High current Kroll mod attempt - a night of frustration

Well, like they say... "if at first you don't succeed, try, try again"... which, I will. But, I sure as heck wouldn't mind some advice from those who have tried, and lived to tell about it. If I may be so bold... McGizmo, LEDzeppelin...?

Spent five hours straight last night, trying multiple times, in various configurations, with both 22ga. wire, and solder wick, to eliminate the (rough estimate, 250mOhm) resistance in a Kroll switch, and allow it to handle 2 Amps current @ 7.2V. Taking the idea from past posts regarding D and C size Mag switch mods, the plan was to utilize similar techniques to lessen the resistance, and improve mechanical contacts. Here's what I did, and the problems that occurred. Anyone that comes up with a slick solution before I do (after tonight, who knows when that'll be), will receive a voucher to have their toes kissed...

...by my Aunt's dog... lol. What, you though I was gonna' do it? :sick2: Besides, there are few things more heavenly than being kissed by a canine. Dog lovers need no further explanation.

The short version... As one might guess, the first thing I did was bridge the batt contact spring to it's neighboring plunger contact spring, trying both wire, and solder wick. Second was to make a bridge horizontally within the spring itself that contacts the plunger's other side to the Minimag tube. To reiterate, and amplify... I tried the 22 ga. wire, AND solder wick in every different combination. Wire on all springs, wick on all springs, various wire and wick combos on the springs, and vice versa, wrapping to the inside, wrapping to the outside, tried to be as neat and clean with soldering as possible, etc. In hypothesis, it should work somewhat easily... but the problem is TOLERANCES!

After many tries, constantly improving on each attempt, I got close, but no cigar. The best I could do was maintain spring contact on both sides of the plunger, by full thumb pressure in momentary position. As soon as the button is released into latch-on position, the contacts break. Obviously, full-off is not a problem. :ironic: Edit: Which is a desired safety feature here, considering two Li-ion batts in series in a pretty small package, powering an extremely bright, yet small incan bulb.

Summation: :hairpull: Trying to mod the Kroll while retaining it's original config, I just can't get the proper tolerances by hand.

Question: What's the solution? Some uber-cool solution to make plan A work (the German in me has a certain affinity toward this approach), or a LEDzep, approach where a mass manu. switch gets stuffed into a Kroll housing. Still not sure of what Don has done in this area, as I'm not familiar with some of the clicky parts I've seen on his site.

Any advice from some clicky mod veterans?

Edit: This is for running a Carley H1499 (thanks, Litho123!) off two 14670's (thanks, AW!), off an extended 2AA MM tube (thanks, Ledean!).

I also would like someone to chime in on this. The Kroll, even when pampered with Dextroit cleaner and prepped with ProGold has too much resistance built in. The most you can hope for is 750mA's with two quickly dropping alkaline AA's with the original Surefire AA light, or a mini mag. This is the reason I go with the twisty tailcap.

If the Shoppe would come up with a McClicky to replace the Kroll it would, or should sell like hotcakes. I would buy at least two, maybe more. Thank God there was an after market twisty for Mr Bulks VIP as the Kroll will not sustain the 1 amp to led upgrade I had performed on one of my VIP's, as it pulls well over 2 amps from two NiMh AA's. There are lots of high end lights out there that depend on the Kroll. Let's keep this thread alive.

Bill

Hi, Bill. Thanks for joining in. Something along these lines would most definitely sell like hotcakes... I'd buy three or four right off the bat, and probably more later on.

People have wished for years for a really nice alternative to the Kroll, and the best that's been produced is the Terralux. IIRC, it's resistance is not much better. Haven't gotten any because of that, plus I don't care for the reverse clicky action, and prefer the Kroll's rubber dome to the Terra's non-splashable looking red button. If I had the resources, like a little machine shop, you could bet yer patootie I'd be making the perfect Kroll, and also selling them to all your patooties out there!

Update:

Another hour of playing around this morning yielded a small step forward. I still have to keep thumb pressure on the button, but for a different reason now. My last attempt doesn't allow enough button travel for it to latch. It's soooo close though... another .5 - 1mm will do it. The good news though, is it looks like contact will be maintained if I can get it to latch. The even better news is that resistance is virtually gone! Not even enough to read on an analog meter. Yayyyyy!

However, if/when this thing finally works, reliability testing will be have to be done for a couple months on a regular Minimag running alkies, before I'd trust it. Even then, it's iffy, as this hack job could break or get stuck on without me knowing it, and drain the Li-ion's 'till the cows come home... which isn't good.

Anyway, back to the lab... err, I mean kitchen table.

Don't know if my $.02 is pertinent, or not...I also went with the Ratshack DeoxIT/DeoxIT GOLD, and the results were favorable, but the greatest improvement came with greater force on the main spring (I think that is where the improvement came from anyway). I made about a dozen versions of cell tubes, in Ti and aluminum, and the ones that seem to work flawlessly are the cell tubes that collapse the spring more.

I don't have any lights that pull 2 amps, just Flu-Pic lights that pull 1.2 amps on high, but they have been working very well for the past few months, without a recoat of the DeoxIT.

I prefer the feel of the Kroll, over the McClicky...But I like the mechanical seal of the McClicky boot, over the Kroll.

Update number two:

More playing around with this thing yielded major progress. Solved the button travel issue. It now works perfectly when testing it by itself, works properly when half-screwed into a Minimag, and it's almost working properly when screwed all the way in. I think I know what the problem is, and have an idea how to fix it. The high current Kroll mod could possibly be fully operational by tonight!

Pics coming soon.

Can you measure light output (lightmeter-bounce) with a stock kroll and your "high current" Kroll. That will show the difference, it will be brighter with less resistance in path. Also, please post ohm resistance compared to stock Kroll.

Bill

Bill - I don't have a lightmeter, but from testing the little beast with a stock Kroll vs. the stock MM tailcap, the output was definitely lowered enough to tell by eye.

As for Ohms readings, the stock Kroll looked about 250mOhms, but the high current mod was unmeasureable on an analog meter.

I managed to get the readings before blowing out the meter last night, which I'm really upset about. I inherited it from my grandfather who passed away two years ago. He taught me a LOT of stuff when I was a kid, and he'd be proud to see me using his meter. Neither of the two fuses blew, so I'm quite worried something else burned out. It happened really quick, and I'm not even sure what the mistake was... just doing a simple current reading in series, and the range was properly set! Must've done something wrong though.

Anyway... gonna' try to fine tune the Kroll mod tonight, and take pictures of a couple other recent mods, one of which being what I hosed grandpa's meter with.

Some pics of the mod. I haven't messed with it since last posting, but will get a chance to in a couple days, and will try to get it fully working. After all the work on this stupid thing, it's gettin' used so there ain't no giving up now.

Ta da! The almost functional, high current Kroll. The wick bridges from the top of the battery spring, to the bottom of the much smaller and lighter gauge spring inside the housing. Not only does that eliminate the contact point between them, but that smaller spring does not look like it handles tons of current... the wick definitely fixes that.



The other side.



This is the side spring that contacts the battery tube. I believe the un-reliable functioning is due to the horizontal orientation of the wick. Seems it's being grabbed by the tailcap threads as the switch is screwed in, and the spring gets moved out of proper position. The switch's behavior seems to support the theory. I may remove the wick, and try a wire with the solder join going vertically up the spring.


More updates in a couple/few days. This thing WILL work!

Keep up the good work and post results. A nice step by step would be good for me. I will work on mine pending your results, and posts. Thanks,

Bill

Latest update:

Arrrgghhh! That's the first thing.

Still no go. But, we ain't out of gas yet. I've got numerous ideas. Like I said before... there WILL be a high current Minimag clickie!

Tried messing around with this thing a couple more times since last post, and here's where things are. With the present direction, the problem is still mainly in the spring that contacts the MM wall. It absolutely refuses to maintain proper contact with something, likely the plunger, when it's screwed all the way in. In that state, it works great as a momentary. Back it out a couple turns, and it works 100%!! Again, when holding it in my hand outside of the light, the resistance is not measureable (got a cheap DMM while I figure out what I did to Grandpa's analog), so in theory, this is gonna' work great! When?... I don't know.

In trying a new direction, I stopped at Rat Shack yesterday to hunt for a switch to bury inside the Kroll housing, a la LED Zeppelin's two-stage mod. One of their momentary's looked like it might be the shiznizzle... notice I said "almost". There were many aspects about it that would work, and the ones that didn't, I could work around. Perfect!... except for one thing. I bought it, took it home, metered it, and found the moment you back off the button so much as a few thousands, it breaks connection. That'll never work with the ratcheting action of the Kroll's button, so there's another idea down the toilet ("Terlet", for those who live in "Bensonhoist"). I was sooo desperately hoping for some travel on it... oh well.

While the quest for the right switch to stick in the housing continues, work on fixing the beforementioned spring problem goes on. I've got numerous ideas for that :devil: ... just hope one of 'em works.

As Bill points out, there are a lot of great lights out there that could benefit from increased current capability and low resistance. Two being mine... one of them especially needs this. If I can get a reliable, and somewhat repeatable solution, I'll post the details and pics for anyone who wants to do their own.

Bill - Again, thanks for the interest. If/when the reliable and repeatable thing happens, one of them is yours.

Bill's not the only one interested! I'm just hoping the final solution is something simple enough for me to replicate.

Sinjz - Haha... I hope so too! BTW, every time I go to Auto Barn, I've kept an eye out for another 4D lantern adaptor. If they ever get one in, I'll let you know!

Tranquility - Been meaning to reply to your post! Contact force is most definitely part of the equation. If only the Kroll's internal conducting springs were a little stiffer and heavier, a good portion of the troubles would likely be alleviated. There would be better contact, and the thicker gauge would have an easier time carrying high Amps.

The quest continues.

Bimmerboy: Just found this thread and wondering if you've made any progress. I've tried to accomplish the same thing by soldering a piece of solder wick from the tip of the battery spring, threading it through the smaller spring it touches, and soldering the other end to the metal, round contact that fits inside the plunger.

So far it seems to have solved that annoying feature of the Kroll where it briefly disconnects when it latches on - and sometimes latches on at a lower brightness. Made it impossible to use reliably with a flupic but now it's working o.k. so far.

Haven't been able to find a reasonable solution for the external contact spring on the side of the switch. I haven't been able to find a suitable stiffer spring to replace it. I'm thinking about soldering a thin shim to the "top" of the spring to increase the contact surface with the internal round, metal contact. If my soldering skills are up to it I'll let you know how it turns out.

Bimmerboy, I've been on vacation and in and out since then and today. Thanks for the offer. I do want you to succeed at this project. My VIP running at 1 amp to led with two NiMh's needs help. I can use the twisty tailcap, but prefer the supplied Kroll Kings Crown tailcap that Mr Bulk, Charlie, sent with the light.

Bill

Thanks for the input, guys. No major progress over the last couple weeks, but hoping to make some further inroads toward solving this issue soon. I've found a relatively local place billing themselves as an "electronic supermart", and will head over there this Monday/Tuesday.

Again, given limited resources (no machine shop), I do think the most reliable/repeatable solution is to embed a mass manufactured switch into a modified Kroll housing.... as opposed to solder wicking these lousy little springs, which makes their freedom of travel, and therefore contact with other components, unreliable.

To be honest, more playing around with the meter revealed that even the contact between the plunger and the internal spring bridged straight from the batt, was not as reliable as first thought. When it works, it works great!... but continuity is too easily broken by slight jostling of the probes. Add the problems regarding the spring that contacts the inside of the MM tube, and you've got a difficult situation. There still may be an answer in that direction, but I've imagined scenario after scenario, ad nauseum, and there are problems with every solution. Finding the right switch to stuff in this 'lil bastid is the way to go.

The right switch, among other factors, is one that is momentary, but allows continuity halfway through the button travel. That way it'll work in conjunction with the Kroll's ratcheting.

Heh... at the outset, I thought this was all gonna' be easy. :sick2:

Not giving up though... the performance of two of my important lights depends on the outcome. Plus I promised one to Bill.

LED Zeppelin sent me a single stage switch modded into a Kroll to try out the same time he was doing the dual switch thread. The switch worked ok, latched on ok, but was not set up for 2 amps, more like 1 amp. I compared runtime to my Kroll switch and there was no real difference. Make sure you find out what amperage the switch will handle.

I am using the Kroll Arc tailcap for my First Run Flupic mod, and on burst it seems to be holding up. Burst is DD and must be over 1 amp, as it compares, output wise, to my VIP running 1 amp to led (bounce with lightmeter). I of course use the twisty VIP tailcap for lowered resistance.

Bill

Bullzeyebill: I checked Judco's website and the switches that handle higher amps then the one LZ used appear to be too big to fit in a Kroll. btw, I have one of his 2 stage mods - nice work. Must have taken a lot of careful trimming to get everything to fit in the Kroll body.

This is probably a silly question, but does anyone know if a McClicky will fit in there? I realize it costs more than the whole Kroll switch, but for high current applications it would be worth it to me. I guessing it may be too tall though (?).
Edit: I've posted a question in the McGizmo forum, will see of someone replies.

Leef and Yaesumofo are building the McClicky into their battery bodies, from scratch. Probably won't be able to modify a Mag AA body to fit the McClicky. Would be great if it could work.

Bill

Judging from the dimensions provided in the McGizmo forum (thanks Ganp) it looks like the McClicky is a little too big. I measure the major dimension of the Kroll at 15mm vs. 17mm for the McClicky. Judging from pictures of the McClicky there isn't much that can be trimmed to reduce it's diameter.
I may be able to get my hands on a McClicky from a friend this week so I'll try to confirm that, but it doesn't look good - not quite out of ideas yet though. Will keep trying to find something suitable that might fit in there.

What about the Nite-Ize clicky mod for AA minimag:
http://www.zbattery.com/luc-5200.html

Or possibly the TerraLux TCS-1 Tailcap Switch:
http://www.zbattery.com/tcs-1.html

Ram Lighting Tailcap Switch:
http://www.lighthound.com/index.asp?PageAction=VIEWPROD&ProdID=1772

The Ram Lighting looks a lot like the Nite-Ize, but the TerraLux looks different. Testing the resistance of those switches might be worth it.

Edit: Wayne @ ElektroLumens has been using those Nite-Ize switches in his Lucidus XR-2 - with 2 x 2009A-SHO Micropucks which put 850-900mA to the LED. Who knows what kind of loss is there - but it's worth a try. (Check third pic from top)
http://elektrolumens.com/Lucidus-XR2/Lucidus-XR2_Additional_Pics.html

Also, the same eBay seller has the TerraLux and the Nite-Ize switches, for $4 and $3 respectively - they'll combine shipping for $4.50 for both. You could get both switches to test for $11.50 shipped. (Cheaper then many online places who charge $6 for shipping, i.e. Lighthound)
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250138223746
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250138021359

Last edit: You can order the first two switches (Nite-Ize and TerraLux) from ZBattery and choose Priority Mail and the total is $11.07 with shipping.