Full voltage break-in period required for LuxV KL4?

Howecollc

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I'll start with my question; anyone interested in all the specifics, read on below.
Could my LuxV KL4 need some type of break-in period utilizing the full voltage of 2 CR123 primaries before it's able to properly run with an RCR17670?

I bought a Surefire LuxV L4 back in 2004, and after running thru 2 or 3 changes of primaries, decided to make the investment in rechargeable 17670s. I never fed another primary to it after that. A behavioral difference I noticed with the 17670 was that when the battery was almost at the level of depletion which would cause the KL4 to kick out of regulation the switch would become very "flickery". The range of motion during momentary activation would cause the light to vary from full output to slightly reduced output and back and forth. However, clicking to constant-on always resulted in steady yet slightly reduced output. This behavior always occurred within the last minute or so of regulated runtime, then the regulation kicked out and the light went to moon mode. My brother also had an L4 which behaved pretty much identically, so I chalked it up to normal behavior resulting from the switch's inherent resistance intensified by the increased current draw of the KL4 running on only 3.7 volts.

Cut to a little more than a year ago: My KL4 had seen so much use that its original output had steadily diminished to the point where it was pathetic compared to my brother's; and only 2 of the 4 dies lit up when it was in unregulated moon mode. I decided to send it back to Surefire after verifying that they still had some of the LuxV KL4s available for warranty replacement. The new KL4 they sent me was never fed any primary batteries; as soon as I received it, I promptly filled it with a 17670 and fired it up to see what it looked like. It was certainly nice and bright, however, after the first 5 or 10 minutes of runtime on every freshly charged 17670 I put in it, I was getting the odd flickery switch behavior and somewhat less than full output when the switch was clicked to constant on. Basically the same behavior as that of the old KL4 during the last minute of a battery's runtime, but now I had to live with it for 35-40 minutes. I tried 3 other Surefire clickies I had available and got the same behavior. If I removed the switch and instead made firm contact with a piece of wire, I got full output. My original KL4 (one of the old 65 lumen rated models) had pulled 1.5A, my brother's pulled 1.67A, and the new head pulled 1.83A (pretty much crushing any thoughts I had of one day putting together an RCR123 powered TW4). I decided that either that extra .16 amps was to blame or possibly this particular head had a slightly out of spec Vf or some other LED spec beyond my limited understanding. I just accepted getting used to having 5 minutes of full brightness followed by 40 annoying minutes of still good, but nonetheless, slightly reduced output. In time I ended up getting an F04 diffuser for my E2DL, and relegated the L4 to secondary duty.

Cut to last week: I had no rechargeables available, so I put a set of CR123 primaries in the L4, thinking it would be nice for a change to use it without all the annoying flickering and dimming. It ran at full output as expected, and kicked out of regulation after probably an hours use (with no switch flickering beforehand). The surprise came when I put a 17670 back in it and went thru a whole 45 minute run with none of the previous issues. I probably clicked the switch a hundred times that day just trying to get it to flicker or dim. I put another 17670 in it, and again, no more issues. The current draw is still 1.83A, so that didn't change. I'm absolutely certain that that was the first time any CR123s had ever been put in the light; I had run only RCR17670s in it from the moment I received it.

Anyone have any idea what effect the extra voltage of the CR123s might have had on the circuitry to make my problems go away?
 
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Bullzeyebill

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Man, I'm stumped. I have had 3 KL4's and they all ran at full output with one 17650, never used 17670's. How is the overall length of the 17670 compared to two CR123's? Just thinking out loud here. Maybe pressure on the tailcap, causing problems. I have had problems with overally long Li-Ions in some of my other lights.

I used an 18650, and 18670 (Pila) is a 18670 body without problems but the body was longer than a stock L4 body.

Bill
 

Howecollc

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I got the same results when using any of my 17670 cells. My old Pila 600S, and my even older Pila 168S cells are about 1 mm longer than 2 CR123s in series. My AW 17670 is about 1 mm shorter than 2 CR123s, but had the same issues as with the Pilas. I actually bought the AW 17670 thinking that it might be capable of higher current draw than my aging Pilas, however, the flickering and dimming continued.

But like I said, the problem seems to be mostly gone after having run primaries in the light for about an hour. A single 17670 now works almost perfectly, with the exception that instead of having full output up until 15 seconds or so before the light kicks out of regulation, I seem to be getting about 4 or 5 minutes of gradually dimming light and then it finally abruptly kicks out of regulation. I'm just curious about what the temporary use of primaries changed within the head; and I hope the issues don't gradually come back with time.

Since the problems completely disappear when you eliminate the extra resistance of a clicky switch, and I've just recently switched to using a Malkoff M30 for my everyday worklight, I've been tempted to finally relegate the KL4 to IMR powered TW4 pocket status with some type of twisty interface. Some retailers seem to still be offering older E1e models with the twisty switch, but they may simply be using outdated pics and descriptions. I actually prefer the size of the new Valiant Flat Twisty but I don't see Olive Drab coming back in vogue any quicker than avocado green appliances.
 
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