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Everything Dirt Bike
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Lighting thread.
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<blockquote data-quote="cleonard" data-source="post: 141475" data-attributes="member: 21"><p>125 lumens per watt? I don't think so. The current best LED for these applications is the Cree XM-L. Cree actually recently released an upgraded second version called the XM-L2 that is 15% to 20% better and is less expensive. They are sold in different efficiencies called "bins." Most lights are made with the T5 or T6 bin which. I picked up a helmet light and it still has one of the old XM-L's in it. The best commonly available is the next step above which is called U2.</p><p> </p><p>The advertising on LED lights is way optimistic for the most part. A Cree U2 might actually do 125 lumens per watt if down below freezing and only lightly driven. Neither of those apply in your light unless you ride in the winter and the light has a low setting. High power and high temps reduce the lumens per watt.</p><p> </p><p>The other thing is not all the light makes it out the front of the assembled headlight and the power supply that drivers the LED is not 100% efficient. Between the optical and power efficiencies you can lose 20% to 30%. That's how you can start with a LED that does 100 lumens per watt, but only end up with 75 lumens per watt for the entire system.</p><p> </p><p>What does all that mean? Don't believe marketing and all you can never have enough light. Oh and LED's are future.</p><p> </p><p>All lighting seems to suffer from this. My HID vendor claims 3200 lumens. Uh, no. I have a feeling it's more like 2700 and only 2000 or so make it out the front of the headlight.</p><p> </p><p>For comparison a typical halogen car headlight is about 1000 lumens on low and 1500 on high. There is a lot of variability though.</p></blockquote><p></p>
[QUOTE="cleonard, post: 141475, member: 21"] 125 lumens per watt? I don't think so. The current best LED for these applications is the Cree XM-L. Cree actually recently released an upgraded second version called the XM-L2 that is 15% to 20% better and is less expensive. They are sold in different efficiencies called "bins." Most lights are made with the T5 or T6 bin which. I picked up a helmet light and it still has one of the old XM-L's in it. The best commonly available is the next step above which is called U2. The advertising on LED lights is way optimistic for the most part. A Cree U2 might actually do 125 lumens per watt if down below freezing and only lightly driven. Neither of those apply in your light unless you ride in the winter and the light has a low setting. High power and high temps reduce the lumens per watt. The other thing is not all the light makes it out the front of the assembled headlight and the power supply that drivers the LED is not 100% efficient. Between the optical and power efficiencies you can lose 20% to 30%. That's how you can start with a LED that does 100 lumens per watt, but only end up with 75 lumens per watt for the entire system. What does all that mean? Don't believe marketing and all you can never have enough light. Oh and LED's are future. All lighting seems to suffer from this. My HID vendor claims 3200 lumens. Uh, no. I have a feeling it's more like 2700 and only 2000 or so make it out the front of the headlight. For comparison a typical halogen car headlight is about 1000 lumens on low and 1500 on high. There is a lot of variability though. [/QUOTE]
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