Unhappy with the Fenix LD12 -- poor runtime chart (no PWM just noisy circuit?)

hiuintahs

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I really like the Fenix PD32 series. In fact I've modified two of them to XP-G2 (nice tint to my liking). They regulate well, are efficient and I just like the size and the way they look, along with being able to run a 18650. I like the side switch even though some on CPF don't.

So I went out and bought an LD12 recently because I wanted a single AA like the PD32 and the R5 version was on sale due it being an older LED, so I thought what the heck, I was just going to put my own XP-G2 in there anyhow. Besides I don't trust Fenix XP-G2 tints (got a horrible green tint on a PD32 once).

Long story short.........I did a runtime graph of the LD12 and to my surprise, the regulation wasn't as tight as I've known Fenix designs to be. So I thought I may have got a bad light and ordered another LD12 this past week...........and it does the same thing. :hairpull:

Here is the chart showing what I'm talking about.



Note the red. That is the Fenix LD12 on the 2nd to the highest mode. The high mode was OK without too much ripple but this 2nd one down was almost like a type of PWM on there. And the mode below this one (2nd brightest one) was also jumpy. Now you cannot see it with your eyes but I have to admit it kind of bothers me as I know it can be better. I mean take a look at the EagleTac D25A........one of the best regulated lights I have tested and more efficient.

I like Fenix but something has changed in my opinion. Because I bought an LD12 right after they came out and it did not have this embedded PWM. Note the light blue trace on the run time plot. That is the original LD12 of about 2 years ago.
 
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reppans

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Unhappy with the Fenix LD12 -- poor runtime chart

.... I mean take a look at the EagleTac D25A........one of the best regulated lights I have tested and more efficient..

Thanks for sharing this, I'm into collecting efficient 1xAA/14500/sub-lumen lights, and was considering a Fenix for its reported efficiency (although no 14500 or sub-lumen). The Fenix LD12 claims ~ 300 lumen-hrs of efficiency across its modes while the best I've tested (with a light meter and stopwatch) is closer to half that (eg, ~ 150 lms for 1hr, ~ 3 lms for 50 hrs). My Zebralight SC52 also claims ~ 300 lumen-hrs efficiency across its modes, but I find its lumen scale and runtime claims to be significantly exaggerated. For me, the SC52 tests just about as efficiently as a my D25A-XML and Quark AA-XML on a lumen-hr basis. It's interesting that both Fenix and Zebralight spec sheets nearly double the claimed lumen-hrs of the D25A-X and Quark AA-X (assume half the 2AA-X).

I always thought Fenix was on the conservative side of the fence.
 

hiuintahs

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Re: Unhappy with the Fenix LD12 -- poor runtime chart


Thanks for sharing that thread with me. I hadn't seen it. It was funny reading down through there and there was some denial........Fenix wouldn't put PWM in there....would they? LOL.

Well, it doesn't look like pure PWM where the power to the LED is pulsed on and off all the way, but you don't have to change the voltage very much across an LED to affect its output a lot so what we see is something that behaves like PWM but looks more like poor regulation.........like it needs better stability on the feedback portion of the circuit. If its true from the other thread that the Fenix engineer says that there is no PWM, then I propose they did not design it as PWM but have a design issue with their regulator circuit because its not just an isolated case. It's one of those suttle issues that most people probably would not even notice...........and maybe not enough complaints to warrant a change once they are full swing into production.

Sure you don't see it and the light still works pretty good but in my opinion this is a step backward as far as reputable Fenix technology goes for a light that sells for more than $40. I also hooked the O-scope up across the LED and the voltage is not stable like you would see with a constant current regulated output.



So now we have had proof from the guys that shook the lights back and forth, from a data logging light meter, and from an O-scope across the LED. I have an email out to customer service but its a holiday over in China right now. Anxious to see what they say.
 
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hiuintahs

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Re: Unhappy with the Fenix LD12 -- poor runtime chart

Thanks for sharing this, I'm into collecting efficient 1xAA/14500/sub-lumen lights, and was considering a Fenix for its reported efficiency (although no 14500 or sub-lumen).......................... It's interesting that both Fenix and Zebralight spec sheets nearly double the claimed lumen-hrs of the D25A-X and Quark AA-X (assume half the 2AA-X).

I always thought Fenix was on the conservative side of the fence.

I still think Fenix is (was) pretty good for the most part. The mechanical aspect of them I like a lot. Being that I'm an electrical guy though, I am real picky in that area which is why I am really bugged by this LD12. I just hope this is an isolated design issue and not an intentional change. Aside from this LD12 if you get lights with the same LED, Fenix has been right up there at or near the top from all my prior testing.

I will tell you that as far as efficiency goes I found that the lights that have the capability to run up to 4.2v on an AA size light tended to not be as efficient. At least that was the case with the Xeno E03 and the Quarks that I tested. Also I found the lights that had infinite variable adjustment were not as efficient either.

I've seen Selfbuilt's charts of the Zebralight and I've always thought of them as one of the most efficient. I will say though that I just ignore what the manufacturer says in regards to lumen and just draw my own conclusion after I actually test them.
 

Mr Floppy

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Re: Unhappy with the Fenix LD12 -- poor runtime chart

So now we have had proof from the guys that shook the lights back and forth, from a data logging light meter, and from an O-scope across the LED. I have an email out to customer service but its a holiday over in China right now. Anxious to see what they say.

Good on you. Nice to see someone with the tools to do this and sending the evidence in. I'm assuming that your trace was after you switched the light on, but what happens when you do what some of the other guys were doing and changing modes after it is on? That was when the apparent PWM'ish effect was more visual.
 

reppans

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Unhappy with the Fenix LD12 -- poor runtime chart (PWM?)

I will tell you that as far as efficiency goes I found that the lights that have the capability to run up to 4.2v on an AA size light tended to not be as efficient. At least that was the case with the Xeno E03 and the Quarks that I tested. Also I found the lights that had infinite variable adjustment were not as efficient either.

I've seen Selfbuilt's charts of the Zebralight and I've always thought of them as one of the most efficient. I will say though that I just ignore what the manufacturer says in regards to lumen and just draw my own conclusion after I actually test them.

Infinitely variables are definitely not in the same league.

I was also under the impression wide voltage tolerance lights would not be as efficient, but the 3 lm low of my QAAX meters the same as my 2012 D25AX and they ran about the same my runtime test. My D25AX's 75lm/2.5hr mode meters the same as my SC52 108lm/3hr mode and sure enough they both ran to 2.5hrs (triangulates with Selfbuilt's 2.5 hrs and ZL's 50% lumen scale difference to the D25 series). Also ran the QAAX against the SC52 at max and while the SC52 was ~25% brighter throughout, it lost most of the advantage in runtime (so ~ same efficiency on lm-hrs). Yeah, the ZLs are efficient, just no where near the twice as efficient/bright as a comparison of spec sheets suggest.

Agree on the BS marketing specs... my smell test is anyone claiming over 200 lumen-hrs on an Eneloop. I tend to find 47s Quarks and the ET D25 clicky series to have the most accurate specs in my collection.
 

hiuintahs

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Re: Unhappy with the Fenix LD12 -- poor runtime chart (PWM?)

OK so I've had a little communication with customer service at Fenix and its slowly getting escalated to where they may take it more serious. We've both shared some oscilloscope plots but I'm now recommending they evaluate the actual light I sent back.

I'm just wondering if there is a mistake in the manufacturing process like a wrong part or value being installed..........just a guess at this point. I do believe that their intent is to have a good regulated circuit which is why they are so firm in saying that the LD12 is regulated and there is a certain amount of denial that they have a problem.
 
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