MagLite 2C LED drop-in Technical Review

[Jarhead]

Okay, so what makes this sucker tick, and how does it actually perform?


First, the drive waveform on the pins of the LED, from the switcher that is built in:

http://www.molalla.net/~leeper/mag2cled.jpg


I mounted the drop-in module into a 2D-Cell light, so that cell voltage drop would have much less of an effect on measurements.

Next we have preparation of the MagLite 2C LED module, where I have drilled into the side of the Luxeon, to access the Luxeon slug, backfilled with thermal grease for temperature measurements:
http://www.molalla.net/~leeper/ma2cledh.jpg


Showing the K-type thermocouple wires stuck into the hole, notice how fine of a guage they are:
http://www.molalla.net/~leeper/ma2cledt.jpg


Here is a picture of part of the setup after the 30 minute test was over:
http://www.molalla.net/~leeper/ma2cledm.jpg


The interesting thing here is to note just how hot the LED slug gets, and how it's light output drops as it heats up. We are looking at nearly a 60% drop in output, due to the LED getting hot, from a severe lack of good heatsinking:

http://www.molalla.net/~leeper/ma2cledg.png


At the beginning, I measured an input voltage of 3.109 V from the batteries, pulling 1,320 mA. This works out to 4.10388 Watts input. I did not have time to modify the output so that I could measure current to the Luxeon.

At time zero, I got 3.986 V across the pins on the LED in the module. This is the voltage applied to the LED.

The voltage to the LED rapidly drops, stabilizing over time, as the module heats way up.

Towards the end of the 30 minute runtime, the current dropped to 410mA at 2.95V on the input side, with only 3.115V on the Luxeon pins, after the MagLite drop-in heated up to 72.7 degrees C (162.9 F) on the LED slug.

As the module heats up, it looks like the circuitry severely kicks back the power to the LED, resulting in a major drop in output.

It would be interesting to see how it would perform with better heatsinking.


If I have time, I will do a better set of measurements, monitoring additional parameters.


For those who would like to follow additional future testing, and/or see the photos right in the thread without having to click on each, my home forum for this type of thing is here:
http://candlepowerforums.com/vb/showthread.php?p=1431904#post1431904

 

[ruffilb]

Wierd post, but :thumbsup: anyway. Would be better if the

 

[Rubycon]

ugh! not heatsinked enough.

 

[KillerCharlie]

Wait... this is just a flashlight right?

 

[Pepsi90919]

 

[KMurphy]

It would have been a more meaningful test if you used a DC power supply as your voltage source. During that time, the batteries' output voltage would drop significantly; skewing your results.

 

[Rubycon]

Originally posted by: KMurphy
It would have been a more meaningful test if you used a DC power supply as your voltage source. During that time, the batteries' output voltage would drop significantly; skewing your results.

The TPS circuit would just clamp sooner if the input was regulated. The upward impedence shift of the power source (pila) acts as a safety device - sort of.

Heat sinking LUX's is VERY important. Five watters generate a LOT of heat and the smaller devices BARELY can rid of it without becoming uncomfortably hot to hold in hand. As a matter of fact, if they are allowed to sit while running they can reach temperatures in excess of 160F which is mighty uncomfortable to hold. It also hastens the degradation of the emitter substantially.

 

[Jarhead]

Originally posted by: KMurphy
It would have been a more meaningful test if you used a DC power supply as your voltage source. During that time, the batteries' output voltage would drop significantly; skewing your results.

Since they are normally used in flashlights, it is quite meaningful, as cells naturally sag.


But, the test is only 30 minutes long. If you know anything at all about D cell batteries, you'd know they have over 20,000 mAH capacity. Thus, during this time, the cells are only depleted less than 5%.

So, in reality it has very little effect at all.

There is more testing info on this now in the other forum, if you are interested.

 

[0roo0roo]

nice

and thats too bad its not heat sinked enough

 

[0roo0roo]

you should post this in candlepowerforum, they would want to know this

 

[Jarhead]

Originally posted by: 0roo0roo
nice

and thats too bad its not heat sinked enough

I'm the one that first mentioned heatsinking, if you look up...


Anyhow, it sounds like a great opportunity for someone to create one.

 

[KMurphy]

Originally posted by: Jarhead

Originally posted by: KMurphy
It would have been a more meaningful test if you used a DC power supply as your voltage source. During that time, the batteries' output voltage would drop significantly; skewing your results.

Since they are normally used in flashlights, it is quite meaningful, as cells naturally sag.


But, the test is only 30 minutes long. If you know anything at all about D cell batteries, you'd know they have over 20,000 mAH capacity. Thus, during this time, the cells are only depleted less than 5%.

So, in reality it has very little effect at all.

There is more testing info on this now in the other forum, if you are interested.

If you knew anything about battery ratings period, you would have posted the other rated information that goes along with any battery manufacturer claim; there is also a final discharge voltage rating associated with the discharge rating which is much lower than the nominal float or stand by voltage. Once a battery's voltage has depleted to less than ~85% it is basically useless.

BTW, please show me a "D" cell battery that is rated to deliver 20 amps for any significant period. Even a dead short across the terminals won't yield near 20 amps.

 

[Rubycon]

Originally posted by: KMurphy


BTW, please show me a "D" cell battery that is rated to deliver 20 amps for any significant period. Even a dead short across the terminals won't yield near 20 amps.

While it's not a typical axially terminated "d" cell, a Gates® Cyclon® tabbed "D" cell can provide over 125 amperes into a dead short shunt test rig!

High capacity nimh cells can probably belt out some high amps into very stiff loads too. They most definitely put the standard alkaline cell to shame.

20Ah in a D cell is definitely at a c/10 or lower rating. I have some 5.5 Ah nimh c cells for portable strobe units and they are rated in a similar manner.

 

[mercanucaribe]

Originally posted by: MS Dawn

Originally posted by: KMurphy


BTW, please show me a "D" cell battery that is rated to deliver 20 amps for any significant period. Even a dead short across the terminals won't yield near 20 amps.

While it's not a typical axially terminated "d" cell, a Gates® Cyclon® tabbed "D" cell can provide over 125 amperes into a dead short shunt test rig!

High capacity nimh cells can probably belt out some high amps into very stiff loads too. They most definitely put the standard alkaline cell to shame.

20Ah in a D cell is definitely at a c/10 or lower rating. I have some 5.5 Ah nimh c cells for portable strobe units and they are rated in a similar manner.

What is c/10? Where do you get 20Ah D cells?

 

[Rubycon]

C/10 means the current rating divided by ten. Thus a 100 Ah pila could provide 10 amps for ten hours. It will NOT provide 100A for 1 hour.

I'd like to know where 20Ah D cells can be obtained as well. Those Lithium Sulfur cells used for miners' lamps have that kind of capacity but at perhaps a C/200 rate. :Q

 

[Jarhead]

The 20,000 mAH E95 Energizer Alkaline D cell has it's rating at a 25 mA discharge.

The cell drops to 10,000 mAH at a 500mA discharge rate.

The MagLite 3W LED bulb drop in, drops below 500mA within the first 10 minutes, and at 30 minutes, is around 420mA draw.

As such, (quickly below 500 mA), one would get roughly 20 hours out of the E95 Energizer Alkaline D cell.

Datasheet can be found here:
http://data.energizer.com/PDFs/E95.pdf

 

[Rubycon]

Originally posted by: Jarhead
The 20,000 mAH E95 Energizer Alkaline D cell has it's rating at a 25 mA discharge.

The cell drops to 10,000 mAH at a 500mA discharge rate.

The MagLite 3W LED bulb drop in, drops below 500mA within the first 10 minutes, and at 30 minutes, is around 420mA draw.

As such, (quickly below 500 mA), one would get roughly 20 hours out of the E95 Energizer Alkaline D cell.

Datasheet can be found here:
http://data.energizer.com/PDFs/E95.pdf

The datasheet also shows cell life ending at 0.8 volts. At what point does the driver fall out of regulation or switch to direct drive? 20 hours seems very stretched given the cell voltage declines with use. It may produce light for 20 hours but surely at much less than initial starting output.

 

[Jarhead]

Originally posted by: MS Dawn

Originally posted by: Jarhead
The 20,000 mAH E95 Energizer Alkaline D cell has it's rating at a 25 mA discharge.

The cell drops to 10,000 mAH at a 500mA discharge rate.

The MagLite 3W LED bulb drop in, drops below 500mA within the first 10 minutes, and at 30 minutes, is around 420mA draw.

As such, (quickly below 500 mA), one would get roughly 20 hours out of the E95 Energizer Alkaline D cell.

Datasheet can be found here:
http://data.energizer.com/PDFs/E95.pdf

The datasheet also shows cell life ending at 0.8 volts. At what point does the driver fall out of regulation or switch to direct drive? 20 hours seems very stretched given the cell voltage declines with use. It may produce light for 20 hours but surely at much less than initial starting output.

The 2D MagLite 3W LED module is not a buck module. They use a boost circuit. Remember, a fresh set of cells is around 3.1V, and the LED's Vf is higher then the cell voltage. As such, they don't really switch over to direct drive, like some buck circuits do.

I have not yet measured the cut-out voltage. I can tell you it still works at 1.45V in, but it will only pull 182mA out of the cell. As such, this is well below the 0.8V of 2 depleted D sized Alkaline cells.

 

[biggestmuff]

You're in prison or something, right? I don't see how someone would waste their free time doing something like that. I mean thi is beyond "nerd". I don't even know what I'd call it. For your next project, why don't you study how many times that serrated edge on an aluminum foil box can cut a sheet of foil properly before going dull. Geez, guy.

 

[Jarhead]

Originally posted by: biggestmuff
You're in prison or something, right? I don't see how someone would waste their free time doing something like that. I mean thi is beyond "nerd". I don't even know what I'd call it. For your next project, why don't you study how many times that serrated edge on an aluminum foil box can cut a sheet of foil properly before going dull. Geez, guy.

Okay, thats the first time I've been called an uber geek by a computer geeky type person.

Buddy, you'd probably be surprised at things I study in detail. And can you imagine, I served as a US Marine for 12 years. How do you think all these gadgets (DVD, Computers, IPOD, Blackberry, Cell Phone, LCD, etc.) people enjoy, are designed and created?

Myself, I design equipment that allow pilots to navigate and such, if you must know.

Anyhow, there are alot of updates and comparisons in that thread over there now.


Thanks for the complement biggestmuff.

Hope you have a great day biggestmuff, and I hope you appreciate those who answered the call, and the folks that didn't make it back- who paid the ultimate price.

For those who are serving now, or have served, my hats off to you!