Can RCR2 be used with KI with SCIII converter?

Those of you who have KI (either LE or the normal bead blasted), have you guys tried using RCR2?. From what I read in original KI (CPF LE) thread, it stated that the maximum Vin would be 6V and it is a buck/boost converter, so I'm assuming that RCR2 would be fine. I've just got myself a KI (bead blasted version) with SCIII converter running 400milliamp, when I used normal CR2 I got about 600lux on the light meter (LM631). When I inserted RCR2 (rested overnight 4.13V) I got almost 1050Lux. That's like almost double the Lux reading?, is this normal??. I quickly turned it off cos I don't want anything funny happened to my newly arrived KI.

If you have KI (any version), have you ever tried using RCR2 and measure the light output?. I'm just wondering if mine is behaving normally.

Thanks

That's what I've been wondering about too because the SC3 is supposed to be a buck/boost converter. From what little I understand of electronics, current should be constant throughout the whole voltage range so there should be no difference in brightness whether the input voltage is 3V or 4V.

The behavior you're describing sounds like it's in direct drive when you're using the RCR2.

Maybe the electronics gurus can chime in on this one.

Thats what I thought too when I turned it on with RCR2 in it, I was thinking this is waayy too bright so thats why I turned it off right away. If its a buck/boost converter the Lux reading should not change much at all.

Yeah ... Hopefully some electronic guru can explain why...

The only KI lights that can use an RCR2 cell is the KI-LE, "The cpf Special."

All other KI lights have voltage boost converters. The more the V the higher the beam is and the hotter the light gets.

This is the picture of the KI bead blasted Light engine, to me that looks identical to the KI CPF LE

With that kind of increase in output, I suspect the RCR2 kicked it up into DD.../ubbthreads/images/graemlins/mad71.gif/ubbthreads/images/graemlins/mad71.gif/ubbthreads/images/graemlins/mad71.gif

Actually the converter would have "realized" it was not needed and the switcher function would not have actuated, but long term effects of bypassing such a circuit are not yet known.

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MR Bulk said:
but long term effects of bypassing such a circuit are not yet known.

[/ QUOTE ]

Yes they are... I and others have mentioned it a number of times when the topic comes up, I believe someone asked something similar in one of your threads a while back and you acknowledged the information I posted and went on. /ubbthreads/images/graemlins/crazy.gif Don't your lights that use Pilas do the same thing? It's effects have been seen visibly with Arc AA and AAA lights too, they don't take very long to occur.

If you overdrive an LED, which is what happens if the battery voltage is above the LED forward voltage on a boost convertor, the LED will shift in color towards the bluer areas and its life is greatly decreased. You will notice, depending on how high of an overdrive, a decrease in brightness within a number of hours of use. You go from a lifespan of tens of thousands of hours, to mere hours, or hundreds of hours. Depending on the amount of the overdrive, the progressive degradation of the output of the LED essentially relegates the diode to not much more than a fancy incandescent bulb that you can count on replacing.

Underdrives shift the color towards green if highly under driven (say < 350mA for a Luxeon III), and greatly extend the lifespan of the LED.

The effects of overdriving an LED were evident with Arc's 3x overdrive of a little Nichia LED at 60mA instead of 20, and those lights were an angry blue color. Whenever people bought new ones they wondered what Peter had changed, because they were noticably brighter than their older ones they'd be using for a few months - nothing had changed, the LED had just been dimming from too high current levels.

More on topic to the question at hand - since it's a boost convertor, it did, likely, go into direct drive as MR Bulk mentioned since the battery voltage is higher than that of the LED. However, you have to be careful when doing that, the current still passes through the convertor even if it's not regulating anything, and some of them cannot stand up to higher voltages (best to ask the designer what that maximum input voltage is).

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TrueBlue said:
The only KI lights that can use an RCR2 cell is the KI-LE, "The cpf Special."

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Since it's using the same SCIII converter, it should be no different than the KI-LE's.

[ QUOTE ]
All other KI lights have voltage boost converters. The more the V the higher the beam is and the hotter the light gets.

[/ QUOTE ]

This is exactly what seems to be happening to bajaiman's light that has us scratching our heads.

Hey Endeav, if you'll look more closely at your own quote of my post you'll see that I was referring to the circuit. I agree that long term effects of overdriving any LED are indeed known, which is why even on the Lion-type lights there is a two-wire desolder/resolder routine to replace the LED if it ever came to that. Of course given the evolutionary speed of LED technology recently, by that time you'd be replacing it with a Cree ChromaLED or Nichia Pluton or Lumileds K2 or even a Lumileds ... K20? /ubbthreads/images/graemlins/grinser2.gif

Thanks for the input guys /ubbthreads/images/graemlins/smile.gif, hopefully Arc mania himself can chime in if he stumble across this thread.

Anyway…I'm sure some of you guys that own KI CPF LE also have unprotected RCR2, I was just wondering if you got any chance to use RCR2 on your KI, and if you have a light meter would you mind post the Lux reading with normal CR2 and RCR2?

Thanks.

Bajaiman,

It was one of my plans to use RCR2 when I got my light but after reading about experiences like yours, I've been wary of trying it for fear of frying the light or even just shortening the led's lifespan.

I believe that I asked ArcMania, if rechargeables could be used
in the KI?(sometimes my memory is "OLD"). Can't locate the communication, but recall he suggested that it would not be a good idea.

jeffb

chrome KI has a boost only circuit. I've use CR2 li-ion with no problems. your mileage may veri..

cpf KI has buck/boost and can use li-ion safely.

I didn't know there are 2 version of SCIII (boost and buck/boost. Just a thought…maybe my KI light engine is the same one with the upcoming KI-T /ubbthreads/images/graemlins/naughty.gif which has a boost only converter with 600 lux for 2 hours.

If bead blasted/chrome KI has only boost converter then I'm not putting that RCR2 in it then, not worth overdriving the poor LED. If I want power I can always have my RAW to get 1600 lux, now that's POWER!! yeah baby! /ubbthreads/images/graemlins/grin.gif

Guess its time to order some CR2 from batterystation and check the runtime, hopefully it'll run for 2 hours on a single CR2 /ubbthreads/images/graemlins/grin.gif.

When I ran CR2 in chrome boost only KI. light went into DD and was way brighter.

li-ion CR2 is the only way to go with such a small cell. Side by side both Ki's runing CR2 li-ion. boost only version is brighter.

possible problems of luxeon drawing too much current if Hbin 3watt is used in your KI.

in DD with li-ion, Kbin will draw aprox. 1.2amps, Jbin will draw aprox. 1.6 amps, Hbin will draw aprox. 1.8amps

naturally draw is a function of lux's VF. Do a simple current measurement to determind what's happening..

The converters do look the same but only one person really knows what is in the cans. ARC mania...are you nearby?

I suspect even with a buck configuation the converter cannot complete squeeze back the extra voltage. It would be like a dam; the majority of the voltage would be held back but if there is too much then some of the voltage would spill over. /ubbthreads/images/graemlins/icon3.gif

ARC mania...where are you? Didn't Jimmy Olsen have his ultra-ULTRA sonic watch that only Superman could hear? Zeee...zeee...Zeee...zeeee. /ubbthreads/images/graemlins/smile.gif

MR Bulk - misunderstood you.

For what it's worth, I ran a red Luxeon III a bit above 2 amps on accident for about 3 minutes (not continuous) testing. A new one at 1A was noticably brighter after that time period - slamming the LEDs with higher-than-spec current levels isn't the best idea, especially not in the KIs, the LED would be a pain to replace, I'd imagine.

...Zeee, zeee.
.
..
...

The answer from ARC mania:

Sorry for the late response. What I can't figure out is why people have to use a rechargeable CR2. To me, since the capacity is only like 400ma to 480ma (even though some claim 550ma.)

The SCIII has no over discharge protection and none of the current CR2 batteries have over discharge protection as well. Why go through the hassle of keeping tabs on a rechargeable CR2 to prevent destroying it? Plus the capacity is so low that run time is very short. It just doesn't make sense to me.

Anyways you have answered the question correctly regarding the brightness increase as well as the additional heat when a rechargeable CR2 is used.

Using the rechargeable will not damage the converter and it will stay in regulation. It does not go into DD. I made the SCIII to handle more voltage because there are curious people who would actually stuff a rechargeable CR2 in a boost only converter. When this is done in a boost only converter, the components get fried and doesn't regulate properly. People want to stuff a lithium ion 3.7 volt battery in everything they get their hands on.

It would be nice if ARC mania would post here himself. I exchanged email with him about this a while ago, and got a similar response.

ARC mania says the KI stays in regulation with an RCR2, but mine and a friend's are both much brighter on RCR2 than on a fresh CR2, and I measured mine at 1500cd on RCR2 versus 900 on a fresh CR2. (In a repeat experiment, another day, 1275 vs 800.) I accept that this isn't DD, but I'd like to understand more about the regulation. For what it's worth, this light output is still comparable to that of an HDS EDC, and HDS explicitly say they don't overdrive their LEDs, so maybe it's okay.

Why you'd want to use an RCR2 seems obvious: KIs burn through batteries, so an RCR2 is more economical. If you're only using it for brief periods the RCR2 will suffice, and you can keep it fully charged, which you can't do with a primary CR2. At as little as $3.80 for an RCR2, even if you destroyed it after a few uses it'd still be economical.

-Greg

So final verdict is we can?