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Author Topic: 7" LED Head lights  (Read 4043 times)
NewbeeMC9
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« on: January 05, 2010, 08:24:01 PM »

Saw these and they didn't seem to be discussed in recent threads.

http://www.jcwhitney.com/7_Round_LED_Headlight?ID=12;0;200014322+2000+150;0;100012;ProductName;50;0;0;0;2023192;0;0    


Waddyalll think? Huh
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« Reply #1 on: January 05, 2010, 08:40:47 PM »

I think they are 300 each lol.
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Van
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« Reply #2 on: January 05, 2010, 08:53:04 PM »

It doesn't seem to say whether they are DOT approved or for off road use.
These, I have had alot of luck on the harleys and my pick em up's, there are a good variety of H-4 bulbs to satisfy the pallet,if one goes out it can be easily replaced. I also like the price Wink
http://www.jcwhitney.com/SEAL_BEAM_HALOGEN_HEADLAMP_CONVERSION_KIT?ID=12;0;1101002824;0;100002;ProductName;8;0;0;0;2003804;0;0
« Last Edit: January 05, 2010, 08:59:31 PM by van » Logged

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« Reply #3 on: January 05, 2010, 08:56:27 PM »

I am pretty sure these are DOT approved.  They are probably the ones made by Truck-Lite.

They still need to meet DOT specs so optically they probably aren't much better than any other DOT headlight.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #4 on: January 06, 2010, 05:45:46 AM »

I am pretty sure these are DOT approved.  They are probably the ones made by Truck-Lite.


They are, in fact, the Truck-Lite items, based on the listed "manufacturer's part number."  Yes, they are DOT approved.

Quote
They still need to meet DOT specs so optically they probably aren't much better than any other DOT headlight.


Remember the DOT standards are a minimum and can be exceeded.   My bus has E-code headlights that are also DOT approved.  I have not tried these nor seen comparative testing on them so I can not comment on how good they are.

-Sean
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« Reply #5 on: January 06, 2010, 08:43:25 AM »

Remember the DOT standards are a minimum and can be exceeded.   My bus has E-code headlights that are also DOT approved.  I have not tried these nor seen comparative testing on them so I can not comment on how good they are.

I thought Ecode and DOT standards for headlights are standards that are very different from each other and can't coexist?

If an Ecode headlight can meet DOT standards why are folks buying Ecode only lights that are technically illegal?  Are headlight manufacturers only meeting the bare minimum for DOT compliance when DOT headlights could be much better?  Which headlights are you using that meet both DOT and Ecode standards?  I would like to look into buying a set.
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« Reply #6 on: January 06, 2010, 11:16:25 AM »

On the subject of headlights........

What are those tiny  round headlights I have seen on some S&S's and Commercial buses called?

Cliff
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« Reply #7 on: January 06, 2010, 11:41:14 AM »

On the subject of headlights........

What are those tiny  round headlights I have seen on some S&S's and Commercial buses called?

Cliff

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« Reply #8 on: January 06, 2010, 12:07:01 PM »

I thought Ecode and DOT standards for headlights are standards that are very different from each other and can't coexist?

It's not that they can't coexist, just that they typically don't coexist.  Just like the UL standards for Boat Cable and for NM cable are not mutually exclusive, and yet no manufacturer of either type bothers to certify to the other standard.

Most E-code headlights would not meet DOT standards, and vice-versa.  To make a lamp that meets both standards would mean compromising the performance of the lamp to each; the E codes allow a lot more light in some directions than DOT (which is why subjectively they seem better), whereas DOT allows somewhat more light in other directions.  DOT also has a narrower range of allowable color temperature.  So in practice, manufactures concentrate on optimizing the lamps for the markets in which they will be sold, rather than trying to achieve a "compromise" that meets both standards to appeal to a very limited market: manufacturers who can't afford (or don't want) to build different models for US vs. Europe.  In practice, few vehicles fit this category, because so many other standards are also different (we have much stricter crashworthiness and passive restraint standards, instrumentation is usually different between SAE and metric unit markets, etc. etc.).

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If an Ecode headlight can meet DOT standards why are folks buying Ecode only lights that are technically illegal?

See above.  The people buying technically illegal E-code lights are doing so because of a subjective belief that the performance is better (meaning more light to the road).  FWIW, people have been adding "technically illegal" auxilliary lights to their vehicles for years for the same reason, and the reasons for the illegality are the same in both cases: there are objective data to support the assertion that these lights can impair the vision of other drivers on the road, reducing overall safety.

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Are headlight manufacturers only meeting the bare minimum for DOT compliance when DOT headlights could be much better?

Generally, yes.  Just as they generally only meet the bare minimum for compliance in many other measures.  The reason is simple:  the average consumer will not spend more money for a car with the additional performance.  You may remember Lee Iacocca telling congress that he would love dearly to put passive restraints in all Chrysler's cars, but to do so Congress would have to mandate it.  That's because he knew it would add a good chunk to the price of every car, and he'd lose sales to Ford and GM if they were not also made to do it.  It is human nature:  we will pay for tangible things we can see and touch, like more cup holders, a better stereo, or power windows, but we tend not to want to pay for more abstract concepts like safer headlights or restraints.  This trend changes very slowly.

As an example of just how good DOT headlamps can be, check out almost any of the high-end European-brand luxury sedans with stock HID items.  The last time I drove one I could hardly believe how good these are.  But then ask what a replacement unit costs, and be ready for sticker shock; over $1,000 for some models.

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Which headlights are you using that meet both DOT and Ecode standards?  I would like to look into buying a set.

My headlights are the OEM items that came on my bus.  They are an obscure Mercedes part made for Mercedes by Bosch, and they take H4 bulbs (which, in my case, are 24-volt).  The housings have one socket and reflector for the high/low headlamp, and a second socket and reflector for an H3 bulb that is technically a fog lamp, all behind one glass lens assembly.  Because the fog lights on with the low beams show what appear to be four "headlamps" lit when I am driving, I get a lot of people flashing their high-beams at me (most vehicles showing four headlamps on would be dual-high-beam sets).

I'm pretty sure Mercedes will still sell these to you (they must be ordered from Germany), but last time I checked, they were over $500 apiece (so $1,000+ for a pair).  I've broken the glass lenses on both sides (I now have Lexan covers on them for exactly this reason) and just that part alone cost me $165 apiece plus shipping; replacing the reflectors that had some corrosion and pitting would have been more than that, so I took them down to a plating shop and got them triple-chromed instead.

The units are very specific to my coach; I haven't a clue how you would mount them to anything else or trim them out.

-Sean
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« Reply #9 on: January 06, 2010, 12:36:50 PM »

Sean, I thought maybe you had a standard size of headlight, but I guess not.
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« Reply #10 on: January 06, 2010, 02:00:13 PM »

Generally, yes.  Just as they generally only meet the bare minimum for compliance in many other measures.  The reason is simple:  the average consumer will not spend more money for a car with the additional performance.  You may remember Lee Iacocca telling congress that he would love dearly to put passive restraints in all Chrysler's cars, but to do so Congress would have to mandate it.  That's because he knew it would add a good chunk to the price of every car, and he'd lose sales to Ford and GM if they were not also made to do it.  It is human nature:  we will pay for tangible things we can see and touch, like more cup holders, a better stereo, or power windows, but we tend not to want to pay for more abstract concepts like safer headlights or restraints.  This trend changes very slowly.

It's amazing how much this trend has changed since the '60s though - nowadays some manufacturers base their entire philosophy around safety - Volvo have been doing it for years, but Renault for instance now push the safety aspect of their products very, very hard, and have been commercially very successful as a result. Rather than just being a simple 'pass or fail' thing that encourages manufacturers to do the minimum necessary, the European safety regulations are based on 'ratings', which allow customers to compare the safety aspects of competing models side-by-side, and encourages the manufacturers to try their hardest.

It remains absolutely true that legislation (or politics if you prefer) remains a key driver in many aspects of vehicle development - the latest battleground is recyclability, which ironically is leading to more metals and less plastics being used in new models now - arguably a technologically backward step. The auto makers kick and scream every time a new regulation comes into force of course, but amazingly always manage to produce what is required without the dire consequences they predicted. But when the auto makers are powerful enough they can sometimes successfully lobby against the new regulations - making their life easier now, but much harder in the long term as they progressively lose out against overseas manufacturers who's local laws mean they've developed a much better product. And it's not just simple things like seatbelts, tyres and lights - I remember how astonished I was when I discovered my Chevy van only has a single-circuit brakes.

For the record, I used to drive a Lexus LS400, and now have a set of LS400 headlights for my bus. Apart from the voltage difference (which can be dealt with) sourcing a set top-spec car headlights for the bus (fairly cheap on Ebay etc) seemed like the obvious thing to do. You do have to be a bit careful though - for instance, it's increasingly common now for cars with the latest technology headlights to also have mechanisms that turn the headlights as the steering is turned - just like the Citroen DS did all those years ago. I assume this is a consequence of the very-sharply defined beam-pattern these modern lights produce, which might possibly be a problem if they are used in a fixed position on a bus

Jeremy



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« Reply #11 on: January 06, 2010, 03:11:21 PM »

...the latest battleground is recyclability, which ironically is leading to more metals and less plastics being used in new models now - arguably a technologically backward step...

It may be a "technologically" backward step - in that it took technology to bring plastic to the point where it was suitable for automotive use relative to metal - but, metal is an ideal recyclable material as is glass, where more than 90% can be reused (even the rusty parts).  Plastics are still derrived from petrolium waste products from the fuel and solvent refining process.  As people start to pull away from fossil fuels as part of the many energy efficiency mandates (or the movement to electric vehicles), the resource that plastics are based on will also be harder to come by.  There are some plastics that are being derrived from corn or other plant materials, but they are more expensive than petrolium-based plastics and have a faster tendancy to biodegrade (decades vs. centuries).


...I assume this is a consequence of the very-sharply defined beam-pattern these modern lights produce, which might possibly be a problem if they are used in a fixed position on a bus...

With airbag ride-height valves, you are not likely to need the headlight beam leveling on your bus for the exact same reasons you do need it in a car (which does not have air leveling...).  Also, the angle that the beam can diverge on a bus vs. a car is lower due to the wheel base (shorter wheelbased = more beam "bounce" for a given bump) - plus you also have the inertia of the bus working in your favor as you go over bumps (which absorbs more of the high-frequency movement that cases "strobing" on small cars like the Honda S2000).  While ineffective in most automobiles a simple mechanical leveling system for the lights should work fine using morse-cables - you could probably even do it with a properly sized air piston system (sum the front and rear axles with a "T", then take the pressure difference to move a dual-action air piston at the lamps...) but it would have to be well sealed.

-Tim
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« Reply #12 on: January 06, 2010, 04:47:27 PM »

Hi Tim

Re. recycling cars - I wonder how long will it be before a car manufacturer announces the 'revolutionary' introduction of cellulose-based materials for major car parts (the irony being that Trabants and others did this years ago to save on steel usage).

Regarding the headlights, I was refering to side-to-side movement rather than up-and-down, but I agree with what you say. The Lexus lights I have for the bus incorporate an electric motor to move them up-and-down (and I know my current Beemer has the same system), but this is for occasional slow adjustment to compensate for heavy loads in the car rather than to keep them level over every bump.

Jeremy

PS. You will remember my question about the LED lights in my loft; I haven't taken one apart yet to find out whether they have resistors fitted, but I presume they don't as I have now noticed another one starting to fail (one of the three LEDs in the fixture having blown). I cannot really understand the logic of not having resistors even when powered by fairly small batteries - if LEDs without resistors will take as much current as they can, how come they don't rapidly discharge the batteries?

Since all the fixtures I have are wired in parallel, I can presumably a wire single resistor of suitable size into the whole circuit, rather than fitting a separate resistor to each fixture? How should I calculate the value of resistor to use? Thanks in advance!


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« Reply #13 on: January 07, 2010, 12:27:00 PM »

Hi Jeremy,

...I cannot really understand the logic of not having resistors even when powered by fairly small batteries - if LEDs without resistors will take as much current as they can, how come they don't rapidly discharge the batteries...


The battery itself has an equivalent series resistance - this is to say between the chemical potential of a fully charged battery and the output - there is a maximum rate at which the plates and the "charged paste" can convert the stored chemical energy into electrical energy.  This "speed limiter" of sorts acts like an imaginary resistor.


...Since all the fixtures I have are wired in parallel, I can presumably a wire single resistor of suitable size into the whole circuit, rather than fitting a separate resistor to each fixture? How should I calculate the value of resistor to use...


First, it probably isn't going to be that simple - every diode has a slightly different forward voltage due to manufacturing process variations, which include things like:

  • the thickness of the die material
  • the width of the band gap (the thing electrons jump when voltage is applied which gives off light)
  • the area (width/length) of the die (may be differrent due to cutting errors)
  • the uniformity of the master wafer material
  • the quality of the master wafer material and doping agents
  • the consistency from one batch to another in the process (you may have LEDs from several batches even from one manufacturer)

All of these things affect the ammount of voltage required to drive and LED and the current required to output a certain ammount of light.  LEDs are current devices by the way, which need only their required forward voltage to begin conducting (and no more), the current dictates the ammount of electrons jumping the diode gap.  A resistor is a voltage deivce, based on the ammount of voltage for a given resistance, a certain ammount of electrons will be allowed to pass.  In order to control the voltage and current to your circuit, you need to use both types of loads (both an LED and resistor) within a series string.



In case you don't have an electrical or electronics background I'm going to go over some simple yet extremely important information that everyone (not just you) should know before playing with this...

Series Circuit:
Each device in a series "chain" draws the same ammount of current since the device which restricts the current the most will limit what is available to the whole chain.  Using the Water analogy, think of this as "flow rate" you can't add or subtract flow rate from a single device in a series chain without affecting the rest of the "pipe".  If a supply is not providing enough voltage to satisfy the needs of all devices in a series circuit some devices in the chain can get starved for voltage potential (as an example a filament light bulb would appear dim in a series that's under-volted).

Parallel Circuit:
Each device in a parallel "tree" draws the same voltage (since they are attached to the same voltage supply), but because each device is attached to the supply directly, each device gets its own current path and thus can draw as much current as it wants (limited only by the current limit of the entire supply). Using the Water analogy, think of this as pressure - each faucet in your house get the same supply pressure because they are all piped in parallel (to the same source). In this case enough current must be supplied be the power supply or devices that need the most current will be starved (this would appear as one LED in a parallel circuit that is dimmer than the others).


So there's a few issues I have with your no-resistor fixtures:

1) If you have the fixures in a parallel circuit each fixture is supplied the same voltage, but not the same current (a higher current-draw fixture has a direct path to the power supply without regulation).  This is because a single resistor will limit the total current supply for all attached devices, but will not ensure that each device gets the SAME current (so all subsequent devices are allowed to fight for as much current as they want - and it's survival of the fittest there...).

2) If the fixtures themselves don't have any regulation for a series string, there is nothing preventing the individual string from drawing as much current as the least current passing element, so you here again are at the mercy of quality control of the LED manufacturer - you may get a full string of low-forward voltage LEDs which will make the LEDs conduct with a lower voltage so as your power supply voltage rises the LEDs simply conduct more current [see problem number one].


For calculating a series resistor value you need this equation from Ohm's Law "E over I times R":

  E
-----
I * R

E = voltage (in Volts)
I = current (in Amps)
R = resistance (in Ohms)

To find a resistance: R = E / I
To find a voltage: E = I * R
To find a current: I = E / R

Things you will need to know to calculate the resistor value:

  • the voltage you are supplying to the circuit
  • the current you need to restrict the circuit to
  • the forward voltage of the devices you are protecting

First, you take the SUM of the forward voltage of the devices and subtract that from the supply voltage to get an ideal what voltage you are going to drop with the resistor:

Assuming LED Vfwd = 1.5V and using 6 LEDs with a 12Volt supply then for this circuit:

12Vsupply - (1.5Vfwd * 6LEDs) = 3Vrdrop


Second you need to know what the current limit is so check your datasheet!!!  If you don't have a datasheet for your LEDs, for the T1-3/4 type LEDs a good current to limit to is between 10mA (0.01Amps) and 25mA (0.025Amps)


Third, you need to use the Ohm's Law equation to find the resistance, for this example I'll assume we are using a T1-3/4 LED that I'll limit to 15mA (0.015Amps):

R = E / I
R = 3Vrdrop / 0.015Amps
200Ohms = 3Vrdrop / 0.015Amps

If you look at this site, you'll see a list of standard resistor values (refer to the 5% value table).  If the value you calculate does not fall directly on a standard resistance value, pick the next HIGHER resistance value.


Lastly, you need to pick a power for the resistor.  You do this by taking the voltage and the current and multiplying them to get Watts plus an engineering margin:

Watts = ( Volts * Amps ) * 1.2engmargin
0.054Watts = ( 3Vrdrop * 0.015Amps ) * 1.2em

Standard power ratings for axial (through-hole) resistors are:
1/4Watt (0.25), 1/2Watt (0.5), 1Watt, 2Watts, 3Watts, 5Watts, 10Watts...  As with the resistance value itself, if your calculated power value does not fall on one of the standard values, you should pick the next HIGHER power value.  For this example, we are safe with a common 1/4Watt resistor.


With LEDs, due to the manufacuring tolerances, it's hard to get one LED to match another LED by using a single current limiting resistor per LED - so manufacturers use LEDs in a series string of at least three (this is a "magic" number when it comes to odds - with a minimum of three LEDs you are making it more  likely you'll have a low Vfwd LED and a high Vfwd LED in the same string).  This will make each LED in the string use the current limit of the lowest current passing device (which should be a resistor anyway!!) and since LEDs are current driven devices, an equal current through all LEDs should result in a darn-near-matching LED output.

Once you have your LED fixtures (series strings with proper current limiting resistors for the given supply voltage) setup properly, you can take those fixtures and place them in parallel like you have wired - without worrying about one fixture drawing more current than another (each is current limited for the supply voltage, and since they are wired in parallel - each gets exactly the same voltage).  The light output should be the same for all of the fixtures at that point.


The issue with having one resistor that is supposed to regulate all of you fixtures is that you can still have a fatal (to the LEDs) difference in current draw AFTER the limiting resistor.  This is why it is prudent to regulate each series string after splitting off a parallel branch.  Very much like fusing each circuit and load, a 100Amp fuse on your house from the power-pole is not enough to limit the current of each subsequent branch - so each circut gets its own fuse/breaker.


Of course, this does not take your power supply into account, nor does it consider the voltage drop (series resistance) of the wire itself!!!  Remember, the resistor is a voltage drive device so if the wire itself consumes some of the voltage due to excessive-length/ poor-sizing you may have less voltage at the actual fixture so less current will flow to the LEDs making them appear a bit dimmer than a fixture on short/propely-sized wire.  Also, every conection from wire-to-wire and circuit-to-circuit has a resistance - the tighter and cleaner the connection, the lower the resistance - the looser and dirtier/corroded the connection the higher the resistance.  Clean, tight connections on properly-sized/shortest-possible-wire circuits will provide the best supply for the lighting fixtures.


Hope this helps...

-Tim
« Last Edit: January 07, 2010, 01:13:23 PM by Tim Strommen » Logged

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« Reply #14 on: January 08, 2010, 12:56:31 AM »

It occurs to me that LED headlights likely suffer from the same problem that LED traffic lights have...which is that they don't produce enough heat to keep snow from sticking to and obscuring them. Admittedly, only a problem in certain conditions.
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