# Convert HDS/Novatac 2X123 to 18650 for $1



## Hogokansatsukan (Sep 14, 2008)

*EDIT: This post is 11 years old as of this edit and DOES NOT apply to any subsequent HDS lights, specifically the Executive/Rotary models or any other. ONLY the old Basic/Ultimate and may not even apply to ALL of those older models.*

So, a thread in here got me thinking about the electrical pathways in the HDS and Novatac, and once I start thinking, well, trouble is bound to follow.
Gunga told me this was gone over before, but for the life of me, I could not find the thread. So, here it is, maybe invented again, but what the heck.
This is how to take your 2Xcr123 battery tube for a HDS (yes you can use 2 cr123 in it) or the same tube that many use a 17670 in the Novatac (NO! You can't use 2 cr123 batteries in your NT without very bad things happening... how bad?... VERY BAD!!! Not that I've done it and my nickname is "Lefty").
This will focus on doing it for the Novatac.
First, you need the tube. Go to Lighthound and order one if you don't have one already. While ordering, pick up a couple rare earth magnets to use as nipples on your 18650 batteries if they don't already have nipples (not sure why some of them don't, but then chicken breasts don't have them either... go figure.)

Next, go to Ace Hardware or your local hobby store and buy this:






While your there, go the flashlight section and laugh at the crappo lights.
Go home. Have a beer (don't drink and drive... drink. Beer is cheaper than gas).
Now, take that tube and if you have anything attached to it like a head or tail, take them off, and take the spring out. Should look like this if you have done it correctly. If it doesn't, have another beer and try again.






Notice how it's all nice and smooth inside without that spring in there clogging it up? Also notice that the tube has rounded ends and the NT tube has that cool cutaway. This is important. When you put the NT tube on the head or tail, the ledge goes over the retaining ring (that outer most ring that sticks up inside the head and tail).




See that outer ring? It's not just for holding in the pill. This is the main "negative" for the flashlight. See that big flat ring inside that? That is where the spring needs to make contact (HEY STUPID! YOU SAID TAKE THE SPRING OUT!) Yes, I did. Have another beer and just relax.
You see, when you screw that rounded end tube down onto a NT light, the inside edges of the retaining ring are exposed to the spring (if it is in the tube). This is important to know as you don't want our newly made item touching the retaining ring (I'm not responsible for blown off fingers... ok, that won't happen but your switch won't work if it touches.)




Now, have another beer, then carefully bend about 1/2 inch of the flat bar you just spent a days pay on. Bend it just a hair. If you bent it too much, stop drinking, sober up, and try again.
If you insert the battery in the tube (no head or tail on the tube) and push the brass bar into the tube, looking at the bottom, it should look like this:










Notice how the end of the brass bar is not flush against the side wall of the tube. Yes, Grasshopper. This is correct.
Take it all out now.
Now, screw the tailcap on the tube and put that 18650 battery in there. Insert the brass bar with the end you bent first and push it down into the battery tube until it makes it past the rubber HELTPP (the gray rubber spacer). If it catches on this, you bent it too much and need to try again. It should be bent just enough so that it will be out of the way of the retaining ring in the tailcap. No more.
If done correctly you should have something that looks like this:




Now, mark your brass bar about 1/8 of an inch from the edge of the tube. Make sure the bar is fully againt the tail cap. Cut it off here. Now take the bar out and bend the top of the bar over so that it looks like this:




Take out your 18650 and hold the bar right up along side it with the newly bent end on the positive side of the battery. Make sure that the brass bar will not touch the positive contact on the battery. If it does, trim it.
Here is a pic from the top with the battery and bar inserted in the tube.




The nipple on your battery MUST be slightly higher than the brass bar.
Now screw the head on your light. It works!!! Or not.
If not, here is the trouble shooting section:

1. Light fails to come on at all (1 second dim light): YOUR NIPPLE AINT HIGHER THAN THE BRASS BAR. Fix it. (Twisting it in your fingers will not work for this.)
2. Light comes on for 1 second, turns off. Switch does not work: Your brass bar is too short and not touching both the head and tail. Good thing the brass bar is long enough to make two or three of these things. Try again but be easier on the cutting this time. Maybe less beer as well.
3. Light comes on bright and stays on. Your bar is making contact with the retaining ring in the head or tail. Bend the tail section a tad more. Check and make sure that the head section of the brass bar has it's top most point away from retaining ring.
4. Light starts to smoke, vent gasses and explodes in my hand: Brass bar was making contact with the positive terminal on the battery. Call 911 and get medical attention. Buy new NT, brass bar, and battery tube and try again when your hand grows back, and remember, I am not responsible for this. Beer will help the pain.

I've been using mine for about 4 days now and have had zero issues. I'm constantly taking it apart and putting it back together and it works every time.

Happy playing.


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## Hogokansatsukan (Sep 14, 2008)

il'l eddit me speling latter. Im tyrd.
Wers my beer?:drunk:


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## lumafist (Sep 14, 2008)

Thanks.............

You just made me smile on this morning.....!
(yes, morning here...)



Cheers...!


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## DM51 (Sep 15, 2008)

That is an excellent "how to" post, Dan, and very entertaining too - LOL!

I'll move it to Homemade & Modified, and leave a permanent redirect here in LED Flashlights.


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## Raoul_Duke (Sep 15, 2008)

The 18650 magnets comment made me LMAO :naughty::twothumbs:duh2:


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## tx101 (Sep 15, 2008)

> if they don't already have nipples (not sure why some of them don't, but then chicken breasts don't have them either... go figure.)



ROFL :laughing::laughing::laughing:

I never notice that, and I handle chicken breasts every day :naughty:


Very nice pic tutorial ..... worthy of a sticky ???

Thanks


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## Tessaiga (Sep 15, 2008)

tx101 said:


> I never notice that, and I handle chicken breasts every day :naughty:


 
What sort of a sicko perv are you!!! Now get your filthy hands off those chicken breasts and find yourself some real ones...


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## LukeA (Sep 15, 2008)

Watch out about using this with nub-less cells. That magnet could shift and cause a short.


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## Hogokansatsukan (Sep 15, 2008)

LukeA said:


> Watch out about using this with nub-less cells. That magnet could shift and cause a short.


 
I was trying to make this happen (I poke big dogs with sticks, throw rocks at rattlesnakes, and read Playboy with my wife around as well). I could not get the rare earth magnet, I'll just call it a "nipple" to shift. I banged the light around, slamming it on the floor, table, a board outside when my wife kicked me out of the house for making too much noise when the kids were sleeping. Never got that magnet to shift. (I have been bitten by large dogs, rattlesnakes, and clubbed with a rolling pin, so I know I must be doing something right).


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## Burgess (Jan 8, 2009)

hey Hogo --


That's a truly wonderful post !


Well-written, informative, concise, and even humorous. 


Plus, it's well-illustrated with fine photographs, to boot.



You certainly deserve an AttaBoy for yer' efforts !

:twothumbs

:wow::goodjob::kewlpics:
_


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## divine (Jan 10, 2009)

That works really well. I was going to bench my 17670 tubes because 1500mAh isn't much more than 1300mAh. Good thing I came across this thread.

Thank you.

Oh, and you got ripped off... Ace charged me 59 cents for mine.


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## Bullzeyebill (Jan 10, 2009)

Seems to be that using the flat bar spring would reduce resistance compared to the stock tube spring. Big time.

Bill


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## tebore (Jan 10, 2009)

Bullzeyebill said:


> Seems to be that using the flat bar spring would reduce resistance compared to the stock tube spring. Big time.
> 
> Bill



It wouldn't matter. The current is carried by the body. The tube spring is only used for signaling.


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## Bullzeyebill (Jan 10, 2009)

tebore said:


> It wouldn't matter. The current is carried by the body. The tube spring is only used for signaling.




OK, thanks. So the flat bar takes place of coiled spring for signaling. 

Bill


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## Hondo (Jan 10, 2009)

Got mine working great, thanks Hogo!

But, I would like to add a couple of bits of info for folks doing this. First, and VERY importantly:

If you are a cheapskate like me and are using batteries from a laptop pack, be VERY sure that you grab a cell that has the shrink wrap around the bottom end of the battery. I had two types right on my bench that the shrink stopped just short of the neg. end of the battery case, and trust me, it does not work when this can contact the brass strip. Not sure why, but this caused my 120P to do a factory reset, and start having problems with the lowest few modes (pretty much dark). I did what fixed it the first time (had this problem when it was new), which is swap out the emitter, and I am good again, but hopefully I will save someone else the hard lesson.

Second, and on a much more positive note, if you do end up a bit short on the brass strip, just add a blob of solder at the bend on the top end, much easier than starting over, and won't cause wear on your light engine board.

Also, and this should be kind of obvious, but if you have one of the very late Novatacs with the spring on the head end, it is not necessary to have the nipple of the battery above the brass bar.

I got raked over the coals at the True Value hardware on my way home from work, paid $1.39 for the brass strip. Lucky I can get three of these things from it, or I would really feel cheated!


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## nanotech17 (Jan 13, 2009)

i just got the tube from Lighthound today had to cut the spring about 5 rounds because it's too long,finally it's working but still intermittent issue once battery change take place,will have to find that flat brass bar.


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## nanotech17 (Jan 15, 2009)

got the brass bar from an old unused flashlight and it is much brighter compare it using the coil spring.

KL6 U2SVOH 1A 2xAW 17500- 2 feet





novatac u2svoh 1 x AW 18650 + UCL


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## Hondo (Jan 16, 2009)

nanotech17, I am puzzled by both of your last comments. I don't understand why you would need to cut the spring, it is nowhere close to being coil-to-coil, so it should have plenty of room to compress as the light is assembled.

As for being brighter with the brass bar mod, it should not be. The bar, or spring, only provides momentary signals to the light engine for what mode to go into. The main power path to the engine, and LED, is through the battery tube itself, so the amount of impedance in the signal path should not be a factor for brightness. :shrug: I am not saying that you may not be seeing a brightness change, mind you, just that I can not, but would like to, understand how that could be the result of which type of signal connector you are using (spring or bar).


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## nanotech17 (Jan 16, 2009)

hi hondo, to my eye it's brighter vs the coil spring but your point is correct as well,i don't know how to explain it rationally.


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## tebore (Jan 16, 2009)

nanotech17 said:


> hi hondo, to my eye it's brighter vs the coil spring but your point is correct as well,i don't know how to explain it rationally.



Possibly because there's no explaining. In order for your eye to notice it being brighter it'd have to be ~50% increase in light output. Again the brass bar used in the mod is only for the signal, it carries little to no current under operation. 

It's gotta be the the same idea as your car performs better after a wash. 

You could set a camera to full manual and take pictures to prove it to yourself.


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## John_Galt (Jan 8, 2010)

Very cool! I just happened to purchase an old HDS B42XR and 2x123 battery tube! I'm glad I found this!


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## ma_sha1 (Jan 10, 2010)

it's really a $10 mod, $1 bar, 3x $3 beer


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## souptree (Jan 10, 2010)

Very entertaining post. Great job. :thumbsup:


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## John_Galt (Jan 11, 2010)

ma_sha1 said:


> it's really a $10 mod, $1 bar, 3x $3 beer



I don't have to worry about that last $9, doncha know. LOL:laughing:

Some of my school-mates might have to, but then they don't tend to buy $3/can beer...


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## Kid9P (Mar 4, 2010)

Ok, I went to 3 Home Depot's and 1 Michael's and I still can't find
that little metal bar 

If anyone has one to spare, I'd glady buy it from you !!
*Just shoot me a PM*

Thanks!

Ray


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## Hondo (Mar 6, 2010)

Kid9P, try the hardware stores, like ACE, True Value etc., that is where I got mine.


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## Derek Dean (Apr 25, 2012)

I know it's kind of an old thread, but I had put my NovaTac 120P aside in favor of a ZL SC600 as my EDC, mainly because I love having hours and hours of light provided by the 18650, but now, after spending a whopping $8 to convert it to 18650 ($6 for the tube from Lighthound including shipping + $2 for the brass piece from ACE), I've got my NovaTac 120P back as my main light again (also sporting a new Nichia HiCRI 219 4500k LED). 

Thanks, Hogokansatsukan*, *for taking the time to document and share this EASY mod. Highly recommended!


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## Kestrel (Apr 25, 2012)

Derek Dean said:


> Thanks, Hogokansatsukan*, *for taking the time to document and share this EASY mod. Highly recommended!


Haven't seen Hogo around much recently. Probably just too busy to be posting much these days, he does have a great sense of humor though.
Best wishes wherever you are, :wave:


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## Lucky Duck (Sep 16, 2013)

Thanks, Hogokansatsukan*, *for taking the time to document and share this EASY mod. Highly recommended![/QUOTE]

+1,000! Love it, & indeed easy! ( Cheap too!)


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## cynical (Jul 6, 2021)

Wow, I REALLY hate necroposts, but I have to give credit where credit is due. Thanks to Hogokansatsukan for this great post! Fortunately the pics are still up. I had bought the extended tube for my Novatac SP120 years ago, I think from Lighthound. I could never get it to work, and then I lost the spring. For some reason I hung on to the tube. I decided to invest in the brass strip, which I couldn't find online for less than $8. But now I'm using the tube, and with 18650s! Woohoo!!


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