# Resistance is Futile (mag spring resistance)



## andrewwynn (Aug 29, 2006)

click pic for the album of pictures.

I've been wondering a long time just how much resistance the mag spring has.. since even in my baddest (well most of them) mag mods i still use the stock spring. 

So i finally took a miliohm measurement (the standard way.. jam an amp of current through it and measure the mV drop).. 

the results... FORTYFIVE MILIOHMS! holy cow! That is more than double the entire resistance of my hotdriver circuit! Definitely more resistance than the smartpak and 'holy yikes' in general. 

I took a piece of 1/8th inch wide solder wick and not even soldering just wedged it between the spring at the top and the bottom.. and it chopped off 2/3 of the resistance.. down to 15 miliohms! (0.015 ohm). 

So.. guess i'll be performing that mod in the future on all my lights... I'll probably use the scrap wire i pull off the KIU ceramic sockets.. 16ga wire is 1/3 miliohm per inch.. So that will be perfect.. 

let me see.. with a 100W light and 9.5A.. that means.. 0.42V dropped on the spring.. that boils down to 317Lumen loss on a 64625 lamp!

anybody know a silver-plater? 

I've been wondering for a long time 'cause steel is just a terrible conductor.. there seems to be some coating on them but apparently not silver (what it should be).. I'm surprised it took me so long to actually get the measurement. I've been just thinking that it's a pretty thick wire even if it's steel.. amazing once the numbers are actually calculated.. 

re-working for a mag85: 3.35A x 0.045ohm = 0.15V.. that's a difference of 38 lumen... 10.65 vs 10.80V. 

Well one more thing to mod, folks... get out your soldering irons.

(oh.. ps.. sand first.. you'll not have much success soldering to that spring before sanding!)

-awr


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## daBear (Aug 29, 2006)

I've been using solder wick on the springs for some time and it does help. Thanks for the numbers.


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## greg_in_canada (Aug 29, 2006)

When I saw this I thought "no way is it that high", but looking at Wikipedia one foot of 18 guage copper wire is 6 milli-ohms, (and from a different page) steel has about 10 times the electical resistance of copper, so 60 milli-ohms per foot.

I'm guessing at the guage and length of the Maglite spring but this is in the ball park of what you measured.

Greg


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## andrewwynn (Aug 29, 2006)

and.. the spring goes round n round n round.. i didn't measure how long but a 'direct path' with some flexible wire is 1/3 to 1/4 the length for sure.. the 16ga scraps cut from making a KIU will be perfect for fixing the spring.. i'm just going to solder them right on the ends of the spring on the top.. on the bottom.. haven't decided if i'll solder on the very inside so it still has to go through a length of steel but is much easier to make.. or deal with cutting off some of the inner spring (what i'll most likely do) to make that easy to solder and shorter distance through the spring.

yes.. i was a bit amazed at first myself. I re-did the measurement several times.. i didn't try different springs.. some might have more conductive coatings than others.. but a real 'fix' is needed. 

The solder-wick on the spring in the switch drops 80miliohm from the circuit. Glad to hear that somebody (bear) has been using this fix already. 

-awr


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## ciam (Aug 29, 2006)

Maybe this is why I haven't instaflashed my 9 x AA Mag85's bulb even when I pop in freshly charged NiMHs. I wonder if shorting the spring would remove the capability to use freshly charged cells. But it's tempting because of the rather large loss in lumens mentioned here.


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## amanichen (Aug 29, 2006)

andrewwynn said:


> re-working for a mag85: 3.35A x 0.045ohm = 0.15V.. that's a difference of 38 lumen... 10.65 vs 10.80V.


Have you actually measured this or are you going off of the LED operating curve?


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## greg_in_canada (Aug 29, 2006)

That's why I used a foot in my calculation since the spring length is closer to a foot than to an inch.

Greg



andrewwynn said:


> and.. the spring goes round n round n round.. i didn't measure how long but a 'direct path' with some flexible wire is 1/3 to 1/4 the length for sure.. .
> 
> -awr


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## Rookwood (Aug 29, 2006)

One thing I tried a few months back was first grinding the small end of the spring flat and then tinning both it and the bottom of the spring with some silver jeweler's solder - I don't know what the percentage of silver is because I bummed it off of a jeweler friend, but it's supposedly at least 10% - it melts so fast, and is certainly higher silver content than the common 2% silver solder carried at most electronics supply places. The plating on the Mag springs looks like it's zinc-based.

What about soldering the spring directly to the tailcap? Or, soldering copper caps to either side of the spring?

I always wondered if there is much resistance in the Mag tube where it makes the transition from the body to the tailcap - the parts are anodized, and I don't know if that adds a significant amount of resistance.

Anyhow, interesting thoughts in this thread. Thanks for bringing this up.
Chris


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## Rookwood (Aug 29, 2006)

Well, after thinking about how my message appears, putting copper or silver on the existing spring will do nothing for the resistance of the steel. Duh! It did make for a less-intermittent connection for me, however.

You could connect the copper caps with the wick or other wire ensuring a copper path to the battery pack.

But I am curious about the tube-cap resistance, if any.


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## andrewwynn (Aug 29, 2006)

ciam... yes it gets a bit dicy with direct drive and instaflasshing .. like the http://prfix.rouse.com which drops the switch resistance to 1/6th a stock switch.. if you do that you'll be more likely to instalflash if you use an unregulated light. You do also get more bulb life if you leave the resistance in of course.

amanichen.. incandescent lamp, not LED, but yes using the formula.. but it's accurate... the formulas are extremely accurate for less than 10% voltage difference. 

greg.. yes i was adding to your comment about the 'per foot' saying that you get close to a foot once you go round and round and round. 

-awr


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## andrewwynn (Aug 29, 2006)

rook.. probably doesn't hurt to tin the ends, but it won't make a huge difference.. you are talking about changing 5mohm to 3mohm or something.. percentage big, total small... 

The part where the tailcap touches the body is machined free of anodizing of course, else there would be no current flow at all. 

Can't solder steel to aluminum, but it's a moot point anyhow.. there is so much surface area.. the contact resistance is minimal.. there is 10-20x the resistance in the spring as the spring-bat contact and maybe as much as 100x or more the resistance in the spring compared to the spring-tailcap contact (with that much surface area.. the contact resistance is probably 1/2 of a miliohm.. 

Also.. the body is an extremly conductive device.. 2.73 square centimeters of aluminum.. that's enough to carry 300A.. maybe more.. the resistance in a 2D body is.. 0.0000233 ohm.. no wonder people use alum. for flashlight bodies.

I always use pro-gold on the contacts such as the tube-cap connection.. i have actually 'burned' that contact before by opening a tailcap on a high-power light that was on. Fortunately.. surface area is the best thing to help a contact work better and that is a very large surface area... so will be extremely low resistance.

Oh.. yeah another thing.. i always sand down my springs 'til it's a flat surface else it just cuts into the battery and of course reduces the surface area greatly making it a much higher resistance contact. 

-awr


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## Robban (Aug 29, 2006)

Another thread concerning the same idea from a few days ago.
https://www.candlepowerforums.com/threads/129582


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## andrewwynn (Aug 30, 2006)

amazing timing on that post.. i just posted over there too. 

-awr


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## vortechs (Aug 30, 2006)

My Fluke77III DDM doesn't measure sub-ohm resistance well, but it showed 0.1ohm for touching the probes together and 0.2ohm resistance from the top to the bottom of the spring. I'll see if I can borrow a better DDM to try to get a reading.


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## andrewwynn (Aug 30, 2006)

not sure if the 77 does 4-digit.. the 87s you can hold a button for a second to get 1 extra digit of precision. you can also zero the reading which is important. It is not possible to get an accurate reading from simply direct-reading.. but you can do to get close is this.. run a load like your flashlight through the spring (using jumpers etc).. and measure the mV drop on the spring.. now measure the current w/o the the spring.. the spring should have a similar resistance to the meter loading.. so you will have both a mV drop and a current.. now just divide to get resistance.. it won't be perfect or as accurate as my measurement where i put 1.00 A through the spring and measure the mV drop but it will be a good ballpark figure. 

-awr


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## vortechs (Aug 30, 2006)

I tried a Fluke 79 but got the same result (0.2 Ohms in the probes, 0.3 Ohms from top to bottom of the spring in the tailcap). I'll try to find a Fluke 87 to use. 

To measure currents and voltage drops I figured I'd need to get a good electrical connection with the tail cap removed from the light. Note that it is a cmacclel clicky tailswitch. The light is a cmacclel sub-2D ROP with a tailswitch: https://www.candlepowerforums.com/threads/105826

While playing around with the tailswitch, I tried to measure the total resistance of the switch in the ON position. I noticed that I couldn't seem to find a good point on the tailcap that would give me a low resistance reading from the end of the spring to the tailcap body (the threads, etc.). Where is the electrical path on a [email protected] tailcap supposed to be (through the threads or the top rim of the tailcap?) and what are the tricks to reducing the resistance along this path. I'm remembering reading about lye and such but I'm not a [email protected] mod or hotwire expert, that's why I got a turnkey ROP. Is there something I should be doing to the threads or tailcap rim? 

I am wondering if I might be getting more resistance from the tail to body connection than from the spring. 

https://www.candlepowerforums.com/threads/105826


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## NewBie (Aug 31, 2006)

andrewwynn said:


> I've been wondering a long time just how much resistance the mag spring has.. since even in my baddest (well most of them) mag mods i still use the stock spring.
> 
> So i finally took a miliohm measurement (the standard way.. jam an amp of current through it and measure the mV drop)..
> 
> ...




Thanks for sharing your measurements with us.

The MagLite spring resistance (and in other lights), has been a well known factor for a long time, as well as the solder wick trick. Another technique is the copper endcap and flexible wire found on motor brushes, just cut off the graphite rod. It can look a bit more professional, and they are low cost from certain sources (hardware store will gladly empty your wallet on these). It is good to remind the new folks around here about it...oh, and in certain other areas where one finds springs, you can often find a pretty decent drop, especially for those fine springs found in switches, where someone used it to carry the current...


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## wquiles (Aug 31, 2006)

NewBie said:


> Another technique is the copper endcap and flexible wire found on motor brushes, just cut off the graphite rod


I am trying, but I can't visualize this. Do you have a photo so that I can "see" what you mean by using these as alternatives?

Thanks in advance,
Will


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## NewBie (Aug 31, 2006)

wquiles said:


> I am trying, but I can't visualize this. Do you have a photo so that I can "see" what you mean by using these as alternatives?
> 
> Thanks in advance,
> Will



Here is one that is for a small motor, for an example. This one here has a brass cap on the end:


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## andrewwynn (Aug 31, 2006)

Newbie's talking about the braided copper wire used for the likes of brushes in motors.. it looks just like solderwick but without the flux so it will probably not soak up solder so bad when you try to solder just the ends... a main issue with using solder wick for this type of mod is that it will become stiff with solder quite a way from the end as you solder. 

The professional look i will have on mine is not using bare wire but a nice clean 16 ga flexible wire that will be soldered right to the end of both sides of the spring.. in-line with the ends of the spring and making a nice short coil down through the spring. 

The spring inside the top of a magswitch that allows the goofy moving of the lamp by the patented quick-focus (useless IMHO).. mechanism is at LEAST 75 miliohms.. thin steel spring.. like 24ga.. it's horrendous.. check out http://prfix.rouse.com to see the fix that drops the resistance to 1/6th.

In a VERY related post.. check out my calculations here

-awr


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## amanichen (Aug 31, 2006)

andrewwynn said:


> amanichen.. incandescent lamp, not LED, but yes using the formula.. but it's accurate... the formulas are extremely accurate for less than 10% voltage difference.


Oops =\


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## andrewwynn (Aug 31, 2006)

update.. 

ok so i used my better power supply that has a far more accurate current readout and my fluke87V to measure the mV drop.. 

pre-fix.. it hovered around 35mohm... post-fix with a 2 1/2" piece (i was quite surprsied it was that long). of 16 ga uber-flexible wire from the KIU kit (scrap that i cut off of doing KIU installs).. ended up.. 1.3 miliohm believe it or not.. a 96% reduction in resistance just from soldering on a piece of wire! one more 'must do' for any maglite! Just plain stunning. 

-awr


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## cnjl3 (Sep 1, 2006)

I had soldered my tailcap springs about a month ago with solder wick,
but since i recvd your "tinker kit" i now have all this spare KIU orange
spare wires so i guess i will have to redo the springs.
I see now that i was supposed to sand the springs which explains why i
had some solder real easily and others were a PITA. 
Now I can mod my previous mods with the outcome of a few more lumens






Thanks for the info!

CYL


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## vortechs (Sep 1, 2006)

I'll have to try the mod, once I figure out where to get the uber flexible wire. 


I did some more experimenting with the 10 Amp tailswitch tail cap from my sub-2D ROP. Even after filing off a bit of the annodizing so that I could be sure I had a good electrical connection for the DDM probes, it still tended to read something like 140-200 ohms (?!?) when the switch was in the ON position. Since that can't be right, now I'm wondering if there are active components in the 10 Amp tailswitch. I don't want to sidetrack this thread but if anyone can point me toward some more resources for info about the tailswitch that I have I would appreciate it sigh: , so much to learn, so little time).


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## NewBie (Sep 1, 2006)

Gavitt Wire and Cable Co. makes some really awesome extremely fine wire which is designed specifically for flexing service.

I've seen some of their stuff that was still in extreme flexing service, from when the item was made, back in the 1950's, in a military maritime environment.

This material is called SuperFlex.

One of the ones I am familiar with has 266 strands of - 44 guage wire in it, which forms like a 20 guage conductor.

"The combination of these characteristics results in an extremely limp and flaccid wire which will provide a high fatigue or flex life in applications subjected to a large number of bends or flexes."

http://www.gavitt.com/PDF/Superflex_Table.pdf

http://www.gavitt.com/superflex.htm


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## frisco (Sep 1, 2006)

You may find some nice wire in small quanity at R/C car shops. Nice flexable, high strand count, high temp, silicon covered wire.

Also braided wire can be found at Slot Car tracks.

These materials have been used for "Jumpers" for a long time.

Another tip is to use flux and silver solder.

frisco


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## andrewwynn (Sep 1, 2006)

cnjl.. yeah use the KIU wire.. my first test with the fat solder wick i still had 15 miliohms.. but to be fair i didn't solder it .. so about 6 of that was probably contact resistance. 1.3mohm with the KIU wire.. what a bonus!

even with sanding.. was still not 'easy' to solder to the steel.. use a LOT of heat

vortech.. fortunately.. you really don't need all that flexible of wire.. just normal stranded wire is fine.. just use 18ga or 16ga.. fatter is completely unnecessary! cuve the wire nicely so it will collapse into the spring nice and you're golden

if you can wire up your light with jumpers or such.. so you can test the switch 'live'.. put your meter on the switch in/out and measure the voltage drop when it is on... with ROP i'm guessing it's like 3A... which means you should have on the order of 30mV drop or less if the switch is doing it's job... i'll point out.. that the FET switch built into the smartpack will be 0.003ohm.. so 3A means 0.009V drop or 9mV.. i'm a very big fan of NOT using mechanical switches for high-current applications.

nice resource for wires, newb, thanks.

I'm going to be sticking with the spare KIU wires.. i have dozens of them.. i get a couple spares from every hotdriver i sell. Now.. as a bonus.. i'm going to include one with each hotdriver so people can get their extra 30-300 Lumen of light! 

-awr


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## BentHeadTX (Sep 1, 2006)

I have some old Fluke test leads laying around so I was wondering if that would be a good wire to use? They are very flexible so maybe it would work? Since I am waiting for Cree XR-E LEDs for my Mag (ship it to AWR for BAM modification) it will give me something to do in the meantime. Am I going in the right direction with old test lead wire?


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## andrewwynn (Sep 1, 2006)

actually that wouldn't be terrible.. it's probably 20 or 22 ga wire, but i use 20 or 22 ga wire in my hotwire design as my sense resistor. it would be 2 or 3 miliohms perhaps but that's a 90+ percent reduction in resistance.

-awr


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## andrewwynn (Sep 14, 2006)

Ok.. I have photos.. see the first post or click here for the album.

-awr


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## eyeeatingfish (Aug 3, 2007)

Ok,
i understand that electricity is lost more through materials with higher resistance and this modification seems rather simple, and makes a lot of sense. What i dont understand is this, does it simply make the light brighter? or are there any downsides? Does it mean the batteries drain quicker or just that less energy is lost in the process?


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## Northern Lights (Aug 3, 2007)

eyeeatingfish said:


> Ok,
> i understand that electricity is lost more through materials with higher resistance and this modification seems rather simple, and makes a lot of sense. What i dont understand is this, does it simply make the light brighter? or are there any downsides? Does it mean the batteries drain quicker or just that less energy is lost in the process?


 
It makes the light brighter and actually since resitance waste energy by turning it to heat it is more efficient and in theory you get a longer run time. This can account for over 100 torch lumens and you can see that difference easily. For a 5761 that is nearly 10%.


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## robm (Aug 3, 2007)

Are you sure you get more runtime?

As I understand it, reducing resistance does indeed reduce the 'wasted' power. But if the total resistance is now lower, then the current is higher (and so the output), but the runtime should be reduced? :thinking:

You would however get more of an output increase than reduction in runtime, as there is less power 'wasted' (I know these 2 cannot really be compared).

Edit: I tried to do some equations, but I am not up to it 

The downside to the resistance fix are the increased risk of overdriving and flashing a bulb due to increased resistance.


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## Northern Lights (Aug 3, 2007)

robm said:


> Are you sure you get more runtime?
> 
> As I understand it, reducing resistance does indeed reduce the 'wasted' power. But if the total resistance is now lower, then the current is higher (and so the output), but the runtime should be reduced? :thinking:
> 
> ...


It is almost a wash, there are so many factors to consider, we could play with the theoretical, lets face it the battery voltages vary with the temperature difference. The big difference is the lumen out put.


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## robm (Aug 3, 2007)

I think you are correct - the output increase is the most significant change/benefit, and the easiest one to see.
I still don't think that the runtime would ever _increase _though :nana: - this is sort of the opposite of adding a switched resistor for a lower output mode, in which case the output is reduced (when the resistor is in place), and the runtime increased, albeit not in a very efficient manner.


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## eyeeatingfish (Aug 4, 2007)

So this seems like an easy hotwire, and ill do it as soon as i can get some wire. What other hotwires are there? Ive heard the switch area adds a lot of resistance but it seems like it would a harder one to do.

Any how to threads about other possibilities?


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## Northern Lights (Aug 4, 2007)

eyeeatingfish said:


> So this seems like an easy hotwire, and ill do it as soon as i can get some wire. What other hotwires are there? Ive heard the switch area adds a lot of resistance but it seems like it would a harder one to do.
> 
> Any how to threads about other possibilities?


http://candlepowerforums.com/vb/showthread.php?t=99710 switches are harder. I like to drill a small hole below the cam screw and attach the ground wire, not make a loop onto the cam. Once soldered I cut a notch in the plastic of the switch below so it fits.


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## Jenova (Dec 7, 2007)

how would some 8g wire go vs the 16g?
less resistance or is thier a certain point where thickness of wire dosent matter

sorry for bring an old thread back up


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## Northern Lights (Dec 7, 2007)

Jenova said:


> how would some 8g wire go vs the 16g?
> less resistance or is thier a certain point where thickness of wire dosent matter
> 
> sorry for bring an old thread back up


Depends on the amps being pulled and yes, after a certain point it is overkill.
You may, in lieu of wire use braid, stripped from coaxial cable material from antena line or other shielded materials. What I like best is de-soldering braid, or wick 3mm-5mm wide works great and is very flexible.
I have also used fine strand multi-strand wire. This mod is very forgiving so do not fret much about it, just do not use too small of a wire for your jumper.


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## Spypro (Dec 13, 2007)

I've made the resistance fix a while ago with a *memory lost here* g wire.
I soldered the wire to the top and to the bottom of the spring (old style mag) and make sure the contacts were ok.
After the mod I looked on different surfaces and the beam looked a little bit whiter. I've done that with my bare eyes but I think this mod is really working when it is done properly.
In other hand, it can be deadly for the bulb if the resistance is too low because the voltage getting to the bulb can be too high.

I have a little question here:
How can I measure the true voltage getting to my 1185 bulb in my [email protected] ? I'm using a bi-pin bulb, AW [email protected] swtich, AW 3x R 18650 and tailcap spring mod. It would help to know the true voltage so I can push the bulb to its maximum. By the way... what is the maximum voltage this bulb (wa1185) can take without flashing or exploding ?

Thanks !


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## mudman cj (Dec 13, 2007)

The sweet spot for hotwires is usually considered to be around 10 hours of life, and from LuxLuthor's excellent efforts to characterize hotwire bulbs, you can see that for the 1185 it is around 11 Volts.

To measure the voltage at the bulb, you can wrap some small gauge teflon wire around each pin before plugging into the socket and then measure the voltage across the wires while operating the light. Be careful not to short the wires. The teflon is to avoid melting the insulation in operation, and might not be necessary for a short test.


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## Spypro (Dec 14, 2007)

Thank you !

I verified the voltage tonight and I'm getting ~11 Volts from the bulb with 3 x AW rechargeable 18650 off the charger (12.6 Volts).
With the recipe I made I think I got a good result in the end. What do you think of the result ?

Now I don't see how I could improve the brightness or lower the resistance.
I already have the AW MagC switch (already low resistance) and the tailcap spring mod.
The only thing I can see is to apply Progold on all contacts...
or building something with a Mag4D, 150w bulb, 12AA... you know what I mean... not pratical but insanely bright for 5 mins.


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## mudman cj (Dec 14, 2007)

Hello again Spypro. I took a look back to August at the beginning of your quest to build your first hotwire, and you have come a long way already. That is an excellent light for your first build. :thumbsup:

I agree that you have reached a point where there is little to gain in continuing to work on that light, so if you want something brighter then a new light is the way to go.

150W is a lot of power, and you are right about the practical limits of such a light, though they can be fun. A slightly more practical light would be an IRC 50W bulb running off of 5 AW C Li-ions for just under 94 Watts of power that would last 30-35 minutes. Or, you could go Nimh and the sky is the limit. Recently, folks like JimmyM, jimjones3630, Raoul_Duke, LuxLuthor, Mac, and others I probably forgot (sorry) have been pushing these high power lights to new limits. They are using 250W bulbs on some of these, and then overdriving them! :devil: If you are considering entering this territory then you should look into what these guys have been up to.

For lights over 100W the runtime is usually quite short, though there are a few builds with more runtime and battery life out there. Some of these use unprotected D Li-ion cells or require large tri-bored hosts to cram in 4/5A or A sized Nimh cells in a triangular arrangement. Few people really find themselves wanting long runtimes with so much light, so a more standard and inexpensive approach is to use AA or 2/3A cells. The head gets hot quick at these power levels, and ceramic insulation is required to be able to use the light for more than 5 minutes at a time without cooling. Some lights like the USL were designed to run out of battery power before this is an issue. 

So, there are a lot of options out there for something brighter than a Mag85, but you have to decide on the most important features of the light you want. 
What is the maximum allowable size or weight? 
What is the minimum acceptable battery life? 
Do you want to take the risks associated with using unprotected D sized Li-ion cells (but only with an overdischarge protection circuit at that)? 
Are you willing to spend extra money to custom bore a host?
etc.

With these sort of answers you will be able to get some better advice.


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## f22shift (Dec 14, 2007)

kai has gold plated springs now


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## Northern Lights (Dec 15, 2007)

f22shift said:


> kai has gold plated springs now


Gold is only 70% the transmission ability of copper. Gold serves the purpose that it never tarnishes so make the best contacts for switches and friction contact like spring to battery. For high perfomance, I would use copper jumpers and solder and keep the friction contact between the frame of the tail cap clean and oxidation free.

Here is a great thread on metal conductivity.
http://candlepowerforums.com/vb/showthread.php?t=151197


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## cat (Dec 15, 2007)

I want to get a few of the kai springs just because it's easier than getting stock ones. (I had a hard time on google and the only 2 places that had them wouldn't do international.) By the time I've modified, there won't be any gold on the contact surfaces anyway. I ground down the 2C spring for 2 AW C cells. It's so short that trying to get a piece of thick wire to curve around and stay in place, and solder it was a pia. Eventually I got it done with de-soldering braid.


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## Northern Lights (Dec 15, 2007)

cat said:


> I want to get a few of the kai springs just because it's easier than getting stock ones. (I had a hard time on google and the only 2 places that had them wouldn't do international.) By the time I've modified, there won't be any gold on the contact surfaces anyway. I ground down the 2C spring for 2 AW C cells. It's so short that trying to get a piece of thick wire to curve around and stay in place, and solder it was a pia. Eventually I got it done with de-soldering braid.


 
Here is the solution to your problem. You can build the 2C without any extra spacer in the tube and this solves the resistance and spring problmem.

click this link for the story: 2C Mag Tail Cap mod for AW's "C" cells 

Here is a similiar one used in another application.


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## TOOCOOL (Dec 15, 2007)

Northern Lights said:


> Gold is only 70% the transmission ability of copper. Gold serves the purpose that it never tarnishes so make the best contacts for switches and friction contact like spring to battery. For high perfomance, I would use copper jumpers and solder and keep the friction contact between the frame of the tail cap clean and oxidation free.



They are copper plated over steel then gold plated


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## Northern Lights (Dec 15, 2007)

TOOCOOL said:


> They are copper plated over steel then gold plated


That sounds ideal, best yet. My mods most of the time usually need cut down springs or use isolated terminals so I can put in fuses and NTCs, but I bet I could find a use for one or two plain springs; I will look into it! Thanks.


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## jimjones3630 (Dec 16, 2007)

One more me two. Have used thick 8 or 10 ga copper jumper between bottom of tailcap spring and top. Then went to copper braid from a car battery ground cable. Thick stuff and noticed more lumen output.

Lastly, tried Northern Lights style tailcap spring substitute which is very effective and produces noticiable to the eye lumen gain. Working to convert all my tailcap springs to NL's design for ease of maintainence and decreased resistance.


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## Pyros (Dec 18, 2007)

NL, I love your solution, but where do you get your copper braid? I've asked at the local hardware store and searched online, but without much success.

--Pyros



Northern Lights said:


>


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## Northern Lights (Dec 18, 2007)

Pyros said:


> NL, I love your solution, but where do you get your copper braid? I've asked at the local hardware store and searched online, but without much success.
> 
> --Pyros


Sorry, just presumed, like many, that it was obvious.
The best braid to use for limpness and abililty to withstand flex is none other than:
De-soldering wick, Radio Shack, any electronics supply even Dealextreme.com has many lengths and widths of the stuff, 3mm is a good width for about everything.
e.g.
http://www.dealextreme.com/search.dx/search.goot
http://www.radioshack.com/search/in...soldering braid&origkw=desoldering braid&sr=1
even Amazon.com has it.

I like techspray.com brand; hint: they offer free samples!
http://www.techspray.com/pindex.htm#1800

google: *desoldering braid and desoldering wick*

Unless you can solder without ever using too much solder, or you never make mistakes, then this stuff is really great to clean up and make a professional job with too. 

In a pinch I have stripped the braid out of coaxial antena cable or any shielded line. 
I prefer non-flux wick but mostly pre-fluxed is available, if that is the case you do not want that melting or fuming, especially if you used it to wire up the switch to fix the ground resistance. If that is the case, you can use a little solvent, e.g. laquer thinner, paint thinner, gasoline, carb cleaner, etc. to de-flux a portion of the braid before use.


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## Pyros (Dec 18, 2007)

Northern Lights said:


> Sorry, just presumed, like many, that it was obvious.


 
Thanks NL. I'm still on the steep end of the learning curve, and was asking/searching for "copper braid" instead of "desoldering wick." I'm going to try this on my Mag64, which still has too much internal resistance. (My new Mag623 is working like a champ though, thanks in part to Lux's battery pack with integrated tailspring!)

My friends think I'm completely nuts, but this Mag modding stuff is too much fun. Thanks to all you guys for sharing your knowledge.


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## Northern Lights (Dec 18, 2007)

We are all "nuts" I see that you are new here, welcome, not that I am anything to, about or from CPF but I am glad CPF is here for my fun. You are among those like yourself, friends, and every opinion and contribution I think adds to the forum.


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## Joshatdot (Dec 19, 2007)

How is the OP getting 45miliohms? I just checked my [email protected] 4D spring and was getting 0.0~0.1 ohms.

NM my DMM is a crappy Craftsman and only goes to 0.0 ohms. Does 0.0x or 0.00x ohms make that much difference?


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## cat (Dec 19, 2007)

I had seen the hose+braid, but I thought the spring modifed without the de-anodising would look neater (yeah, I know you can't see it, but...). The problem was that the spring is about 7mm shorter than standard and the wire I was using was about 8 or 10AWG - quite flexible but not when it's so short. I might have been able to hold it in place with small vise-grips but I thought my little 14W soldering iron wouldn't be able to cope, with that much heat-sink. (I need a gas iron.) 

Anyway, I'm _*still*_ waiting for the PO to come up with my reflector  so I can try it. 

Can you _get_ copper nuts? I've got a good place for ss fasteners, and I got some brass machine screws and nuts etc there when I went to get M3 hex heads to use instead of the Phillips on the socket, but nothing copper. The only copper stuff I've seen is plumbing stuff. Automotive starters etc use brass. 

The copper plating used on the Kai springs ..I doubt that it's as good for reducing resistance as a copper jumper; it's thin and you've still got the long length of the spring.


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