LED Car Tail Lights - Page 1
Forum section: electronics / projects

author: ludzinc
author_rank: Unknown
timestamp: March 21, 2021, 10:52:46 am
content: Hi AllAs a part of my mates 'retro-mod' of his 1970's series Valiant, I want to build some LED tail lights for him. Nevermind legality, these probably will be 'show only' use.Only issue is - what LEDs should I use? Have used 'Piranha' type in the past, but that was over 15 years ago, and was wondering if anyone had any suggestions for something more modern. Probably also a good opportunity to make my first Aluminum board.Only constraints is to be able to get them in sensible - hobby level quantities.(Last project here -http://ludzinc.blogspot.com/2014/07/10-years-on.html)Thanks in advance!

author: Mecanix
author_rank: Frequent Contributor
timestamp: March 21, 2021, 12:22:17 pm
content: Those are the LEDs from my tail lights. German make/model car. Can you (someone) ID them?12V, omni, red color, 4P, size: 7.60x7.60mm

author: Mecanix
author_rank: Frequent Contributor
timestamp: March 21, 2021, 12:30:41 pm
content: hmmm interesting :/ Maybe used to be a Cherry car, prop'ed and made in Germany rather. How come we can find those on some CN ecommerce site??https://item.taobao.com/item.htm?id=636266345636

author: rvalente
author_rank: Frequent Contributor
timestamp: March 21, 2021, 02:37:56 pm
content: The standard for color leds are the 3528, cheap and reliable for 3 decades or so...You do not need a MCPCB for heating dissipation.

author: Zero999
author_rank: Super Contributor
timestamp: March 21, 2021, 02:57:15 pm
content: The general advice is don't modify your car's head/rear lights as they might not comply with the local regulations and could invalidate your insurance, putting you at risk of a fine, or worse.Admittedly, I've done it myself, with my old motorcycle. One of the indicators was smashed, including the lamp-holder, so I replaced the bulb with some orange LEDs. It initially failed the MoT, the mandatory annual roadworthiness test, because it increased the flash frequency above the legal level, so I added a resistor in parallel and it passed. Later I replaced both indicators with proper LED turning signal modules, with external resistors in parallel.

author: gnuarm
author_rank: Super Contributor
timestamp: March 21, 2021, 04:21:07 pm
content: I don't understand. I thought you could by LED bulb replacements? Haven't they been available for some time?https://www.google.com/search?q=car+tail+light+bulb+led&ei=63FXYLGLAaKs5NoPmteW6Ao&oq=car+tail+light+bulb+led

author: Benta
author_rank: Super Contributor
timestamp: March 21, 2021, 04:25:36 pm
content: The LEDs in the Mecanix photo look like Vishay TELUX types.

author: cdev
author_rank: Super Contributor
timestamp: March 21, 2021, 04:35:24 pm
content: Those are a good choice. Very bright, very long life. (the two major concerns)

author: Zero999
author_rank: Super Contributor
timestamp: March 21, 2021, 08:04:45 pm
content: Quote from: gnuarm on March 21, 2021, 04:21:07 pmI didn't know about those. In the case of my motorcycle modification, it was over 12 years ago, they didn't exist back then and the lamp-holder was destroyed, so it wouldn't' have been any good. I only soldered the LEDs in there as a temporary fix.As far as the law and insurance is concerned, those might have a different radiation pattern and higher intensity than the old incandescent lamps, so could cause problems. My advice would be check with the local authorities, your insurance company and a mechanic.

author: ajb
author_rank: Super Contributor
timestamp: March 21, 2021, 08:18:45 pm
content: If you're trying to use/reuse a reflector housing, you need a [set of] LEDs that approximates the uniform point source nature of the small filament in an incandescent lamp. Hence all of those retrofit LED lamps that pack a bunch of small LEDs on all sides of a tiny PCB assembly. The challenge with these is achieving the required power density and compactness required for good optical performance with the reflector without causing excessive thermal stress on the LEDs and other components. You can avoid those problems with a physically larger array of LEDs to provide a visually larger light source without the need of a reflector, which makes the thermal design much easier. The challenge with these solutions is achieving the correct visual size and a sufficiently wide and uniform brightness across the viewing field, which may involve significant challenges in the mechanical design--both how you physically position the LEDs in the right places and at the right angles, and how you support them adequately in a hostile temperature and vibration environment.The purpose of a tail light is not just to poop some light out the back of the car in the correct color, it's to reliably provide a sufficiently conspicuous marker of where your vehicle is and how it's moving on the road to other drivers across a wide range of conditions. If it's truly only a show car then sure, you can get away with a lot, but if it's on the road at all then picking out the LEDs is not the first problem, let alone the only one.

author: gnuarm
author_rank: Super Contributor
timestamp: March 21, 2021, 08:25:50 pm
content: Did no one read when he said?Quote

author: langwadt
author_rank: Super Contributor
timestamp: March 21, 2021, 08:27:07 pm
content: Quote from: gnuarm on March 21, 2021, 04:21:07 pmthat you can buy them doesn't nessecarily mean that they are anymore legal that something you make up yourself

author: gnuarm
author_rank: Super Contributor
timestamp: March 21, 2021, 10:13:17 pm
content: Quote from: langwadt on March 21, 2021, 08:27:07 pmAnd who is going to test them to show a violation?

author: Zero999
author_rank: Super Contributor
timestamp: March 21, 2021, 10:24:45 pm
content: Quote from: gnuarm on March 21, 2021, 08:25:50 pmNo, obviously not.Quote from: gnuarm on March 21, 2021, 10:13:17 pmIf you're involved in an accident and the insurance company and accident investigators discover the lights have been modified, it's quite likely the burden of proof will be on the driver.

author: tunk
author_rank: Super Contributor
timestamp: March 21, 2021, 10:26:21 pm
content: And it may fail the (bi-)annual test, e.g. the MOT in the UK.

author: langwadt
author_rank: Super Contributor
timestamp: March 21, 2021, 10:26:36 pm
content: Quote from: gnuarm on March 21, 2021, 10:13:17 pmnoone, but if you don't replace like for like it is probably not strictly legal unless the part has paperwork that says it is an approved replacement

author: cdev
author_rank: Super Contributor
timestamp: March 21, 2021, 10:46:26 pm
content: Quote from: langwadt on March 21, 2021, 10:26:36 pmI was thinking that too. Studies show that A very bright tail light significantly improves your safety.

author: themadhippy
author_rank: Super Contributor
timestamp: March 21, 2021, 10:51:53 pm
content: Quoteand reduces the safety of those behind who are being dazzled by your super bright lights

author: Benta
author_rank: Super Contributor
timestamp: March 21, 2021, 11:04:41 pm
content: Jeez, people, take deep breath, please. Thank You.The OP clearly states that this most likely is for a "show car".Blood pressure down now? Good.

author: langwadt
author_rank: Super Contributor
timestamp: March 21, 2021, 11:53:02 pm
content: Quote from: Benta on March 21, 2021, 11:04:41 pmjust like every car add-on of questionable legality on ebay et. al. is "for off-road use only"

author: floobydust
author_rank: Super Contributor
timestamp: March 22, 2021, 12:15:38 am
content: I made a custom LED brake light because I've been rear ended a few times and luxury cars such as Mercedes, Cadillac, Porsche etc. have tail lights literally twice as bright. SAE lighting standards suck badly, unless you have the privilege of being rich, headlights included.For the center brake light, the original Toyota one is low efficiency piranha LEDs at 2.4W and resistor dropper. I tried two types of LEDs- generic 3W 45mil bead LED's and Cree XPE on M-core PCB, only at 4W now.I did not go nuclear yet with brightness, that would require a CC buck-converter and I haven't had time to design one. I bought one using pos MBI6651 and it burned up on the bench at 1A.The design hassle is getting rid of heat, an 1157 light bulb can dissipate 27W for 400lm, but even 5W with solid-state is difficult.Also the optical engineering, to keep the viewing angle wide, is something that you must include.There are 1,000's of replacement auto LED lamps on eBay and Ali. Almost all are garbage.

author: gnuarm
author_rank: Super Contributor
timestamp: March 22, 2021, 01:12:54 am
content: Quote from: langwadt on March 21, 2021, 11:53:02 pmNot that at all. On ebay they are telling you the item does not meet regulations. In this case the guy it telling you he doesn't need to meet regulations because it's a show car.Is that really hard to understand?

author: ludzinc
author_rank: Unknown
timestamp: March 22, 2021, 09:30:11 am
content: Wow. Caused a bit of a storm there.For the record, intent is to build and test against our laws here in South Australia.If it looks like it will pass, will get it passed by the road authority.If it doesn’t, well, we can have the fancy dot matrix graphics on show days only.Yes, we will reuse the original lenses, but not the reflectors.Thanks to all those who suggested LEDs to try. Will get some Piranhas and see where we land.

author: richard.cs
author_rank: Super Contributor
timestamp: March 22, 2021, 10:01:22 am
content: A few years ago I was looking for retrofit LED brake lights, being especially interested in the ~200 ms win on warning time. At 30 mph that corresponds to the person behind you stopping 2.7 m sooner, easily the difference between no-contact and substantial damage.I bought a few different types and couldn't find anything that wasn't noticeably dimmer even before I got into worrying about emission patterns. At that time they all seemed to be based on clusters of horribly over-stressed through-hole LEDs, things have probably (hopefully) moved on.

author: cdev
author_rank: Super Contributor
timestamp: March 22, 2021, 05:52:54 pm
content: Quote from: ludzinc on March 21, 2021, 10:52:46 amThe Piranha LEDS last a very long time.I have a small board in my central hallway - used as a night light, that has a bunch of green and blue piranha LEDs soldered to it in series. It is running off of a 12v wall wart. Its been on pretty much continuously for >20 years, both here and at my previous apartment. there is no timer, it just stays on, with just a little noticable loss in brightness. Granted its likely running well below rated current, but the green ones still, especially are painfully bright if you look at them directly. The blue ones have dimmed I suspect.

author: emece67
author_rank: Frequent Contributor
timestamp: March 22, 2021, 05:58:06 pm
content: .

author: floobydust
author_rank: Super Contributor
timestamp: March 22, 2021, 07:38:20 pm
content: The LED's package determines power handling, which determines brightness class.Piranha's I replaced in my car's side mirror lamps, three amber ones in series, and one had a bonding wire fail and it cut out when cold. The LED's are usually rated 30mA and Cree CP41B parts 70mA.You can't go high in power with piranha parts because the entire LED is encapsulated in plastic and the 4 pins and die frame don't pull out much heat. It's a bit better than a 5mm LED.I wouldn't use piranha LED's for car tail lights, they don't have the power handling needed.

author: Civilenjuneer
author_rank: Newbie
timestamp: March 24, 2021, 01:56:26 am
content: Quote from: floobydust on March 22, 2021, 07:38:20 pm"Piranha" LED's are perfectly fine for tail lights and turn signals. Many, many vehicles use them and there must be millions out there in use from major manufacturers. The flux capacity of the LED is just a function of how many are needed. For hobbyists, a Piranha LED is going to be much easier to use than something like a SnapLED or a PLCC-2/4 package LED or (especially) something like a Luxeon Rebel or Cree XPE type LED which require considerable care and thought into thermal design.