Car LED Headights - Page 1
Forum section: electronics / beginners

author: munnaz
author_rank: Newbie
timestamp: July 09, 2016, 02:43:49 am
content: Hey guys,I am a newb and am having problems with my car headlights after replacing them with LEDs. When I replaced the H4 halogens with the LEDs an inline relay is not switching when the headlights switch to high beam. Works fine with the halogens. I have purchase resistors for the indicators so they are under load and don't flash fast and am wondering if I need a resistor for the headlights as well (on the high beam line)? I also thinking that they might not even have the high beam side connected as they do not increase in brightness significantly when in high beam mode (any way to check-there is continuity between all three pins on the halogen and none on the leds-resistivity check or something?). Any ideas would be great? CHEERSLink to led lights:http://r.ebay.com/7nHSaEand see pic attached

author: cs.dk
author_rank: Unknown
timestamp: July 09, 2016, 04:31:14 am
content: Your H4 does not get much brighter at high beam, theres only 5W difference. Hence the 55/60W marking. The filament is in another place thougt, thats why you get your high beam.You would have continuity between the ground pin and the two filaments. The voltage drop on the LED lamp is probably too high for a DMM to measure continuity/diode test.There is a note on the ebay site; "- This bulb may be not enough bright for headlight."You can test the bulb with a lab PSU.The pin-out should be like this;Note: Those bulbs won't be road legal here in EU, I don't know about Australia though.

author: Brumby
author_rank: Unknown
timestamp: July 09, 2016, 04:57:27 am
content: The resistors on your blinkers are there for loading up the flasher can so that the flash rate is within required limits (60 - 120 per minute) - but you have noted this already. Headlights don't have a flasher can - so no resistors are required.The main concern is whether the LED H4's will be legal here in Australia. They must perform to acceptable standards, producing sufficient light to illuminate the road adequately. Not much use if they don't work at least as well as the incandescent.Here's a red flag:Quote from: cs.dk on July 09, 2016, 04:31:14 amThen there's also the issue of beam shape. If they result in a beam that doesn't conform to legal requirements, you could find yourself in some hot water.If you have just purchased them from some Chinese online seller, chances are they won't be up to scratch - and you'll be falling foul of the same requirements Europe has. If they haven't an approval in Australia, you would be unwise to use them.As I understand it, this also applies to the blinker globes.Oh, and as for the blinker circuit requiring resistors to maintain an acceptable flash rate - it kinda defeats one reason for using the LEDs - lower power. The resistors are simply a dummy load, dissipating power as heat for no real benefit. The other thing is, too, that if an LED blinker fails with this setup, you won't know about it, because the flash rate won't change much, if at all. The 'old school' arrangement with incandescent globes was designed to let you know by a noticeably different flash rate. The audible ticking is also a requirement.

author: djQUAN
author_rank: Frequent Contributor
timestamp: July 09, 2016, 05:24:18 am
content: I agree. The LED arrangement is so much different from the halogen light source (glowing filament in the middle) so you would be lucky if you even get a decent beam out the front without so much spill and glare to annoy other motorists.There are cars that have busted bulb detectors in the headlamp circuit. In Toyotas that I have here, the high beam indicator in the dash does not light up if there is no sufficient load on the headlamp plugs. In another car (Also a toyota) the low beam plug stays on even on high beam mode without a high current load. The indicator also stays off. A single bulb in either socket makes it run normal switching the outputs between high and low beam.

author: Brumby
author_rank: Unknown
timestamp: July 09, 2016, 05:31:40 am
content: Quote from: djQUAN on July 09, 2016, 05:24:18 amOK - I wasn't aware of that. I've just stuck with the traditional technology. Maybe a greater load than LED globes offerisrequired.Still doesn't get away from brightness, beam and approval issues though.

author: chris_leyson
author_rank: Super Contributor
timestamp: July 09, 2016, 05:45:36 am
content: Off topic, I've seen BMW drive rear brake lights PMW fashion and I'm thinking WTF and you couldn't put a capacitor across the lights to smooth out the ripple current. Clueless electronics design but thats BMW engineers

author: LazyJack
author_rank: Frequent Contributor
timestamp: July 09, 2016, 06:01:18 am
content: That is running in pulse mode not for modulating the intensity, there is no need for that on a brakelight. But for getting high intensity, without thermally overstressing the leds. That would not work with smoothed current. BTW the only BMW I've seen this is one of the older 7s, which predated the general availablity of high intensity LEDs.Putting a LED H4 instead of halogen will have an absolutely crap output of light intensity and beam shape and likely to cause glare. The position and the shape of the light emitting surface is very different.In Europe these are illegal, the car would fail roadworthiness test and in most countries police stop these cars and void their roadworthiness on the spot. Thank god, I say, having seen the initial proliferation of the crap Chinese HID and LED bulbs, which were a nightmare to look at. Fortunately they have now mostly disappeared from the roads.

author: chris_leyson
author_rank: Super Contributor
timestamp: July 09, 2016, 06:33:23 am
content: QuoteThey did it on the 7 series, they would dim the brake lights using PWM when the ambient light level dropped, measured with a scope. The PWM screwed up my "brakes on" signal for an after market video to NAV screen interface.

author: djQUAN
author_rank: Frequent Contributor
timestamp: July 09, 2016, 06:44:26 am
content: I've seen many cars PWM the rear LED lights for the tail light function at night and run 100% duty when braking. It is annoying as why can't they use a higher PWM frequency than one which produces obvious flicker.

author: ConKbot
author_rank: Super Contributor
timestamp: July 09, 2016, 07:28:53 am
content: Quote from: djQUAN on July 09, 2016, 06:44:26 amIt's not through incompetence or inability. Peripheral vision is much faster responding then central vision, and is more sensitive to flicker. Ever have a set of cheap led Christmas lights grab your attention due to flicker, but it doesn't look so bad once you're looking at them? A low frequency pwmed tail light will grab the attention of someone better even if they aren't looking directly in that direction. I've also seen a BMW with 'staged' tail lights. On light braking they light up the central portion of the tail lights. On heavy braking the entire tail light lit up and stayed on.In the US at least, the acceptable range of light output from tail lights is pretty wide, so as long as all operating modes are within limits, manufacturers can do stuff like that.Also yes, ditch the led retrofits. No way they could get anywhere near the needed cooling in that form factor. 15w of LEDs would be appropriate in terms of raw lumens, but that leaves 10+ watts to get rid of, with no heat sink. So they are guaranteed to not last long, and definitely not guaranteed to work with your headlight housing to get the correct beam.Just get plain quality bulbs. Not the blue glass "super white" ones. (Blue tip or rear of the bulb is fine, as long as the middle is clear glass ) Sylvania XtraVision if you want something better then plain.Also clean your headlights, as a hazy housing will dull a headlight way worse then you think it is since it happens so slowly.

author: Monittosan
author_rank: Regular Contributor
timestamp: July 09, 2016, 08:00:09 am
content: Indicator Flash rate is a Simple RC circuit in the "flasher can" No need to add load resistors modify the resistor or capacitor value and you will still get the quick flash when the leds die due to over heating

author: jitter
author_rank: Frequent Contributor
timestamp: July 09, 2016, 08:03:54 am
content: Quote from: LazyJack on July 09, 2016, 06:01:18 amAgreed. The headlight units that are made for H4 (or any other type of) halogen lamps were made to have the filament in just the right spot. With "just the right spot", that means there's very very little play. Having the filament only slightly out of alignment (usually with cheap bulbs) means you're causing glare to the oncoming traffic. LEDs won't even come close to emulating a tiny tungsten filament, and that's why retrofit LED bulbs are illegal in Europe to this day, even including the signalling and all rear lights (exempt are license plate lighting bulbs, but only if you mount an allowed colour).Headlight spread pattern is part of the annual roadworthiness test ("MoT" in Britain) and it can make it fail meaning the car is no longer allowed on public roads until it's repaired and retested.For us (EU) it's easy to know if bulbs are sold legally. Look at the base of the lamp and in the brand and type desciption there should be and encircled E (not necessarily round) with a numeral, "E1" in the example below:This indicates this lamp has type approval from a notified body and complies with the ECE-regulations. I assume that other parts of the world use their own regulations and markings, so look for those. On retrofit LED bulbs or rubbish incandescent lamps, they're likely absent. Don't use those. Over here, even very cheap H4 bulbs (costing less than € 2) have approval, but since it's only a type approval, it might mean that regular production batches may not completely comply, so it's safest to use big name branded lamps, even if you have to pay a hefty premium. I've seen those cheap H4 bulbs having a remarkable bend in the glass right above the metal base that can only mean they cause glare... Do yourself and oncoming traffic a favour and use good bulbs.Lamp units themselves also need ECE approval, so as long as a made-for-LED unit complies with the regulations, there's nothing standing in the way for the car manufacturers to use them on new designs in the EU. Retrofit LED bulbs in units made for incandescents are a no no. Some popular cars have aftermarket replacement light units available for them that alter the appearance but do comply with ECE regulations. If those are LED units, then over here that's the only legal way into LED lighting on a car made in the incandescent bulb area. If not, don't do it.

author: fubar.gr
author_rank: Unknown
timestamp: July 09, 2016, 10:11:49 am
content: Quote from: Monittosan on July 09, 2016, 08:00:09 amMost cars use a thermal flasher, where the current sent to the flasher bulbs passes through a bimetallic strip switch.The current warms up the strip and makes it to bend. This breaks the circuit and the strip cools down and current starts passing again, etc.This is why when one or more bulbs are dead, the flasher gets faster. Less resistance equals more current, so the strip warms up faster.See here:http://auto.howstuffworks.com/turn-signal2.htm

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 09, 2016, 10:41:00 am
content: Quote from: fubar.gr on July 09, 2016, 10:11:49 amThat just doesn't sound logical...

author: fubar.gr
author_rank: Unknown
timestamp: July 09, 2016, 10:53:50 am
content: Quote from: PA0PBZ on July 09, 2016, 10:41:00 amYep, you're right it doesn't sound logical. Assuming the bulbs are in parallel, a broken bulb means higher total resistance, therefore less current.But the phenomenon I am describing is true. A broken bulb makes the flasher go faster. I'll try to find a schematic of a bulb flasher.....

author: Augustus
author_rank: Regular Contributor
timestamp: July 09, 2016, 12:22:28 pm
content: Yeah, it's done on purpose to signal the driver there is a bust bulb. But the last bimetallic flasher relays I saw was probably on a 1950 VW Beetle... Today these are all electronic to the point that the typical "relais klicking sound" is done via soundgenerator and speaker in the dashboard

author: Audioguru
author_rank: Super Contributor
timestamp: July 09, 2016, 01:35:57 pm
content: I have noticed on the cars driven in the city at night by idiots who always have the high beams turned on that both the low beam AND the high beam filaments are making lots of light. That explains why a bulb is 55W and 60W, because on high beams it is 115W.I agree that the LED bulbs are made for DRL (daytime running lamps) not for headlights. It is illegal in Canada to tamper with the lighting on vehicles to prevent kids from putting cheap junk ebay lights.

author: cs.dk
author_rank: Unknown
timestamp: July 09, 2016, 02:36:44 pm
content: Quote from: Audioguru on July 09, 2016, 01:35:57 pmNope.With H4 only one of the filaments glow on low/high beam.. It is the filament position that makes the "high beam"..On H1, H7 and others, there is a bulb for both low and high beam. The big defference is, with a H4 you have to choose either low or high. With H1 or H7 the car would usually keep the low beem turned on while using the high beam.

author: Neverther
author_rank: Regular Contributor
timestamp: July 09, 2016, 06:26:59 pm
content: Quote from: cs.dk on July 09, 2016, 02:36:44 pmThis depends on the reference number. On modern cars the maximum combined count for high beams is 100.Headlamps are supposed to have the ref count stamped on the glass.For example, originally both low and high beams are on on my car, I cannot legally add "good" aux highbeams as ref count will go over 100.By removing the relay that switches low beams on on high beams I can now add the aux highbeams.Actually found out that just by cutting out the low beams "improved" the high beams as the eye was not adjusting to the light near the car.You can have both low and high on H4 but usually that just cooks the housing and the silver plating will start flaking.Some people try using 100W and they work for a while untilthe housing cooksAs for led conversions, there arethese onesI've seen some with what looked like SST-90 so I guess they can deliver some power.Not roadlegal, I alredy want to bash headlights on cars with reflector lamps and HID kits. On projector lamps the conversions aren't as bad, but usually they are adjusted wrong.Even original HIDs are bad if they are broken (skoda with broken front sensor could light the roadsigns above the lines on low beams).

author: GEuser
author_rank: Frequent Contributor
timestamp: July 10, 2016, 02:17:10 am
content: One has to be careful with Leds for road use , they come out with different binning and shades (white , cool white , neutral and the likes) and i can verify that colours at night like Rusty brown and slate grey or silver grey can be invisible when illuminated by a led light .Coincidentally for Au , Kangaroos and brown colour animals wont show up in the distance and it might be to late when they do .Also there is a piece of railway line 6ft high vertically placed in the ground just for another example 5m off the side of the road , it was used to support a old power pole which is not there now , that old piece of steel is 150m away LOS from here and using a led light to illuminate that area one would not know that piece of steel was there if one did not already know it was there in the first place , it becomes invisible , using a incandescent it clearly is there ..

author: mikerj
author_rank: Super Contributor
timestamp: July 10, 2016, 07:57:29 pm
content: Quote from: fubar.gr on July 09, 2016, 10:11:49 am20 years or more ago they might still have used bimetallic flasher relays, but they were phased out by electronic flasher relays and cars made in the last 5-10 years tend to have functions like this built into the body control module.

author: LazyJack
author_rank: Frequent Contributor
timestamp: July 11, 2016, 10:39:48 am
content: Quote from: PA0PBZ on July 09, 2016, 10:41:00 amThe bulbs are in _parallel_ with the heating element. Less bulb results in more current in the flasher and thus higher flash speed.

author: jitter
author_rank: Frequent Contributor
timestamp: July 11, 2016, 06:41:16 pm
content: It still doesn't sound logical, unless the flasher circuit were fed by a current source, which I doubt.The last car I owned that had a bimetallic flasher would change the on/off time and frequency when a bulb died, which was way slower than normal, not faster. The indicator bulbs were in parallel with eachother (per side, of course) but in series with the flasher. If one bulb went dead, it would halve the current through the flasher, not double.The only flasher that speeded up the flash frequency with a defect bulb was an electronic one.

author: SeanB
author_rank: Super Contributor
timestamp: July 11, 2016, 06:58:57 pm
content: No matter the vehicle there is a current sensor built into the flasher circuit. either a heater element and the bimetal on older vehicles, or a sense resistor ( a steel part soldered to the board in most modern flashers) or a current sense mosfet on the ones in the instrument panel or body modules.The bimetal will flash slower with a blown bulb, as it senses the hot resistance of the bulb as a potential divider with the element. The others all use the voltage drop across the sense resistor as an input to the flasher control chip to increase the flash rate to a higher rate when it drops below a programmed value. These relays are very tightly controlled in manufacture, you will see them all at around the same frequency with only a very slow beat pattern between the indicators of a line of vehicles waiting to turn for example. A very heavy load also signals to the relay the hazards are on, but it keeps the same flash rate.The integrated flashers simply keep a constant flash rate and warn of blown bulbs via the instrument display, either using a display on a module capable of text or lighting an orange caution lamp, which is invariably ignored by the driver. They also detect shorts and do a brief flash then will set a fail warning. They also have a separate small speaker that does the indicator ticking sound, either with a simple on off pulse or with an actual audio data playback, often using the same speaker for both ticking and other warning chimes.

author: batteksystem
author_rank: Regular Contributor
timestamp: July 14, 2016, 02:27:58 am
content: Quote from: Brumby on July 09, 2016, 04:57:27 amFor headlight in Australia, there is a certain ADR (Australian Design Requirement?) you need to fulfill. I cannot remember which one but would be pretty easy to google I think.

author: gblades
author_rank: Contributor
timestamp: July 14, 2016, 09:49:48 am
content: I would not bother with those bulbs to start with. They will either not be bright enough or if they are they will get too hot and stop working in a fairly short amount of time. They are operating within a confined space with no airflow and little other way to dissipate the heat other than through the wiring. LEDs need to be kept at a much lower temperature than regular bulbs.If you want LED headlight bulbs then you need to get some with decent heat dissipation such ashttp://www.alchemyparts.co.uk/single-super-bright-h4-cree-led-headlight-bulb-hi-low-beam-for-motorbike-motorcycle-trike-quad-scooter/

author: jitter
author_rank: Frequent Contributor
timestamp: July 14, 2016, 04:41:31 pm
content: Don't use them, they're not road legal in the EU. But rather than saying this as it is, Alchemy Parts says: "This light is not E-marked", which implies the exact same thing but sounds a little less compelling.Same thing goes for Australia: in Australia headlights must meetADR46requirements, and this is what the RACQ has to say about aftermarket LED headlight retrofits:Quote

author: djQUAN
author_rank: Frequent Contributor
timestamp: July 14, 2016, 05:15:50 pm
content: Most common LED conversions that have a heatsink use a fan at the back. It's fine at first but what happens when that fails after an engine wash?I have seen several on the road with obvious LED drop-ins which have overheated and the LED phosphor has degraded so the light output turned dim and with a blue tinge to it.I'll stick with my HID projector retrofit, thank you. I also prefer the neutral white 4300K tint.They have neutral white LEDs, I wonder why they don't use them on cars? I would love an off road LED bar with neutral white LEDs

author: VulcanBB18
author_rank: Contributor
timestamp: July 15, 2016, 02:10:51 am
content: Quote from: LazyJack on July 11, 2016, 10:39:48 amI don't think that's quite it...Flasher is in series with the bulbs (& the bulbs are in parallel).When all the bulbs are present, the bimetallic strip heats up quickly (& gets hot), so bends away from the contact post quite a way, then cools and re-contacts (=one flash cycle).When one or more bulbs are blown, the strip doesn't get as hot before it begins to bend and break contact, and because it wasn't as hot it doesn't bend as far away, so returns quicker, thus quick flash!That's how it was explained to me when I was a little tacker anywaycheers,

author: Brumby
author_rank: Unknown
timestamp: July 15, 2016, 04:37:19 am
content: Quote from: VulcanBB18 on July 15, 2016, 02:10:51 amThat's my understanding, too.

author: jakeisprobably
author_rank: Regular Contributor
timestamp: July 15, 2016, 09:07:11 am
content: I wouldn't want LED headlights at all. Look up the CRI index, almost all LED's suck royally. I tried experimenting with quite a few high power LED's in a retail products photo studio. You might as well omit several colors from the spectrum, they don't show up at all. It took me hours tuning Adobe software with a Macbeth color chart before I realized how bad LED CRI can truely be.The same is true with high end road cyclist LED lights. Most cheap lights or stuff older than 2 years is terrible. I've tried almost all of them. The lights are ultra dependent on optical design, and even the better ones are not so good at helping you see certain colors. I don't like missing things visually on a road bike, that's how ya break stuff.The missing parts of the spectrum with bad CRI type LED's are usually the high visibility colors, bright green, orange, flesh tones, they all get messed up. So just what I need... another driver that can't see me on a bike because I look like gray-ish nothing even when I wear "hi-vis" colorsIt's not worth it. I've chat it up with engineers from Niterider, Lezyne, and Light and Motion, it's fairly unanimous that the majority of their design effort goes into the shape of their optics (reflector/lens). If you take the lights apart you will see they are not just a reflector cone and a flat piece of plastic/glass. Putting an LED into a package it's not designed for will have dismal results. Even with a proper design, LED tech is still lacking when it comes to CRI. It's getting better and there are some higher CRI index LED's out there now but they aren't the cheapo stuff.