributor
timestamp: December 05, 2022, 12:51:32 pm
content: Quote from: IanB on December 05, 2022, 12:21:07 amSo what was the power factor for the LEDs?Or better question, if you have a capacitor on your AC to reduce the voltage (and some linear driver from that) then what happens if your input is a sine wave with a lot of harmonics?

author: IanB
author_rank: Super Contributor
timestamp: December 05, 2022, 02:59:38 pm
content: Quote from: NiHaoMike on December 05, 2022, 12:43:43 pmYes, but USB lamps do not come in the same form factor as mains lamps, so they are not entirely equivalent. Nevertheless, I am exploring this option.

author: IanB
author_rank: Super Contributor
timestamp: December 05, 2022, 03:02:08 pm
content: Quote from: tszaboo on December 05, 2022, 12:51:32 pmThese are commercial, off-the-shelf LED bulbs, either from Philips or from Feit Electric.The power factor for such bulbs is typically around 0.8.I have no way to test for arbitrary mains waveforms.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 06, 2022, 01:33:38 am
content: Quote from: IanB on December 05, 2022, 02:59:38 pmTake a look at 12V LED strips.

author: IanB
author_rank: Super Contributor
timestamp: December 06, 2022, 02:01:07 am
content: Quote from: NiHaoMike on December 06, 2022, 01:33:38 amLED strips are not lamps you can simply place on a table and light up a room.But it does prompt the thought that USB power supplies can negotiate higher voltages than 5 V these days, like 12 V and above, so there should be space for USB powered devices like lamps that can take advantage of this.

author: james_s
author_rank: Super Contributor
timestamp: December 06, 2022, 04:11:46 am
content: It's the dimmable ones that don't like these, the weird waveform confuses the heck out of the dimming circuit. Best case they run dim, worst case they flicker and flash. Smart LED bulbs seem to work fine though, I have a couple of lamps with Hue bulbs that are plugged into modified sine UPS's and they don't even glitch when the UPS kicks in. Many non-dimmable cheap LED bulbs will work fine too.

author: IanB
author_rank: Super Contributor
timestamp: December 06, 2022, 04:18:52 am
content: Quote from: bigfoot22 on December 06, 2022, 04:00:40 amI'm fine with the idea that there are better answers out there, and I agree that it is surely better to keep the 20 V DC from the lithium battery and use it more directly, rather than inverting it up to 120 V AC, only to down-convert it again for an LED light bulb.My question is more of curiosity that the inverter is very inefficient when driving such loads compared to resistive loads. This is not something I've heard anyone talk about, and so I wondered if anyone with an electronics background might have an idea of exactly why this is the case?As far as low voltage solutions are concerned, I will be doing some experiments with USB power and seeing how that works out. I will try to find out how efficient the USB 20 V DC to 5 V DC conversion is compared to the mains inverter. But that will have to wait until I have some USB loads to measure with.I have no problem with Ryobi in general. They make some quite decent tools, and the prices are not so bad if you look out for the special deals and bargains that crop up from time to time. I really like the plug-and-play idea of big lithium batteries and multiple uses that you get from cordless power tools like these.

author: IanB
author_rank: Super Contributor
timestamp: December 06, 2022, 04:24:42 am
content: Quote from: james_s on December 06, 2022, 04:11:46 amI'm trying both dimmable and non-dimmable samples. I just picked up a 9 W (60 W) LED bulb from Dollar Tree for $1.25 (non-dimmable). It measures 7.8 W on the mains, and 20 V, 0.62 A to the inverter, for an effective efficiency of 63%. That puts it top of the efficiency table for all the LED bulbs I have looked at. Next best is the Feit Electric non-dimmable at 55%. The worst is a Philips dimmable bulb at 42%.

author: IanB
author_rank: Super Contributor
timestamp: December 06, 2022, 04:33:41 am
content: It occurs to me that maybe I should include the power factor and apparent power in my table and see how that relates to the effective efficiency.

author: IanB
author_rank: Super Contributor
timestamp: December 06, 2022, 04:38:28 am
content: Quote from: bigfoot22 on December 06, 2022, 04:32:24 amActually, no, I don't think it is. The inverter has a maximum power output of 150 W, and in any case it couldn't do that for very long on a 75 Wh battery.The advertised use cases for the inverter are things like laptops (and maybe only laptops). There's no point plugging in phone chargers when there are USB charging ports already on the inverter, and I struggle to think of any other low power mains devices you might want to power apart from lights.

author: IanB
author_rank: Super Contributor
timestamp: December 06, 2022, 04:44:29 am
content: Quote from: bigfoot22 on December 06, 2022, 04:32:24 amI'll mention again, it is not about the low power, it is about the type of load. The inverter is more efficient driving lower power incandescent bulbs. A 6 W incandescent bulb worked out at 74%, while a 6 W LED bulb managed only 46%.

author: IanB
author_rank: Super Contributor
timestamp: December 06, 2022, 05:36:24 am
content: Quote from: bigfoot22 on December 06, 2022, 04:51:49 amYes, it would be interesting to know whether the additional heat is in the inverter or in the bulb. I don't have an easy way to figure that out (no thermal imaging camera), but I might see if an IR thermometer can help at some point.

author: tszaboo
author_rank: Super Contributor
timestamp: December 06, 2022, 03:15:36 pm
content: Quote from: IanB on December 06, 2022, 04:18:52 amI don't think it's the inverter which is inefficient. Let's make some assumptions. The LED bulb will have a capacitor in series with the phase, a rectifier bridge (probably a smoothing cap) and a constant current driver, and all the LED in series. So in your capacitor, which is sized for 50Hz with zero harmonics will have a certain voltage drop.Let's say 50V.And the linear driver will have a few volt's (3 for the sake of this calculation) of drop. The drop on the capacitor is not a loss, because it's not a "real" current (that's why you have power factor) If you feed it with modified sine wave, with a lot of harmonics, the capacitors voltage drop will be lower, because reactance is less at higher frequency. So the linear driver's voltage drop will increase. Let's say the capacitor will only drop 30V, then suddenly the linear driver will have to dissipate 23V, and your efficiency went down by 50% or so (on 110V mains). Here is a driver like that.https://www.onsemi.com/download/data-sheet/pdf/nsi45015w-d.pdfFigure 14.

author: IanB
author_rank: Super Contributor
timestamp: December 06, 2022, 04:08:00 pm
content: That makes sense. So it's likely the bulb will be running hot inside and may have its life shortened. I might be able to check that by looking at the temperature of the bulb base where the electronics are.

author: james_s
author_rank: Super Contributor
timestamp: December 06, 2022, 06:17:57 pm
content: Quote from: tszaboo on December 06, 2022, 03:15:36 pmIs anybody still making LED bulbs that have a capacitor in series? Every one that I've taken apart has either a small SMPS of some sort or a linear LED driver IC with enough LEDs in series that it doesn't have to drop much.

author: 2N2222A
author_rank: Regular Contributor
timestamp: December 07, 2022, 05:26:43 am
content: Do you have a way of verifying that the amount of light being produced is not greater when used on the square wave inverter power?Do your LED lights have potted control circuits that prevent you from investigating it?Regular 120VAC peaks at 171V, but those inverters peak at 130V to 150V depending on input Voltage and load. Very few have internal voltage regulation. Most adjust the duty cycle of the AC output directly to maintain close to 120VAC RMS.

author: james_s
author_rank: Super Contributor
timestamp: December 07, 2022, 05:28:12 am
content: Quote from: 2N2222A on December 07, 2022, 05:26:43 amIt's trivial to take a relative measurement, a photodiode or small photovoltaic cell and burden resistor connected to a multimeter will make an effective light meter.

author: tszaboo
author_rank: Super Contributor
timestamp: December 07, 2022, 10:27:51 am
content: Quote from: james_s on December 06, 2022, 06:17:57 pmI've seen E14 socketed bulbs that had dropper in them, some 5 years ago. The socket is very small to place any magnetics in them. Of course these come in different shapes and sizes. These were these sort of lamps like below, and they are quite bad to be honest (no smoothing cap in mine, 100Hz blinking and failed bulbs). According to Big Clive, these filaments have 70V forward voltage or so, so the two in series is only 140V. Size dropper cap and linear driver accordingly I guess.

author: james_s
author_rank: Super Contributor
timestamp: December 07, 2022, 06:55:18 pm
content: I thought most of those just had a linear regulator. Whatever the case I find the ones with mains frequency flicker unusable. It's bad on 60Hz and must be awful on 50Hz.

author: tggzzz
author_rank: Super Contributor
timestamp: December 07, 2022, 08:34:31 pm
content: My solution will be to use some LED strip lights, a 12V lead acid battery, and optionally a small DC-DC converter.The ones I have are 4.8W/m at 12V, but at 9V they take maybe 1W without losing much brightness. Cut them to length to get any illumination you want.Examplehttps://uk.rs-online.com/web/p/led-strip-lights/8555933Alternatively buy something like this, but the price is increasing by the week!https://www.wickes.co.uk/Luceco-Compact-USB-Rechargeable-LED-Work-Light/p/233877It has 10hr and 3hr modes too.

author: IanB
author_rank: Super Contributor
timestamp: December 07, 2022, 08:37:39 pm
content: Quote from: bigfoot22 on December 07, 2022, 07:10:10 pmMost of my lights are on dimmers, and I have found that incan bulbs last nearly forever if you soft start them with a dimmer and run them at reduced brightness. I have replaced maybe one bulb among dozens in 20 years of usage.That said, I have been trying out some of the latest generation Philips dimmable bulbs and I like them quite a lot. They have a good CRI and if they flicker at all at 120 Hz it is not something I notice.

author: james_s
author_rank: Super Contributor
timestamp: December 07, 2022, 08:39:45 pm
content: Quote from: bigfoot22 on December 07, 2022, 07:10:10 pmI have lots of LED bulbs that are quite good. 90+ CRI, incandescent like color, no flicker. I really doubt you'd be able to tell me which is which if I put one in a lamp side by side with an incandescent lamp. It's odd to hear somebody preferring CFL, those were a step in the right direction but I've never heard anyone else accuse them of producing good quality light.

author: james_s
author_rank: Super Contributor
timestamp: December 07, 2022, 08:42:42 pm
content: Quote from: IanB on December 07, 2022, 08:37:39 pmIt's pretty trivial to make an ordinary incandescent bulb last tens of thousands of hours if you reduce the voltage. The problem is that the efficiency falls rapidly so it's a false economy. A lower wattage bulb producing the same amount of light would consume a lot less power and the power costs a lot more than the price of a new bulb. Dimmers are very nice for the ambient effect though, and it is certainly convenient to be able to adjust the brightness. Some LED bulbs do mimic the effect of dimming incandescent but none that I've tried got it quite right.

author: IanB
author_rank: Super Contributor
timestamp: December 07, 2022, 08:50:13 pm
content: Quote from: tggzzz on December 07, 2022, 08:34:31 pmWhere I am in USAland the power is quite reliable, so I don't feel I need to make special arrangements as I might if I were in a hurricane zone.I have just been looking for something convenient to give light for 2-3 hours without advance notice or preparation on the rare occasions that the power might go out. So I'm mainly looking at household items that can be re-purposed at an instant's notice, much like candles in a drawer. I figure I will always have a supply of charged lithium batteries on hand especially since their self-discharge rate is so low, and then it would be handy to have simple lights to plug into them.Since mains powered lamps don't seem to be successful, I am looking at USB powered lamps.One curiosity is that the latest USB standards for power delivery allow for 9 V, 12 V, 15 V and higher. So it would be very convenient to have 12 V devices like LED strips that plug into a USB port and negotiate 12 V power delivery. I have not seen any of these yet.I have seen ideas for a USB powered variable voltage power supply, since the latest PD standard allows the voltage to be set in 50 mV increments. You can plug such a power supply into a USB port and get whatever voltage (and current limit) you want on the output terminals. This seems rather cute.

author: IanB
author_rank: Super Contributor
timestamp: December 07, 2022, 08:55:52 pm
content: Quote from: james_s on December 07, 2022, 08:42:42 pmIt's not about economy, it's about light quality. I find full brightness bulbs to be overwhelmingly bright, so I run all the lights in my house at reduced brightness for a more comfortable feel.QuoteI am finding the Philips "warm glow" to be quite acceptable substitutes. They don't go all the way down to dull orange like incans can, but at higher brightness levels I can put them side by side with an incan and the color temperature matches well.

author: IanB
author_rank: Super Contributor
timestamp: December 07, 2022, 08:58:51 pm
content: Quote from: tggzzz on December 07, 2022, 08:34:31 pmI guess the fear of power outages this winter is real, then?

author: tggzzz
author_rank: Super Contributor
timestamp: December 07, 2022, 09:22:07 pm
content: Quote from: IanB on December 07, 2022, 08:37:39 pmI forget whether incandescent bulbs' lifetime goes as v-4or v-6Either way it is irrelevant to the lifetime of LEDs, phosphors, or the components required to run a 3Vdc LED on 240Vac.

author: tggzzz
author_rank: Super Contributor
timestamp: December 07, 2022, 09:26:00 pm
content: Quote from: IanB on December 07, 2022, 08:55:52 pmRunning incandescent bulbs at a lower voltage increases the proportion of inefficient infra red generated.Better to just use a lower wattage bulb.

author: james_s
author_rank: Super Contributor
timestamp: December 07, 2022, 09:28:13 pm
content: Quote from: IanB on December 07, 2022, 08:55:52 pmIf you want less light, why not just use lower wattage bulbs?The Philips Hue variable CCT bulbs have the hardware necessary to go down to 2200k, it's a shame they don't have a dimming mode that does that automatically. It would be nice if it could go even lower CCT but they go as low as any I'm aware of.

author: tggzzz
author_rank: Super Contributor
timestamp: December 07, 2022, 09:30:28 pm
content: Quote from: IanB on December 07, 2022, 08:58:51 pmYup, time to take simple easy precautions.Just as it is in Texas, which is an "electricity island" as a result of choices made because of political dogma.Definitely our enemies in Europe's case (Putin). ISTR Texas governors in the US case.

author: IanB
author_rank: Super Contributor
timestamp: December 07, 2022, 09:41:44 pm
content: Quote from: james_s on December 07, 2022, 09:28:13 pmPartly because now and then I want full brightness for detail work, and partly because I like the warmer light from dimmed bulbs.QuoteI have been trying the regular Philips bulbs (not Hue) which automatically reduce to 2200 K when you dim them. The effect is quite nice.

author: IanB
author_rank: Super Contributor
timestamp: December 08, 2022, 04:47:45 pm
content: Quote from: bigfoot22 on December 08, 2022, 04:39:24 pmI know it's a bit off topic, but I was going to mention in an earlier post that halogens do not take well to dimming. They need to run at full power for the halogen effect to work, or the bulb life may be shortened. So the options are either normal incans or dimmable LEDs. (I don't think dimmable CFLs are very common.)

author: themadhippy
author_rank: Super Contributor
timestamp: December 08, 2022, 05:11:28 pm
content: QuoteTheirs a loophole in the uk for incandescent lamps,they just need to be classed as "rough service" ,not sure how they'd hold up being shipped to Australia,but might be worth a look to see if you have a similar loop hole.

author: IanB
author_rank: Super Contributor
timestamp: December 08, 2022, 05:42:48 pm
content: Quote from: bigfoot22 on December 08, 2022, 04:50:52 pmSure, I have indeed considered that. What happens is the lowest power CFL seems to be a 60 W equivalent with a 13 W power consumption. This works very efficiently on the inverter, but the power consumption is still higher than a 60 W equivalent LED, so it's not quite a win.If I could find a CFL that uses 9 W or so that would be ideal.

author: james_s
author_rank: Super Contributor
timestamp: December 08, 2022, 06:30:38 pm
content: Quote from: IanB on December 08, 2022, 04:47:45 pmThey do ok being dimmed, although the lifespan doesn't increase as much as it does with a standard incandescent because of the halogen effect you mention, but the lower filament temperature reduces evaporation the same way. What they don't like is prolonged operation at very low levels. Stage lighting is mostly halogen and that survives dimming. Those dimmable halogen torchier lamps used to be very popular too, but if you left one on all night very dim the tubular bulb would often be black by the morning.

author: james_s
author_rank: Super Contributor
timestamp: December 08, 2022, 07:53:52 pm
content: Quote from: bigfoot22 on December 08, 2022, 06:46:17 pm9W CFLs are available here too, although CFLs have been getting less and less common in general and I suspect they will be phased out entirely within a few years. My state is banning fluorescent lamps next year which is annoying as fluorescent lamps are still the best blacklights.https://www.amazon.com/Compact-Fluorescent-Spiral-Equivalent-Lumens/dp/B071LK167Y/ref=sr_1_5

author: IanB
author_rank: Super Contributor
timestamp: December 08, 2022, 08:26:30 pm
content: Quote from: bigfoot22 on December 08, 2022, 06:46:17 pmI have tested a Philips 3.5 W bulb (see image attached).It draws 3.6 W on the mains, but 8.6 W through the inverter, making it 42% efficient. It's usable, but I fear for its life.

author: IanB
author_rank: Super Contributor
timestamp: December 08, 2022, 08:30:40 pm
content: Quote from: james_s on December 08, 2022, 07:53:52 pmGah! I just read a news article about California banning fluorescent lamps. I nearly threw up. So much bullshit about saving the world from toxic mercury that is killing people and destroying the planet! Everyone will be so much safer by removing such dangerous articles from circulationWhat about the toxic lead in bullets? How much safer would everyone be if we removed those from circulation?OK, political rant over.

author: IanB
author_rank: Super Contributor
timestamp: December 09, 2022, 10:40:08 pm
content: Quote from: bigfoot22 on December 09, 2022, 07:09:54 pmWhen and if I get round to it

author: IanB
author_rank: Super Contributor
timestamp: December 09, 2022, 10:46:30 pm
content: I have incidentally done some tests with USB lights, and concluded that this particular Ryobi RYi150C device also has a very inefficient USB converterSome numbers may follow when I have time to assemble them.

author: Zero999
author_rank: Super Contributor
timestamp: December 09, 2022, 11:00:07 pm
content: Have you tried 12V LED halogen replacement lamps?https://www.toolstation.com/lighting/mr16/c1416The ones I got for my parents' will work off DC, or high frequency electronic transformers, so a modified sine wave should be no problem.

author: Zero999
author_rank: Super Contributor
timestamp: December 10, 2022, 06:01:02 pm
content: There are loads of warm white, E14 & E27 LED lamps which will work from 12V to 24V.https://www.ledkia.com/uk/buy-bombillas-led-e14-convencional/6423-g45-e14-5w-led-bulb-12-24v.htmlhttps://www.12vmonster.com/collections/12v-24v-led-lamps-and-light-bulbs/products/dc-12v-6w-a19-a60-led-filament-vintage-light-bulb-nostalgic-cage-lamphttps://www.amazon.co.uk/E27-Traditional-Equivalent-450Lumen-warmwhite/dp/B0721JPWWFhttps://bedazzledledlighting.co.uk/product-category/led-bulbs/es-e27/

author: IanB
author_rank: Super Contributor
timestamp: December 10, 2022, 06:51:07 pm
content: Quote from: Zero999 on December 10, 2022, 06:01:02 pmYes, this is something I will check out. I will see what happens if I try to get 12 V from the USB C PD output of the Ryobi RYi150C thing, though from past experience I am not holding out much hope for the conversion efficiency. It had a very poor efficiency when I measured the 5 V USB output driving a 5 V USB lamp. (See below.)The best result so far was the Ryobi USB work light PCL662, with a claimed 800 lumens output for an input of 20 V, 445 mA, 8.9 W, for an apparent 90 lumens/W. The disadvantage of this is the light quality is very harsh and industrial. It's OK if it's the only light you have, but it's not very warm or comfortable.This same PCL662 device also had the best USB conversion efficiency I have seen on its USB output, with an input of 20 V, 294 mA, 5.88 W providing an output of 5.06 V, 980 mA, 4.96 W giving an efficiency of 84%. In contrast, the RYi150C consumed 375 mA for the same output, making the efficiency only 66%.

author: IanB
author_rank: Super Contributor
timestamp: December 11, 2022, 04:46:23 am
content: Yes, my next experiment is going to be a battery adapter that clips on top of a Ryobi battery, a DC-DC converter to produce 12 V output (claimed 95% efficient), and a 12 V LED bulb, something like 60 W equivalent, 800 lumens or so. The bulb itself claims to run off 12-24 V, so I will be interested to see how efficient the bulb is at different voltages.I have to admit I am just playing now, but the experiments are fun, and I will at least have a working solution when I find the best option.It is also amusing to read the review comments on these battery adapters, where people use the 20 V battery to power 12 V or even 6 V motorized toys, and then wonder why things get hot and blow up...

author: IanB
author_rank: Super Contributor
timestamp: December 11, 2022, 04:57:29 am
content: Quote from: bigfoot22 on December 11, 2022, 03:39:33 amBut that's a fishing lure. I would not have expected it to be very bright. You don't want to scare the fish away, you want to attract them

author: james_s
author_rank: Super Contributor
timestamp: December 11, 2022, 07:04:31 am
content: Quote from: IanB on December 11, 2022, 04:57:29 amI have seen projects to build an underwater 175W mercury vapor lamp for attracting fish, I think they're attracted to light the similar to how moths are. The sun is pretty bright.

author: IanB
author_rank: Super Contributor
timestamp: December 11, 2022, 07:21:24 am
content: Quote from: bigfoot22 on December 11, 2022, 06:56:47 amIf you have a USB power bank or two there are loads of USB lights of various brightness available, like for instance this one:https://www.amazon.com/dp/B06XH9XR12It won't light up a whole room, but it is fine as a task light for reading or similar. It uses 90 mA on low, 150 mA on medium and 270 mA on high, so it should give quite a decent run time on a pocket sized USB power bank.

author: IanB
author_rank: Super Contributor
timestamp: December 11, 2022, 07:39:19 am
content: If you want area lighting inside a tent, there is this one:https://www.amazon.com/Onite-20-US24USB3W-WW-Warehouse-Emergency-WarmWhite/dp/B00QX096L0/It is about as bright as a 40 W bulb and if you hang it up high it provides more than enough light for a small space. (It runs at 5 V, 1 A, consistent with the stated 5 W power consumption.)

author: tggzzz
author_rank: Super Contributor
timestamp: December 11, 2022, 09:52:08 am
content: Quote from: IanB on December 11, 2022, 04:46:23 amWhile playing, why not use a standard bench PSU?To measure the relative brightness, measure the photocurrent through a reverse biassed photodiode. The photocurrent will 0.5A/W, and linear over a very wide range.

author: IanB
author_rank: Super Contributor
timestamp: December 11, 2022, 04:52:19 pm
content: Quote from: tggzzz on December 11, 2022, 09:52:08 amThat's how I'm measuring the input to the inverter/converters. I set it to 20 V which is about the average voltage of the 5s battery, and monitor the current.QuoteI have a Mastech MS8229 with a lux meter hiding somewhere. I plan to use that.

author: IanB
author_rank: Super Contributor
timestamp: December 11, 2022, 10:27:22 pm
content: OK, some brightness results. The results are not goodHowever, I have a winner and a much better solution, which I will post about separately.I sampled three bulbs and compared their power consumption and relative brightness between mains power and inverter power:MainsInverterBrightnessPowerBrightnessPowerDollar Tree 60 W (ND)877.9 W9711.1 WFeit Electric 60 W (ND)1308.5 W20016.0 WPhilips 60 W (D)1436.7 W26014.7 WNote: ND = non-dimmable, D = dimmableIt seems clear from this table that the bulbs are being horribly over-driven by the modified sine wave output from the inverter, and they will probably have a very short life if abused this way for any length of time.It is also interesting to note how much more efficient the Philips bulb is compared to the others. All the 60 W bulbs say "800 lumens" on the packaging, but these are clearly legal or marketing lumens, rather than actual lumens.The cheap Dollar Tree bulb seems to survive the inverter best, but it also starts out as the least efficient bulb by some margin.

author: IanB
author_rank: Super Contributor
timestamp: December 11, 2022, 10:45:28 pm
content: Here is the much better solution for off-grid lighting.I found a bulb which has an LED driver built into its base. You can feed it with 12 to 24 V, DC or AC, and it has a relative brightness of 100 on the same scale as my previous post, which puts it smack in the 40 to 60 W bulb equivalent territory and matches its claimed light output of 600 lm. Furthermore it has a pleasant warm white color temperature of 2700 K (my choice) and a 80+ CRI.Power consumption varies from 5.6 W at 12 V DC to 5.2 W at 24 V DC.The outcome of this is you can run it directly from an 18 V tool battery like the Ryobi, with no converters or inverters required, and it can be expected to run for about 12 hours on a 4 Ah battery.Overall, it seems that for many off-grid power applications there is increasingly little point messing about with that 120 V AC stuff. For instance, most laptop power supplies deliver 19 V DC, which is exactly the output voltage of a tool battery.The bulb:https://www.amazon.com/dp/B081DG1L2X

author: tszaboo
author_rank: Super Contributor
timestamp: December 12, 2022, 12:14:15 pm
content: Quote from: IanB on December 07, 2022, 09:41:44 pmI switched almost exclusively to smart lamps at home. Nobody has the time to figure out how much light you need before trying, and it's a guesswork anyway. So I installed Xiaomi and IKEA smart bulbs or lamps with integrated LEDs everywhere, and all of them is controllable with Zigbee or BT remotes. I don't think I ever again want to spend an hour drilling my ceiling and installing a light just to figure it out that the amount of light is bad. And it has like 3 different color temperature settings, and works without an app or internet. Plus, all the bulbs will have some sort of switching drivers, so no chance of blinking. And it's still cheaper than dimmers.

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2022, 06:52:06 am
content: Sounds about right, probably has a simple choke without any PFC cap.

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2022, 06:57:10 am
content: Quote from: bigfoot22 on December 12, 2022, 10:38:10 amIncandescent lamps have a CRI of 100, it's a smooth continuous spectrum just like sunlight, you can't beat the CRI of incandescent with anything else. I'm skeptical of the CCT being anywhere near 4000k CCT unless the bulbs have blue tinted glass. 3200k is a reasonable guess. A 12V lamp is going to be substantially more efficient than a 120V lamp which itself is significantly more efficient than a 240V lamp. A 60W 240V lamp looks pretty close to the brightness of a 40W 120V lamp.

author: IanB
author_rank: Super Contributor
timestamp: December 13, 2022, 07:35:40 am
content: Quote from: james_s on December 13, 2022, 06:57:10 amHave you done a direct side by side comparison with a light meter? Because I come from a 240 V land, and if 240 V bulbs were that lacking in brightness I'm sure I would have noticed it. I don't see any reason for such a difference.

author: IanB
author_rank: Super Contributor
timestamp: December 13, 2022, 07:42:09 am
content: Quote from: james_s on December 13, 2022, 06:57:10 amI can't do it today (it's too late in the evening), but I am going to this experiment (edit: OK, I did it anyway), comparing the light output of a 12 V, 60 W bulb and a 120 V, 60 W bulb with the same input power. I'll post the results here after I have done it. Both bulbs will be the standard A19 bulb shape with frosted glass.

author: IanB
author_rank: Super Contributor
timestamp: December 13, 2022, 08:33:28 am
content: Here's a comparison using bulbs I have on hand. No 240 V bulbs in my collection, sadly.VoltageCurrentPowerBrightnessBulb 112 V4.38 A52 W57Bulb 2108.7 V480 mA52 W67Based on this, I would say the 120 V bulb is ahead. Even though it is dropped in voltage to match the 12 V bulb and thus running cooler, it still has more light output. When running at 120 V, 60 W, the mains bulb has a brightness of 100, which is double the 12 V, 50 W bulb.

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2022, 08:36:28 am
content: Quote from: IanB on December 13, 2022, 07:42:09 amWith a light meter, no, but I have a bunch of 240V bulbs so I can do that. I trust the specs though. It's a bit harder to find specs on incandescent lamps but a 120V 60W lamp is about 800 lumens, what is the 240V version? I can find data on 100W lamps more easily.For example a common 100W 240V GLS bulb is 1320 lmhttp://lamptech.co.uk/Spec%20Sheets/IN%20WC%20GEC%20240-100PS60CL-BC%20Single%20Support.htmA 100W 120V A19 incandescent lamp is 1710lm.https://www.walmart.com/ip/GE-100-Watt-Basic-Light-Bulb-4-Pack-GE-41034-1710-lumen-A19/150144812?wmlspartner=wlpa&selectedSellerId=7675This is a frosted bulb too which has a lumen penalty over a clear one.75W 120V is 1170 lm, nearly as bright as the 100W 240V lamp.https://www.walmart.com/ip/GE-41032-Incandescent-Globe-Soft-White-Bulbs-75-Watts-4-Pack/414640299?athbdg=L1600

author: IanB
author_rank: Super Contributor
timestamp: December 13, 2022, 08:51:04 am
content: Quote from: james_s on December 13, 2022, 08:36:28 amThe quoted lumens seem to vary a lot. I found one example of a 240 V 60 W bulb given as 660 lm. But it's also described as a "rough service" bulb, so the filament may not be optimized for light output. The traditional bulbs were made with a coiled coil filament to keep the heat in and make them run hotter.The trouble is they don't make them anymore, so finding one of the classic bulbs would be a case of finding new old stock.https://www.bltdirect.com/240-volt-60-watt-edison-screw-standard-gls-nbsp-rough-service-pearl

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2022, 06:32:45 pm
content: They're probably crap quality bulbs too, it's hard to find good quality incandescent anymore, most of what is still being made is the cheapest of cheap.

author: IanB
author_rank: Super Contributor
timestamp: December 13, 2022, 06:47:06 pm
content: Yes, of the 12 V bulbs I bought, one had a distorted glass envelope and the other a misplaced filament.I remember many years ago it was possible to get 12 V 60 W bulbs for car inspection lamps that were much higher quality. Unfortunately California seems to have banned them forcing the need to get them from out of state. I'm not sure why 12 V bulbs are banned, it's not like they have any environmental impact.

author: IanB
author_rank: Super Contributor
timestamp: December 13, 2022, 08:35:00 pm
content: So out of curiosity I tried changing the table around and increasing the 12 V bulb power up to 60 W to match the mains bulb. As before, both bulbs are standard A19 shape with frosted glass, measured with exactly the same arrangement and bulb placement.I took care to measure the 12 V bulb voltage at the bulb terminals, since there was about a 0.8 V drop in the wires.VoltageCurrentPowerBrightnessBulb 113.08 V4.69 A61.3 W112Bulb 2121.2 V509 mA61.7 W101Bulb 1 is an Ancor brand 12 V 50 W from West Marine. Bulb 2 is a Sylvania 120 V 60 W Double Life Soft White.It does rather look like the low voltage bulb is doing better here in terms of lumens per watt. On the other hand, it is being over driven compared to spec, so that is probably upping the efficiency a bit.

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2022, 10:33:30 pm
content: It's an interesting test, I'm surprised that the difference is not significantly larger though. Lumens per watt increases with the wattage of the bulb, all else being equal. All else is often not equal though, gas filled bulbs have convective and conductive losses, and conductive losses through the lead wires can be significant too.Regarding the earlier comment, I do think it's odd that anywhere banned 12V incandescent, although I don't see it as being much of an issue really. 12V LED bulbs work very well and are easier to make than line voltage bulbs. Good quality 12V incandescent lamps in other form factors are also widely available such as halogen capsules for automotive and marine use. It would be easy enough to make an adapter for a 55W headlamp or fog light bulb.

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: December 14, 2022, 03:56:33 am
content: Quote from: james_s on December 13, 2022, 10:33:30 pmThis may be because a higher wattage bulb has more LED elements in it, and therefore can be more optimised in terms of burning less energy in the constant current source.In terms of anindividualLED though, Lumens per Watt goes down as you increase the current through the LED and Lumens per Watt also goes down as the LED temperature increases.Vendors don't typically state how they rate a bulb. If they turn it on, measure it, and turn it off again then they'll get a best-case measurement. But if the higher wattage bulb is allowed to heat soak, it will be hotter than a low power bulb, and the efficiency will drop further than the low power bulb will.The amount of heat soak then depends on your lighting fixture, and so on and so onThen you get into the "Double Life" bulbs which are clearly designed to run at a lower temperature and therefore last longer. Lower overall brightness, but better efficiency.There are so many variables that comparing bulbs doesn't make much sense. The only things that matter to an LED are how hot it is and the current density it's running at. The rest of your losses are all overheads from the process of getting the right amount of current to flow through the LED.

author: IanB
author_rank: Super Contributor
timestamp: December 14, 2022, 04:05:53 am
content: Just a note that this thread has gone far from the original topic, and the last several posts have been about incandescent bulbs.Now if someone in Australia has the ability to compare the light output of a 240 V 60 W incandescent bulb with a 120 V 60 W incandescent bulb, that would be very illuminatingThe theory is that the 120 V bulb will have much more light output, but since I do not have any way to lay my hands on a 240 V incandescent bulb, I don't have a way to measure this.

author: IanB
author_rank: Super Contributor
timestamp: December 14, 2022, 04:39:48 am
content: Quote from: bigfoot22 on December 14, 2022, 04:22:45 amI doubt that. But next time I am in the UK I might try to lay my hands on a 240 V bulb to bring back. They are hard to find these days since they have been banned for a long time. It's either a case of NOS, or the special "rough duty" kind that can still be found.

author: james_s
author_rank: Super Contributor
timestamp: December 14, 2022, 07:30:55 am
content: Quote from: Geoff-AU on December 14, 2022, 03:56:33 amI'm talking about incandescent, not LED. With LED bulbs it's typically the other way around, the lower wattage bulbs are more efficient because they don't un the LEDs as hard.With incandescent lamps a higher wattage bulb has a thicker filament and losses from convection and conduction are proportionally lower. The longer and thinner a filament is, the higher these losses are relative to the energy that becomes useful light. It's similar to the reason that one larger engine is usually more efficient than two smaller engines developing the same total power.

author: james_s
author_rank: Super Contributor
timestamp: December 14, 2022, 07:33:31 am
content: Quote from: IanB on December 14, 2022, 04:39:48 amI have a whole box full of British lamps of various types, and I have an AC power source so I can test that when I get around to dragging it out. I have played with it in the past and don't recall there being any visible difference in output from kHz down to around 40Hz when flicker became visible. At 25Hz the flicker is very pronounced.

author: IanB
author_rank: Super Contributor
timestamp: December 14, 2022, 08:03:00 am
content: If anyone is interested, here is the optimal solution I found after my misguided foray into inverters and mains power. There appear to be readily available bulbs that run off a low voltage 12 - 24 V supply, and which have an E26 base to fit into a standard lamp fitting. These bulbs will therefore happily work with the 18 - 21 V supplied by a lithium tool battery, with no inverters or voltage converters required. This also leads to good efficiency and correspondingly economical use of the battery. The light quality is far more pleasant than the light you get from camping lanterns or work lights. In reality of course, you can put the battery on the floor out of sight, and the lamp appears just as if it were plugged into a wall outlet.(It is important, of course, to remember that a low voltage bulb is installed. Some kind of tag on the plug would be indicated as a warning, or even a zip tie to prevent the plug being removed from the connector.)

author: Zero999
author_rank: Super Contributor
timestamp: December 14, 2022, 09:34:23 am
content: Quote from: IanB on December 14, 2022, 08:03:00 amOf just replace the connector, so it can't be plugged into the mains.

author: Zero999
author_rank: Super Contributor
timestamp: December 14, 2022, 12:16:42 pm
content: No, a 12 to 24VDC lamp will not survive 120V to 240VAC. It depends on whether there's space to store the extra lamps. They don't take up much room, so keep them in the loft/attic/basement/garage etc. It's certainly the safer option.

author: IanB
author_rank: Super Contributor
timestamp: December 14, 2022, 05:53:10 pm
content: Quote from: Zero999 on December 14, 2022, 09:34:23 amIn North America, free standing lamps are the most common room lighting solution. In fact, many rooms may have no light fixtures at all (maybe five rooms in my house are like this depending on how you count open plan spaces). So the table lamp or floor standing lamp would be the normal lamp in the room, and during a power outage you would just temporarily replace the bulb and then plug it into a battery.

author: james_s
author_rank: Super Contributor
timestamp: December 14, 2022, 05:53:25 pm
content: I've never seen somebody try it with an LED bulb but I have seen someone accidentally put a 12V RV incandescent bulb into a 120V socket. It was very bright, for a very short period of time, it made a loud pop and the whole inside of the bulb turned black and silver.

author: james_s
author_rank: Super Contributor
timestamp: December 15, 2022, 12:41:53 am
content: Highly doubtful. Resettable fuses are typically quite slow.

author: IanB
author_rank: Super Contributor
timestamp: December 15, 2022, 01:13:48 am
content: Quote from: bigfoot22 on December 15, 2022, 12:23:54 amIf you really wanted to do so, I think you could put something like a bidirectional TVS diode suppressor as a crowbar across the input and then have an inline fuse that blows if the TVS activates. You would have to replace the fuse in this instance, but fuses are cheaper than bulbs.

author: themadhippy
author_rank: Super Contributor
timestamp: December 15, 2022, 01:53:50 am
content: Hate to think how many triacs ive replaced in dimmer packs were they've blown to save the fuse

author: james_s
author_rank: Super Contributor
timestamp: December 15, 2022, 06:52:38 pm
content: Quote from: themadhippy on December 15, 2022, 01:53:50 amUnfortunately it's very difficult for a fuse to protect a semiconductor, they're just not fast enough. The fuse is there to prevent a fire, not to protect the equipment.

author: 2N2222A
author_rank: Regular Contributor
timestamp: December 18, 2022, 06:25:40 pm
content: Quote from: IanB on December 15, 2022, 01:13:48 amIt wouldn't need to be bidirectional since it the 12V light is made to work on DC. But I don't think a TVS diode would work in all cases since it doesn't trip like a varistor. If someone plugged it in to 18 Volts the TVS diode would burn out without drawing enough current to blow the fuse. An SCR that is set to trigger at 18 Volts would work. The SCR datasheet should say what type of fuse (maximum value) is required to protect the SCR.

author: james_s
author_rank: Super Contributor
timestamp: December 18, 2022, 06:34:52 pm
content: Quote from: 2N2222A on December 18, 2022, 06:25:40 pmYou don't necessarily know the polarity it will receive. Most DC sockets have positive on the center button but there is not really a standard as far as I know.

author: IanB
author_rank: Super Contributor
timestamp: December 18, 2022, 07:18:40 pm
content: Bi-directional because the goal is to defend against plugging into the mains. If a TVS cannot sink enough current to blow a fuse before itself being destroyed, then back-to-back SCRs, or a TRIAC?The light itself works on 12 to 24 V AC or DC, so the trip voltage would need to be around 35 V.

author: 2N2222A
author_rank: Regular Contributor
timestamp: December 19, 2022, 07:32:39 pm
content: Quote from: bigfoot22 on December 19, 2022, 12:56:10 amBut for how long? A few miliseconds maximum? If it gets plugged in to a higher Voltage socket that does not supply enough current to blow the fuse, then all the energy has to go through the TVS diode. So it will need a large heat sink. With a thyristor it will trip and short out completely to blow the fuse.QuoteIt's a diode so it will conduct forward biased anyway, which is what it needs to do in a fault condition. No need for back to back TVS diodes. Reverse polarity protection that will save the fuse can be done with a 1N4007 which won't have much loss at 18V+.

author: IanB
author_rank: Super Contributor
timestamp: December 19, 2022, 09:29:55 pm
content: Quote from: 2N2222A on December 19, 2022, 07:32:39 pmThe goal is to save the low voltage bulb if someone plugs the lamp into the mains. This should happen by applying a crowbar as a short circuit across the input, so that the bulb does not experience an excessive voltage. Since the mains has alternating cycles, it is ideal if both polarities of the mains cycle are shorted out, preventing the bulb from seeing even one cycle of high voltage mains. The fuse is going to be something like a 3 amp mains rated fast blow fuse, which when presented with the short circuit from the crowbar should blow almost instantly.

author: Zero999
author_rank: Super Contributor
timestamp: December 20, 2022, 09:28:16 am
content: Quote from: IanB on December 19, 2022, 09:29:55 pmA TRIAC is non-polarised.I doubt a 3A fuse would blow quickly enough to protect the crowbar circuit, unless very high current devices are used.

author: IanB
author_rank: Super Contributor
timestamp: December 20, 2022, 04:39:20 pm
content: Quote from: Zero999 on December 20, 2022, 09:28:16 amInteresting problem. I see that Triacs may have a "Value for fuse" definition: "To protect the device, the I²t rating of the fuse used in series with it must be lower than this specified value."I have not done a parametric search to see what this means in practice with regard to Triac and fuse combinations.https://www.st.com/resource/en/application_note/an2703-parameter-list-for-scrs-triacs-ac-switches-and-diacs-stmicroelectronics.pdf

author: 2N2222A
author_rank: Regular Contributor
timestamp: December 20, 2022, 06:31:56 pm
content: I'm trying to just make the point that a diode can be used to protect the whole thing from reverse polarity, and an SCR can be a crowbar to blow the fuse if it is plugged in to too much Voltage. It's also possible to skip the diode and use a triac. A varistor or TVS diode will catch fire or destroy itself before the fuse blows in some cases. Varistors are mounted beside thermal fuses to prevent fires.

author: IanB
author_rank: Super Contributor
timestamp: December 20, 2022, 06:38:41 pm
content: Yes, but reverse polarity protection is not needed, since the bulb can run on AC.A triac would be fine as a crowbar just as long as it does not blow up to protect the fuse. This is where the maximum I²t rating of the triac comes into play.

author: themadhippy
author_rank: Super Contributor
timestamp: December 20, 2022, 06:56:27 pm
content: Quoteand the I /T of the fuse,maybe use a lower rated fuse than seems sensible,as done by at least one old dimmer manufacturer

author: IanB
author_rank: Super Contributor
timestamp: December 20, 2022, 08:18:43 pm
content: Yes, the bulb uses 300 mA at 18 V, so a 1 A or 500 mA fuse should be fine, maybe even less.

author: 2N2222A
author_rank: Regular Contributor
timestamp: December 21, 2022, 12:39:31 am
content: I didn't realize the LED bulb works on AC. But the SCR crowbar can be put on the output of the rectifier then!

author: IanB
author_rank: Super Contributor
timestamp: December 21, 2022, 12:54:23 am
content: No, no, no, there is no external rectifierThere is a low voltage AC/DC light bulb temporarily installed in a standard table lamp with a mains cord and a mains plug. The risk is that if somebody inadvertently plugged it into the mains, the bulb would blow up, possibly with a bang. Therefore we are considering some kind of black box that could be inserted into the mains cord to protect the bulb in this event.But this idea is flawed, because the installation of the low voltage bulb is meant to be temporary, just used in the event of a power outage. If we went to the trouble of installing a black box in the mains cord, we might just as well cut off the mains plug and install a low voltage connector.So this whole discussion in a sense is a dead end

author: themadhippy
author_rank: Super Contributor
timestamp: December 21, 2022, 02:25:21 am
content: Quoteid be more tempted with a 250mA fuse,

author: vaq
author_rank: Newbie
timestamp: September 06, 2024, 01:46:30 pm
content: I did something similar using an E27 bulb.Ebay item 325422800917 "DC 12V E27 Led Light Bulb 3W 6W 9W 12W 15W 18W 21W 27W 2835 Outdoor Lighting" has a 27 watt warm white if you ask them for it (he will tell you to order the 27W Cold White and will send you the 27W Warm White.)I dare say the CRI is almost as good as most Philips LED bulbs.What's nice about these is they're only LEDs and resistors; 1x 13r per 3 LEDs (9 resistors, 27 LEDs).I shorted each 13r resistor, and use a XL4015 CC/CV buck module to vary it from 0 to 19 watts.I set its current output to limit it to 19 watts (hopefully this LED bulb should last forever.)I replaced its voltage pot with a "3590S-2-103L 10K Ohm Rotary Wirewound Precision Potentiometer Pot 10 Turn" as the brightness control, which only has to be turned ~1 full turn to go from 0 to 19 watts.The buck module is powered by a 12v (4S) lifepo4 battery which stays floated at 13.43v (~92% SOC).At 9.80V the bulb uses ~19 watts and gets up to 87 deg C after 9 minutes (21 deg C ambient, cover taken off bulb, no airflow, used cheap IR temp meter to find hottest spot/s on board.)Running at ~10 watts, got up to 64.6 deg C after 25 minutes.I had to replace the lamp's cheap little switch as it's not designed to switch >1A DCI leave it running all the time. To 'turn it off' I simply turn it down to zero brightness.I put a 4700uF cap across the buck module's output, but it probably wasn't needed.