3cell overdriving info.

Ok this may be old news to many of you but for an idiot like me who keeps blowing up bulbs while overdriving them this may help.

Ok, I knew that for a while I had successfully overdrove a Philips KPR102 in a 3Dcell, and it was super bright. I never had any problems with it. Until one day it just blew when I turned it on. I quickly replaced the bulb and blew that one two. I couldnt figure out what was up, I wrote it off to just having had a super strong freak bulb the first time.

After joining the forums I read that others had successfully overdrove a KPR102 in a 3cell light. So I tried it again and blew up another bulb. Then I saw a post that said the Surge could not handle lithium batts. The bulb would blow up due to the lith batts extra voltage. This got me thinking, then through some conversations with Ratso and Txwest in some of my other posts they gave me some more insight to my problem, and it finally dawned on me, I had changed the batteries in my 3Dcell light to new fresh ones, and the extra voltage is what was blowing the bulbs.

So at the expense of a few more bulbs I did some more testing as to what the voltage threshold is for a KPR102 in a 3Dcell light. This is what I've found.

First off, a KPR102 overdriven in a 3Dcell light with weak batts is still brighter than a correct 3Dcell bulb (KPR103)in the light with brand new batts.

The threshold seems to be about 4.555 volts (total voltage added of the 3Dcells) before the KPR102 will blow. I know for sure that they will blow at 4.665. (I get the battery voltage from my Radio Shack digital multimeter).

I think I've gotten close enough to the threshold of the KPR102. I've run it for about 5 minutes constant at that voltage without a problem, and maybe 15 minutes total time (on and off). And it's pretty bright like that, much brighter than stock.

Anyway I just though this info might be able to save someone some bulbs, and make the world a brighter place! LOL

--

KartRacer31

Welcome to the Flashaholic sport of matching remaining voltage in a group of batteries to the bulb you want to drive. With alkalines starting life at 1.6 volts and finishing useful life at 0.7 volts you can optimally redeploy any given battery many times over its life.

I won't tell you the extreme game of musical batteries and bulbs I sometimes play starting with a bulb I'd use with 4 fresh alkaline AA's and finishing with the same bulb in a DB8AA wired in serial with 8 weak AA's. Brock is the original master at this game although he doesn't take it to the extremes I do for the fun of it.

One of Brock's favorite doctrines is that alkalines spend most of their useful life between 1.0 V and 1.2 V so he moves batteries out of their fresh new deployment (maybe 20% to 30% of life) to this second phase on a regular basis.

As overvoltage tolerance is a function of overvoltage percentage -- not absolute overvoltage -- the fewer batteries a bulb is designed for the less tolerant it will be of one additional fresh battery.

lemlux - Indeed this opens up a whole new avenue in my flashaholism. Ha, and my wife thinks all I do is collect flashlights!

Now if a good storm would just roll in and we'd loose power for oh a week or so I'd be real happy!

KartRacer31

One basic suggestion is to get a JBechtoe 4 LED PR bulb that is optimized for 4.5 to 4.8 V.

Drive it with 3 fresh alkalines (and a dummy if you have a 4 cell light.) Drive it with 4 NiMH's. Drive it with 4 Weakened alkalines.

Ok, I'm really new to the LED lights. I only have one, and while I appreciate it's long runtime and cool looking light, I'm not very impressed with it's output. Its the dorcy 4aa light. What will this JBechtoe 4led pr bulb do for me? How bright is it? I imagine if you can overdrive an led that would be good, it would be brighter, and cutting the run time down will still give you like a million hours of burn time.

And where can I get a dummy battery? Does anyone sell actual dummy batteries, I've never seen them. Where can I get one? Thanks --

Not even realizing I had done so I was messing with one of my Sams Value Light 3Ds and it was nice and brite. I pulled the bulb to test a Mag Xenon Star in it (conclusion due to the compactness of the Xenon any light one goes in should have adjustable focus). Upon re-installing the original bulb it went blink. It was a KPR102. It had lived happily for some time, though not being used much like most of my lights, and I didn't change batteries or anything. But when it's time came... it went!

Come to think of it, I need to find some Xenon bulbs for a couple of different 3 cell lights.

KartRacer,
If your Dorcey 4AA LED light is a "Kool Blue", you'll find JB's 4 LED bulbs totally different. The color will be much less blue (closer to white), and much brighter (4 LED's VS 1 LED). And the coverage area will be much wider, as opposied to a "spot" type throw. TX

Where would you find the JBechtoe lamps?

Streamchucker

JBechtoe is a CPFer who lives North of San Diego.
The last time I contacted him he could be reached at:

[email protected]

TX,
How do JB's 4-LED lamps work with a smooth reflector like the Dorcy Kool Blue or the Turtle Lite II? Just wondering if you had one.
John

Minor non bothersome artifacts with these smooth reflectors.

Smoother effect in a PT40 or a Dorcy Boss with orange peel reflector.

Lemlux,
Thanks - I'll probably use my smooth reflector light with a single LED lamp tweaked for optimum focus and the 4-LED lamp with the faceted reflector. Thanks again!
John