kmossman
Newly Enlightened
Yes! car voltage levels can vary considerably! Please dont assume constant voltage from a Pb based battery, and that includes the vast majority of car batteries while in operaton.
LED Backup Light Upgrade
- Thread starter kuksul08
- Start date
Yes! car voltage levels can vary considerably! Please dont assume constant voltage from a Pb based battery, and that includes the vast majority of car batteries while in operaton.
I like that idea, but I do not feel it is a possible upgrade to existing lights, at least not enough of an upgrade.
Even though LEDs product less heat, they are still more sensitive to that heat than incan bulbs, since increased heat in incan bulbs results in higher resistance, while increased heat in LEDs results in lower, more current, LED permanent degradation, LED immediate light reduction.
If you seriously want to achieve the goal you could compromise somewhere. For example instead of the original bulb base, use a solid aluminum rod for extra mass, instead of the bulb base, bore it out to put an insulator in the middle and a wire in the dead middle for the positive contact.
Unfortunately the reality that remains is that if LEDs were an easy and cost-effective replacement, we'd already have them instead of having to try to DIY.
You simply cannot, the laws of physics prevent it, put a small heatsink on a bulb base that can slide into the same diameter hole an OEM designed for an incan bulb, in the same reflector cavity space, and have equal, let alone more light.
It's why LED lighting is custom made, if we could just reuse incan designs it would be too too easy.
There are other exotic solutions. You could have this drop-in, if you had a duct pumping cold air over it, but then you need a micro compressor or peltier + fan, or again abandon the incan bulb fixture which only serves the purposes of an incan bulb.
I should backpeddle a bit. If you can remove the external lens so you can plug in the "bulb" front behind the car, then you can fit a larger diameter 'sink, but it is a car specific mod, not universal since many cars require trunk access, trunk bulb insertion.
Interesting, but it does beg the question, is the view worth the climb?
Hey guys!
In my car (BMW 3 series), the backup 'light' if that's what they want to call it, is a crappy 21W bulb that barely makes any light. There are two of them. The supply voltage is 12V as would be expected - the multimeter measured about 11.97V.
I want to put an LED in there so that I can actually see things when I back up, and to have something unique. I have already removed the glass bulb from the base, so the interface with the car is good. Since it's pretty much unlimited power, I don't need to bother with a regulated circuit, right? I plan on using a resistor in series.
My question is - what is my best option for LED choice, and optimization of the optics here? The current reflector probably will not work that well for an LED. I am considering an XR-E, or MC-E. I don't have experience with anything else. I am thinking it will be best to do a 2s2p MC-E setup to limit the resistor size needed, but I am open to any ideas.
Here is what I have to work with.
:wave:
Alaric Darconville
Flashlight Enthusiast
Backup lights
I just dropped a pair of those into my Previa. Those bulbs are FANTASTIC!
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Unrelated, but I had to say something
"Raise". "It does raise the question."
I just dropped a pair of those into my Previa. Those bulbs are FANTASTIC!
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Unrelated, but I had to say something
"Raise". "It does raise the question."
kuksul08
Enlightened
Re: Backup lights
Hehe, I get what you're saying. All this work for something I rarely use. IDK, I just wanted something to tinker with.
Did you have the plain old 21W 1156 before? How much different would you say it is?
Hehe, I get what you're saying. All this work for something I rarely use. IDK, I just wanted something to tinker with.
Did you have the plain old 21W 1156 before? How much different would you say it is?
tay
Enlightened
Might want to glance at these guys, they make some PnP bulbs with a single high power emitter and some optics. Supposed to be pretty good. Might be able to take a design cue from them. IMO they have a better heatsink design that relocates the 1156 socket to a pigtail and allows a significant heatsink area outside of the lamp housing.
http://www.elef-usa.com/servlet/the-4/LED-Amber-Signal-Bulb/Detail
I would also say get that 1W resistor out of there and correctly regulate the current for such a high power LED.
Wok
Newly Enlightened
Kuksul08
I replaced each side of my reversing lights with four Cree Q2-WH connected in series, DD.
They are mounted in quad formation on a P4 CPU heatsink,using the Ledil oval optics [from Brum]....the original lamp socket was cutoff and the wires were connected to the loom.
I reverse for about 2 minutes [tricky garage entry]. So far they have been working for over 2yrs.
eng hoe
I replaced each side of my reversing lights with four Cree Q2-WH connected in series, DD.
They are mounted in quad formation on a P4 CPU heatsink,using the Ledil oval optics [from Brum]....the original lamp socket was cutoff and the wires were connected to the loom.
I reverse for about 2 minutes [tricky garage entry]. So far they have been working for over 2yrs.
eng hoe
kuksul08
Enlightened
Thanks, those look pretty crazy. I would spec the 1W resistor for when the car is on, so it would be relatively constant then. It won't matter if it dims once the car is off. I really need to measure the socket with the engine running, but I have heard anywhere from 14 to 14.7 volts.
I decided I will likely run this at 500mA per die actually, to limit heat. Worst case of 14.7V, and 3.3V per die so 14.7-13.2 = 1.5V * .5A = .75W resistor. I might use a 2W to be safe.
Any pictures of your setup?
Diesel_Bomber
Flashlight Enthusiast
- Joined
- Feb 19, 2006
- Messages
- 1,772
I'm sure the individual electronic components have their own regulators if necessary, but automotive bulbs, HVAC blower motors, window motors, etc. just aren't that picky. Hook your DMM up to a power source w/ the car off. Watch the DMM as you start your car.
Most modern cars won't start in reverse anyway, so change in voltage is probably a moot point. However, definitely take voltage readings with the car running. Probably require a second person to safely read the reverse light voltage with the engine running. Either that, or leave yourself a wide safety margin.
How big are your reverse lights? Could you mod them to include one of the LED backup lights listed on this page? They're LED, they're already tested and approved to meet the necessary legal requirements, they already contain all the heat sinking and electrical doodads necessary for proper operation...........
Actually you'd probably see that as all the fun stuff being done for you.
kuksul08
Enlightened
Haha, yes. I am going to stand there and measure the voltage as the car is started, as well as engine revving a bit. Yeah you're right, I am enjoying the challenge and research as much as the end result will be.
Here are a few pics of what it will be going in hopefully.
Here is the socket
The tail light assembly (I already have LED brake and turn signals, but the reverse lights are on the trunk part)
Another view. The red below the reverse light is for European rear fog lights. I could tap into that, but it means a different switch in the cabin.
I would also be interested in these pics! :D
Personally I would use Rebels instead of MC-E. You will need more, but you can pack them tight. The reason for Rebels is they are reliable at high temperatures so less concern about heat sinking IMHO... that or XP-G for efficiency... again to keep the heat to a minimum. I would consider the buck-toot with XP-G.... again, heat.
Semiman
Semiman
Wok
Newly Enlightened
This is my fit....forgot I changed the heatsink :o
http://img695.imageshack.us/img695/2685/reverseled.jpg
Its aluminium channel 50mm x 20mm x 3mm [thick] its about 45mm long to suit my housing. I get about 13v8 @ the wires with engine running.
eng hoe
http://img695.imageshack.us/img695/2685/reverseled.jpg
Its aluminium channel 50mm x 20mm x 3mm [thick] its about 45mm long to suit my housing. I get about 13v8 @ the wires with engine running.
eng hoe
fyrstormer
Banned
I don't know if anyone's pointed this out yet, but if you're reading 11.97v with the engine on, there's something wrong with your alternator or your wiring -- nominal voltage with the engine running is 14v. That could be part of the reason your reverse lights aren't bright enough.
kuksul08
Enlightened
That was with the engine off, and the car had been sitting for about 5 or 6 days actually.
fyrstormer
Banned
Ah. No sense measuring the voltage with the engine off, then; everything on a car is designed to run at 14v, they just put 12v labels on them to keep from confusing the uninformed. On an LED, a difference of +2v can be significant enough to require a design change, in this case in the resistor.
I can certainly understand the appeal of brighter reverse bulbs, and I've been looking for a good solution for a while, but please don't extend it to installing brighter brake lights. The brake lights on some newer cars, especially Toyota SUVs, are so bright that it's literally painful for me to look at them when I'm sitting at a stoplight. I have to close my eyes until the lights get dimmer, meaning the light is green and it's time to go. Even with my eyes closed, my vision is green-tinged for about a minute afterwards.
I can certainly understand the appeal of brighter reverse bulbs, and I've been looking for a good solution for a while, but please don't extend it to installing brighter brake lights. The brake lights on some newer cars, especially Toyota SUVs, are so bright that it's literally painful for me to look at them when I'm sitting at a stoplight. I have to close my eyes until the lights get dimmer, meaning the light is green and it's time to go. Even with my eyes closed, my vision is green-tinged for about a minute afterwards.
kuksul08
Enlightened
I see. It's kind of like how rechargeable AA's are rated at 1.2V but are actually 1.4V off the charger.
I will definitely not mess with my brake lights... if I even could. They are really nice LEDs already and very bright.
fyrstormer
Banned
Yep. Also, alkalines are rated at 1.5v but actually drop to 1.2v almost as soon as you put any load at all on them, and Energizer lithiums are rated at 1.5v but start out at 1.7v. Basically anything designed to run on AAs needs to operate in a range of 1v-2v to be of any use in the real world. Ultrafire batteries get plenty of crap for being cheap, but I have to give them credit for actually specifying the operating voltage range right on the label.
Thanks for promising to leave the brake lights alone. My RX-8's brake lights are LEDs too, and I've sat behind other RX-8s before without discomfort, but I swear Toyota SUVs have brake lights designed to get drivers' attention by making sure they can't see anything else. Ironic, considering Toyotas currently have a runaway-gas-pedal problem, which I imagine leads to more than a few of them tail-ending other people's cars.
Thanks for promising to leave the brake lights alone. My RX-8's brake lights are LEDs too, and I've sat behind other RX-8s before without discomfort, but I swear Toyota SUVs have brake lights designed to get drivers' attention by making sure they can't see anything else. Ironic, considering Toyotas currently have a runaway-gas-pedal problem, which I imagine leads to more than a few of them tail-ending other people's cars.
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kuksul08
Enlightened
Got some parts in:
It looks like the reflector will be too narrow, as some of you suggested. The reflector is much better than the optic as far as containing spill. I think the emitter with no reflector might work.
It looks like the reflector will be too narrow, as some of you suggested. The reflector is much better than the optic as far as containing spill. I think the emitter with no reflector might work.
kuksul08
Enlightened
Got the heatsinks in:
I will also have a custom piece for much added thermal mass.
Question though... Does anyone know what the black insulating material between the positive and negative of the base is made of? Will it damage it if I melt the solder going through the center?
I will also have a custom piece for much added thermal mass.
Question though... Does anyone know what the black insulating material between the positive and negative of the base is made of? Will it damage it if I melt the solder going through the center?
