Review : Utorch UT02 Flashlight (XHP35 / 26650 / usb rechargeable)(in progress)

Yes but we know how many lumens are produced by a certain wattage according to the data sheets. Efficiency is correlates to the flux bins given. So they all matter equally the same.

When the emitter is placed into a light and fed by a driver the numbers on the data sheet only show best case scenario. So if a light is using a certain number of watts measured at the tail we can assume only that the light is producing less light than data sheet. It cannot produce more.

So… this light is underperforming. Not a big deal, but there is no other way to spin the data. All that said, we need someone to measure the actual light output:)

Not true.
I can be if someone doesn’t understand wat it means and how to use it (not saying you don’t know it btw :wink: ).
:student:
10 Watts = 10 Watts.
10 volt x 1 amp = 10 watt, 1 volt x 10 amp = 10 watt.
If a emitter is doing 100L/W then you’ll get 1000 lumens. (10x100)
It doesn’t matter if the emitter is a xpl or xhp35. Lets assume they are both doing 100L/W.
Xpl: 3 volt x 3.33 amp = 10 watt x 100 lumens = 1000 lumens.
Xhp35: 12 volt x 0.83 amp = 10 watt x 100 lumens = 1000 lumens.

Point is, without knowing and using those other numbers watt doesn’t say a lot. (for example the lumens/watt efficiency)
But with all those numbers it says everything.

In one thing you are completely right, current is what matters to us. It says a lot about how a led performs, but that’s because we know our leds. (meaning we know what to expect and what it can handle)

But we are going off topic :beer:
Sorry about that.

I see people that read spec sheets and don’t build lights.

For example, what do your sheets say about an XHP-35 at 4.5Amps?

What do the spec sheets say about an MT-G2 at 16Amps?

Or an XP-L W2 2B at 6.67Amps?

your wattage per lumen figure is going to vary according to the current you’re pushing, so you don’t have a fixed number to work with. Just like the amperage is going to change as the cell dies, and the forward voltage will fall. All you really have is a voltage reading and current reading, everything else is playing the numbers. And the numbers are not nice. What’s the board temperature? The cell temperature? Where’s the constant? There’s not one.

This makes it easier to pass on this light. :innocent:

Yes, all these things you mention are not constants. They are variables. Variables make up equations that can be calculated. That is all we are trying to do. With the data reported thus far and as I calculated earlier, this light will not reach 1000 lumens. But we will wait to see. Hoping I’m wrong.

Wait… I somehow missed this. So you are getting similar amp draw as the u21 by changing the sense resistor?

Giorgio, could you please downsize the pictures in your review?
Those huge sizes are quite pointless, they’re not even sharp enough for that many pixels.
Thanks.

O uhm… Nice light! Looks good. :+1:
But 1300 LM can be obtained with an XP-L too and then you don’t need a boost driver…

I think the efficacy with an XHP35 is much higher than with an XPL. Secondly, output is also more constant.

Pictures are fine from PC .

I have 4 XHP-35 E4 in my TM16. Each one is seeing 1.14A at some 13.1V making 1768 lumens. Collectively, the 4 are seeing 4.55A in parallel and making 7072 lumens.

Edit: The above said for the statisticians. Perhaps it will help figure the variables. It does seem like this light is not running very hard at all and should be doing more. (UT02, I mean)

Yes they are fine, but they’re also a couple of MB and not worth the huge size.
Takes very long to load with the number of pictures on page 1.
1000 pixels width would be more than enough.

Could be a little higher, but you lose efficiency because you need the boost driver.

That’s the advantage of a boost driver. :slight_smile:

I have set the pictures based on the width of the page . Works best in most devices .
If i set them based on pixels they will not show properly on smartphones etc . Anyway , i will reduce the pictures’ relative width .

I am curious what different efficiency values different types of drivers have. I also read that modern boost drivers are much more efficient… If I look at the runtime graph of the U21, I’m pretty pleased.

That doesn’t matter.
You have used a lot of pictures of several megabytes each.
Setting the % page width doesn’t matter, it takes unnecessarily long to load anyway, because the files are huge and many in number.
You should scale them down on your PC first before uploading.

Not complaining, but I also have noticed page 1 takes a lot more time than any other page to load…

Ok i will probably do this when i update the review .

Thanks for letting me know , and sorry :slight_smile:

Good point, because i forgot that a linear driver just turns the surplus Voltage to heat = waste.
But in this case the voltage has to be quadrupled (that’s 4x) approximately, which is usually not that efficient.
A.f.a.i.k. boost and buck conversion works much more efficient when it’s within about 20% difference between input and output.

:+1:
Thanks.

Peak output being at 2.5A which occurs with 14.4V, or thereabouts, voltage is a bit more than tripled, not quadrupled, but still… the constant current style puts a heavy load on a dying cell by maintaining voltage at the cost of ever increasing amperage draw from the dying cell. Sounds problematic to me, considering that a hot cell can be a bomb. Factor in weak, cheap, and/or inferior components on the driver to save every fraction of a cent and it’s not a likely candidate for bumping power to for just anyone.