LED Lights
 

So now that we're into winter, I'm driving with my lights on pretty much my entire commute.

I'm looking into getting some LED bulbs, but I'm trying to debate the cost of purchasing them....I see rear bulbs ranging from $8-$30 dollars, not to mention the special flashers to use LEDs at the proper blink rate. I'm looking at easily breaking $100 to save 100W's. I'm just not sure its worth it.

I thought about maybe building sets of them, but for the time spend doing so and hacking apart a extra set of headlights, the cost is going to be the same ($$$).

I was just wondering if a few other eco-modders can chime in on their experiences. Please include what bulbs you replaced, where you got them, approx. costs, and any +/- feedback about the bulbs.

...if you keep cars for a LONG time, it's probably worth the effort; but if not, then you probably won't recover the co$t inve$tment.

...some of the newer white LEDs are getting MUCH more powerful, almost laser-ligke in output (and current draw, too, of course).

I submit that it would take 25000mi of nighttime driving for each 6.7W #3157 taillight bulb to burn a gallon of gas at 50% alternator efficiency and 25% ICE cycle efficiency.

Will the bulb pay for itself? Eh, maybe a wash if you're lucky.

The big pros and cons of LED taillights for me are the quantity, intensity, and directionality of their light.

I'm trying to figure out how much draw the LEDs actually have on some of these bulbs. its hard because the rating is not given.

A normal 5mm LED is generally 20-30ma. the large 10mm are up to 50ma. So if the "superbrights" are the 50ma type, a 20 LED-bulb goes to 1amp @ 12 volts which is 12 watts...the current 3175 bulbs are 8watts. So some of these could actually be increase electrical consumption!

I'll spill a few more details as to why I'm interested:

My subaru has FOUR 3175 bulbs @ 8W (without braking) plus the two plate lights @ 5W a piece. When I hit the brakes the wattage goes up to 27 on two of the 3175 bulbs. this is not including the third brake light. Quite seriously if I have blinker and and use the brakes (common to slow while turning) the load put on the car is near 100W from brake lights and blinkers. This would include times while sitting at traffic lights. When I'm in traffic in the morning during cold commute this actually causes the low beams to dim and the idle to creep up. Part of the reason I would like to swap to the LEDs as I hit ~10 stops on the commuting path. I probably spending up wards of 8 minutes daily sitting idle with the a 100w load on the alternator at idle.

LEDs drop anywhere between 1.4 Vdc to 4.5 Vdc per LED, depending upon the color and construction. Most red LEDs drop about 1.5 Vdc, though I don't know if this is still true for the super bright ones. So multiple LEDs are often wired in series and share the same current, which saves considerable power. The sum of the voltage drops of all the LEDs in series must be less than the source power, which is about 12 Vdc for most all automobiles, with the difference between the drop across the LEDs and the source power being dropped by a resistor or a regulator circuit.

Good call Sid, I was thinking of a basic one led + resistor circuit for a 12volt automotive application!

A 3v * 0.05ma would only be 0.15 watts, so the 20 LED bulbs would be 3 watts. And those are the dual circuit bulbs which function as brake lights. So the steady on position should be ~half or 1.5W, which is a 6.5 W drop across 4 bulbs. Savings of 26 watts/~2.2amps.

If I swap off the dual 5w plate lights to single led it would go down ~9 watts. Not sure if these would be bright enough, but i have some white LEDS and holders laying around.

The third brake light is a 18w 921 bulb, which I found a 6-3mm Led bulb that is a replacement. 0.020a * 3 volt = 0.06w, @ 6 leds + resistors round 0.5w compared to the 18w currently in place. ~17 watts saved

So looking at 26+9+17 = 52watts or 4.3amps. For the 90amp alt in the Subaru thats ~5% load just from the rear tail lights. Its obviously enough to make the idle change at cold morning runs, so I'm wondering if the minor gains would be worth it?

Not sure if that is worth the bulbs

Found a site that gives the specs on the units:
Third brake light........0.051 amps (x1)...........vs....1.5 amps (x1)
Brake lights..............0.018/0.053 amps (x4) ..vs....0.666/2.25 amps (x4)
Plate Lights..............0.026 (x2) ..................vs....0.416 amps (x2)
Park/Corner Lights.....0.088 (x2) ..................vs....0.666 amps (x2)

Total.......................0.351................. .......vs...6.328

So six amp difference...hmm

6 amp x 12 volt = 72 watts
72 / 745.7 = ~0.10 hp (0.0965)

I'm considering the LED mod just for the sake of being able to do a bit more EOC with lights on and being able to leave my parking lights on while stopped at stop lights without worrying about the drain on my battery. I don't see them being cost effective any other way, but if I can have my engine off for 15 minutes a day (total 1.4-1.5 hour commute time), at .25 gallons per hour, that's a savings of 15 gallons a year... in theory.

While I haven't ordered the car bulbs from deal extreme, I've placed dozens of other orders with them over the last three years on various project builds (LED lights for 24 hour MTB racing). Right now I'm waiting exceedingly long (3 weeks) because international shipping is at a standstill because of the Al Queda package bombing threat, so just be aware before you order. Otherwise, shipping is $0.01 no matter how big or small your order, which probably makes their prices better than anywhere else you'll find.

My big issue is headlights. While HID may offer better performance and a tad bit of energy savings, LED would be the way to go. I'm likely to custom build something at some point because I can easily make a pair of 900 lumen LED lamps that consume 20w vs. 70w+ for a pair of halogens. I'd also have the option of building a low/mid/high beam configuration that could accommodate my needs, whether in city traffic, where I merely need to let my presence be known vs. being able to travel on highways with wildlife. The challenge remains fitting them in a housing that still allows you to bleed excess heat and focus/beam patterning. That's why I need to start with a set of lights from a junkyard, so I can experiment without risk of screwing up my one way of getting to work.

Well I'm not looking at the headlights (not yet). I'm just looking at the standard load from having the lights on. And its not even so much of getting a pay back out of the bulbs. Its more of how much MPG can I get. lol If the 0.1hp gave me .01 gallon less all the time during winter it would be awesome. but I'm pretty sure its much less. But the lights are still something i'm considering. I'm still looking for maybe someone who has more experience with electrical savings on the alternator. Rotational mass is always spinning so its not like I'm going to get a % increase from removing the alt all together. But they respond to electrical load. One which could be a of mild benefit.

The Subaru also has a special little feature (what I consider a mental spasm of a design). The day time running lights are the H1 headlights powered on the low beam @ 35W instead of the 55W. So at night given good conditions I swap down other parking lights and roll with the day time running lights. In well lit locations like in town, highways, traffic, the 20W per side is a waste. So for now I'm not after headlights, just all the other bulbs that I use all the time in the winter months.

If you ran an older diesel, you might want to switch out LEDs and glowplugs for battery efficiency. I'd rip out the stereo and AC if I was going for battery efficiency.

If you have an older bike light run by a dynamo, you could replace the dynamo with a 9V battery and swap the lightbulb for a few LEDs.

Here is your answer!

Don't look for the cost of the LEDs to be paid off in mileage. Look at the cost of the LEDs as a way to prevent getting a ticket for a tail light out since they are more reliable. Then the mileage improvement is icing on the cake.

My LED bulbs were one of the most expensive parts of my project.

I don't expect the current draw of the bulbs alone to make much fuel difference, but since I run w/o an alternator, it takes some stress off of my batteries. When considered a part of the alternator delete, the fuel savings are more apparent.
In particular, my white luxeons in front for driving lights let me leave the headlights off in low visibility but not completely night time conditions (like your winter commute) so it ends up saving 145 watts by not having the headlights on. They don't put as much light on the road, but they are actually more visible to oncoming drivers.

As an extra benefit, the LEDs are all much brighter than the stock bulbs were

i just replaced my interior light with a led from pep boys,

the bulb i took out was a 24 watt,and replaced it with a 1 watt....

the led its much dimmer ,but i can live with it
SO..i did a little math on the savings,

assuming a 2 min run/day for the interior light ,here's the math:
regular bulb

0.8 watts a day
24 watts a month
288 watts an year
2880 wats in ten years

for the led
120 watts for ten years

clearly big savings on the long run
and thats just for one single interiour light
i'm planing to change some more...

The nice thing is we can expect the efficiency of LEDs to go up. LED manufactures make LEDs using obsolete equipment from the computer chip market because they can get it cheap. As the geometries shrink they can increase the efficiency some more. Also look for the price to drop when they get equipment that allows them to go from 6 inch wafers to 12 inch wafers of silicon.

We had a vendor come in with a LED less than 5mm square it was blindingly bright. The demo board had a nice warning sticker on it too.

i hope the price goes down too,

at current prices,about 10 $ per led, the payback is something like 100 years

11,000 wats=1 galon of gas .....approximately

you hit the nail on the head, LED bulbs won't pay you back in mileage. but they will in life span. all of my Jeep's bulbs are LED except the headlights and turn signals, paid about $150 for them all but for the most part i'll never have to change them out ever again. the turns signals aren't worth the money to change since you have to either get an entire new circuit or add a parallel resistor to prevent the fast flash, not worth the extra work. in the first 2 years i owned my jeep i burned out 5 of the 3157 (brakelight/taillight) bulbs, which is about equal to $12.50, as well as several other bulbs, one of which i got a $75 dollar ticket for it being out and me not realizing it.

Electronic turn signal relays work normally with LEDs w/o resistors.
At my local auto shop it was only a couple dollars more than the old style thermal flasher.

LEDs light up instantly, regular tail lights take 0.1 second. At 60mph the extra warning time an LED provides the guy behind you can turn a bad accident into nothing.

If you bulbs have that long of a delay, either they need to be replaced, or you have bad wiring with a high impedance.

I think smokeyj is right... check out LED Lamps on the Drag Racing Tree vs. Incandescent Lamps Tech Article Anaheim Orange County California

I think I am right too.

Here is a link http://deepblue.lib.umich.edu/bitstr...9402600202.pdf

PHD types out of michigan. They actually claim a quarter second to reach 90% light output. Detail their methods etc etc.

Anyway don't take my word, or theirs for it look around! Some cars have mixed technology tail lights 3rd brake lite will be LED and corner lights incandescent.

In these cars you will notice a delay between when the LED lamp comes on and when the incandescent lights come on.

My point was only that while it seems pretty clear that LED lamps won't pay for themselves in saved gas, there is a chance they will pay for themselves in avoided body work and chiropractic

Yes, definitely a noticeable difference between an LED CHMSL and incandescent brake lights... also at traffic lights, where one R,Y,G set is LED and the other is incandescent.

for an ev, any save in power is a good thing.

I still tastefully disagree. If you notice the 1993 article is posted about Lorries, the UK term for Semi-truck. The delay is not caused by the bulbs, its caused by the voltage drop and the slow response from the voltage regulator. Much like if you have a failing alternator on a car, any sudden large consumption of power causes a voltage drop, which is most notable in dimming of lights. LEDs would also be effected in an identical manner, they would only aid in the situation as the voltage drop is less severe due to lower power consumption.

And ditto on the Light Tree. The bulb in the light tree is not a small 3157 with a wire filament thousands of an inch thick. It is a much bigger filament and will take longer to reach full illumination. Also the control relays are being controls from the tower at the dragway, which means a portion of the delay can still be pinned on the design of the system and the length of wire used to control the system. The relays in the system itself probably have variation in response time that is measurable down to the 0.0xx seconds, although these would still plague the LED light system at the end.

Not to mention the incandescent emits enough light from 0.02 seconds to be seen, and they the graph is skewed because I would love to shake the hand the guy who build an LED turn signal that emits a perfectly square impulse, and obviously that circuit lacks any use of a resistor to power adjust the power levels for the LEDs :-)

LED lights light up a significant amount faster
You don't have to take our word for it:

http://www.youtube.com/watch?v=ZPFuwGar-ww

- enough to potentially mean the difference between a rear-end crash or a near miss by a tailgater at highway speeds.

I knew these led lights will save power but spending $100 does not seems to be worth

Ebays got every kind of bulb , bought a pretty bright 3157 I think 60 smd they call it for $4 including shipping , seems good ,so getting the rest same way, saves about 1/2 amp per bulb I figured ,,good thought on the idea of sitting at a light with the engine off, a bit less drain.