Mike let me borrow his light and I compared it to mine. Here is what I found.
First let me give a little explanation about how these lights work. I first found out about them while reading a forum dedicated to modifying LED flashlights.
(hey everyone has to have a hobby and the guys on that forum know a lot about LED flashlight inner workings)
All the LED lights out there consist of 3 basic components. The LED(s), the driver board and the power source.
LEDs are a current driven device, (leaving out a lot of the technical stuff) that means they are designed to be driven at a specific current. Less than that and they get dim and higher they burn out. So you can't just hook them up to a power source, they will instantly burn up. The simple way to handle this is to put a resistor in line with LED and power source. For low power LEDs this is usually the easiest and best way but for a lot of reasons, it does not work for high power LEDs.
The LEDs used in all the latest high power flashlights are mostly the Cree XML.
This LED is designed to run at 3 amps!!. You can run it at a lower current, but the lumen output will be lower. Also, if you run it at high current, you must have a good heatsink or you will destroy the LED.
When you have a light that has multiple LEDs, they can be connected in series or in parallel. Most of the time they are connected in series because if you connect them in parallel it is hard to feed them all with the same current. The guys on the flashlight forum have dissected our light and the LEDs are connected in series. The Cree XML runs at 3.3 volts when driven with 3 amps.
So, we have 3 LEDs in series, that means we need 9.9 volts @ 3 amps to drive them at their maximum design output.
The "driver" is the circuit board that is used to give the LEDs a constant current. The drivers are designed for a specific current output. So the designer of a light has to decide what current he wants to drive the LEDs at and then find or build a driver to do it. There are a lot of factors in picking a driver. For example if you don't have a really good heatsink you might decide to drive the LEDs at a lower current and accept the lower lumen output. All depends what you goal is. We will assume that the designer of these flash lights are looking for the highest lumen output that doesn't destroy the LEDs.
It gets a little more complicated because there are two types of driver circuits.The Boost driver and the Buck driver. (there is also a combination boost/buck but it is not used much)
The Boost Driver will step up the input voltage to a higher level so it can drive a bunch of series LEDs. For example, say you want to drive our 3 LEDs with one lithium battery. The Li battery is 3.7v so by itself it will not light up the LEDs. But, if you get the right Boost driver you can power 3 LEDs with one Li battery. Now remember the output of the driver is a constant so the boost driver will draw higher current form the battery than it delivers to the LEDs.
The other driver is a Buck driver. It is designed to have a input voltage higher than the LED voltage you need ( in our case 9.9v) It will draw less current than it delivers to the LEDs.
So what does all this mean with our lights? Well simple story is the two lights I tested have very different drivers in them.
First thing I did was take them apart and compare them.
I found that Mike's light was an original Trustfire and mine is a clone.
Look at the photos below.
They both have the Cree XMLs, that's good. But you can see the outer housing is different. Mine (on the left) has one more heatsink fin. The inner core (it holds the LEDs and the driver) is the same basic shape but they are machined different. Both have threads for connecting the inner housing, but the threads are different pitch. On the other side mine has a spring for connection of the positive input and uses the threading for the negative connection. The Trustfire has a spring soldered to the driver for the negative connection. You can't see the details of the drive board because it is inside the housing and is hard to open up. (I will do it on mine and post pics because I'm using mine as a prototyping platform)
So from a physical look we know they come from a different place so it is probably a good assumption they are not using the same driver. And in fact the the testing proves that. More one that in the next post.