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Thanks to Aurabuy for sponsoring this review. 
The UltraFire Cree XM-L T6 is $14.31 shipped. Stock image:
This is a fairly standard flashlight type where the LED's output is collimated by a lens - quite similar to your typical laser pointer. But of course since the emitter area is several orders of magnitude larger, the beam isn't as laser-like. The collimated output from such a configuration projects an image of the emitter itself:
What is unique about this light is that the lens can be adjusted further from the LED, so it can give something of a focal point. Most of the lens-type lights I've played with only adjust between flood, and spot. It is difficult to see here, but the spot size is less than a centimeter.
The lens is a plastic with 23mm diameter and a focal length of about the same. It does not look aspheric in shape. I believe it is a standard plano-convex type.
The body is a nice aluminum, the switch action feels fine, and the focus adjust mechanism is smooth. Unfortunately, there is nothing else I can say about this light that is positive. I'll start by quoting the specs I disagree with.
This is your standard XML die. They do not have that kind of output, and certainly not in this light (see later).
I'm not sure how I would test something that claims to be Shakeproof, short of putting it in a paint mixer. Although that would be hilarious, I don't have access to one, and it would probably shatter the thing.
"Waterproof"? That's easy:
It stayed lit, but water did leak in and fill it up about 10% full. (This was the last test I did, by the way) I has an O-ring on the tail-cap end and one on the front, but the focus mechanism is comprised of several parts, and none of these have a sealing mechanism. Two O-rings total WILL not, and DID not seal all of these parts:
While it does technically have these modes, there is NO regulation. The full battery voltage is passed with a FET into a bank of SMD resistors to limit the current. The modes are created with PWM, so a low battery on "high" will be dimmer than a full battery on "medium." Here is a graph of battery voltage versus current:
There is some strange over-voltage protection thing going on after 4.5V, but only on low mode?? :thinking: Current drops to 30mA. Is that a bug, or is that a feature?
These graph values were measured with a power supply rather than a battery, so it approximates a battery with very low internal resistance (virtually no voltage sag, even with a heavy load). I put a fresh 18650 in there, and current settles around 1.1A. It's about the same for a set of AAAs, oddly enough. I don't see the point of having an XML if you're under-driving it that much.
PWM frequency is 6.2KHz. Here is the voltage waveform across the diode on medium. Duty cycle is about 50%:
And on low. Duty cycle is about 15%:
Driver:
Thermal profile of driver under 2A load after only 30 seconds. I know when it's installed and used with an actual battery it will run cooler, but this is by no means a high performance device:
I'm not exaggerating when I say they've exaggerated this by a million percent. I'd expect about 10 hours tops out of this. Here's why. Remember I said it was focusable? Well with a pointer, the diode remains stationary, and the lens moves. It's the other way around, here. You see these four points on the edge?
That is ALL of the thermal contact to the case. four loosely threaded points. There is a ring of plastic that keeps the LED from falling out. It is not putting pressure on the LED and it is easily removed. When you turn the focus ring, this assembly moves up and down inside the head to adjust the focus:
Hmm. Something's missing here. See if you can spot it:
That's right. No thermal compound of any kind. This LED is sorta flopping around inside it's teeny heat sink and the heat sink doesn't even make proper contact with the case. I wonder how hot it gets? Let's leave it on high for just 20 seconds...
Automatic FAIL
No more testing will be done on this light. It's rusted from the dip in the fish tank anyway.
The driver is terrible, and the heat sinking is the worst I've EVER seen. In order to properly operate an LED, you need to supply it with adequate power, and remove the heat.
This light does neither. 1/10.
Addition: Let this be a warning. A device may look and perform adequately at first, but until you disassemble it and/or actually take some measurements, you will never uncover potentially critical design flaws. Take pointers for example: Beam shots + power graph is NOT enough info for a review.
The UltraFire Cree XM-L T6 is $14.31 shipped. Stock image:
This is a fairly standard flashlight type where the LED's output is collimated by a lens - quite similar to your typical laser pointer. But of course since the emitter area is several orders of magnitude larger, the beam isn't as laser-like. The collimated output from such a configuration projects an image of the emitter itself:
What is unique about this light is that the lens can be adjusted further from the LED, so it can give something of a focal point. Most of the lens-type lights I've played with only adjust between flood, and spot. It is difficult to see here, but the spot size is less than a centimeter.
The lens is a plastic with 23mm diameter and a focal length of about the same. It does not look aspheric in shape. I believe it is a standard plano-convex type.
The body is a nice aluminum, the switch action feels fine, and the focus adjust mechanism is smooth. Unfortunately, there is nothing else I can say about this light that is positive. I'll start by quoting the specs I disagree with.
This is your standard XML die. They do not have that kind of output, and certainly not in this light (see later).
I'm not sure how I would test something that claims to be Shakeproof, short of putting it in a paint mixer. Although that would be hilarious, I don't have access to one, and it would probably shatter the thing.
"Waterproof"? That's easy:
It stayed lit, but water did leak in and fill it up about 10% full. (This was the last test I did, by the way) I has an O-ring on the tail-cap end and one on the front, but the focus mechanism is comprised of several parts, and none of these have a sealing mechanism. Two O-rings total WILL not, and DID not seal all of these parts:
While it does technically have these modes, there is NO regulation. The full battery voltage is passed with a FET into a bank of SMD resistors to limit the current. The modes are created with PWM, so a low battery on "high" will be dimmer than a full battery on "medium." Here is a graph of battery voltage versus current:
There is some strange over-voltage protection thing going on after 4.5V, but only on low mode?? :thinking: Current drops to 30mA. Is that a bug, or is that a feature?
These graph values were measured with a power supply rather than a battery, so it approximates a battery with very low internal resistance (virtually no voltage sag, even with a heavy load). I put a fresh 18650 in there, and current settles around 1.1A. It's about the same for a set of AAAs, oddly enough. I don't see the point of having an XML if you're under-driving it that much.
PWM frequency is 6.2KHz. Here is the voltage waveform across the diode on medium. Duty cycle is about 50%:
And on low. Duty cycle is about 15%:
Driver:
Thermal profile of driver under 2A load after only 30 seconds. I know when it's installed and used with an actual battery it will run cooler, but this is by no means a high performance device:
I'm not exaggerating when I say they've exaggerated this by a million percent. I'd expect about 10 hours tops out of this. Here's why. Remember I said it was focusable? Well with a pointer, the diode remains stationary, and the lens moves. It's the other way around, here. You see these four points on the edge?
That is ALL of the thermal contact to the case. four loosely threaded points. There is a ring of plastic that keeps the LED from falling out. It is not putting pressure on the LED and it is easily removed. When you turn the focus ring, this assembly moves up and down inside the head to adjust the focus:
Hmm. Something's missing here. See if you can spot it:
That's right. No thermal compound of any kind. This LED is sorta flopping around inside it's teeny heat sink and the heat sink doesn't even make proper contact with the case. I wonder how hot it gets? Let's leave it on high for just 20 seconds...
Automatic FAIL
No more testing will be done on this light. It's rusted from the dip in the fish tank anyway.
The driver is terrible, and the heat sinking is the worst I've EVER seen. In order to properly operate an LED, you need to supply it with adequate power, and remove the heat.
This light does neither. 1/10.
Addition: Let this be a warning. A device may look and perform adequately at first, but until you disassemble it and/or actually take some measurements, you will never uncover potentially critical design flaws. Take pointers for example: Beam shots + power graph is NOT enough info for a review.
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