# Battery sleeve and tailcap spring for 18650s in a 3C Maglite?



## StorminMatt (Nov 22, 2012)

I've never really messed with li-ion batteries. But I saw a charger by Tenergy that came with two 18650s for a fairly reasonable price last night at Fry's. And I figured what the heck? The first thing that came to mind was my 3C Maglite. After all, two 18650s are roughly the same length as three C cells. And I figured I could use this to run either the 6C Xenon bulb or the 3854L. This would give me a good 'bright enough to see well, but not overly bright' incandescent light for those situations where I want to take a walk at night, but am more in the mood for an incandescent. But I have a couple of issues I need to resolve before this can be a good, 'everyday use' light.

First of all, I need some kind of sleeve to make those 18650s fit better in the 3C tube. I tried .75 inch PVD pipe. But although the battery fits inside it well, it is just a tad too big to fit inside the tube of the flashlight. In the end, I got the batteries in the light by wrapping them in newspaper. But I would certainly like a more permanent solution than that. Is there something that someone has found that works well for holding 18650s in a C cell Maglite?

The other thing I would like to change (if anything is available) is the spring in the tailcap. It actually puts slightly less pressure on the batteries than C cells. But it still gets the job done in terms of holding the batteries and conducting a current. On the other hand, the end of the coil is about the same diameter as the exposed metal area on the bottom of the battery. So I'm not sure what kind of contact it will make in the long run. Are there any good solutions available here for a spring with a smaller diameter coil at the end? Or is bending the spring or making some sort of spacer/plate the only way I'm going to be able to get this to work?


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## jcvjcvjcvjcv (Nov 22, 2012)

Get a Delrin rod with the correct outer diameter and drill a hole in it.

But does it fit length wise? 18650's are 15-17 mm's longer compared to C cells.


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## StorminMatt (Nov 22, 2012)

jcvjcvjcvjcv said:


> Get a Delrin rod with the correct outer diameter and drill a hole in it.
> 
> But does it fit length wise? 18650's are 15-17 mm's longer compared to C cells.



Only thing is, I don't have a drill press. It's going to be HARD to get this accurate by eyeballing it! I don't know if it would just be easier to sand down the PVC pipe.

Lengthwise, the fit is actually REALLY good. Two 18650s are just a little shorter than three C batteries. The spring actually contacts them, but does not put NEARLY as much tension on them as on C batteries (which is probably a good thing).

All of this brings up a point. I NEVER understood why NOBODY mods the 3C light. The 18650s fit SO much better in this light than in a 2D. Not to mention that it is only a fraction of an inch longer. And it just fits ALOT better in your hands.


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## jcvjcvjcvjcv (Nov 22, 2012)

????

A 3C is almost 2 inches longer compared to a 2C. That's quite a bit


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## StorminMatt (Nov 22, 2012)

jcvjcvjcvjcv said:


> ????
> 
> A 3C is almost 2 inches longer compared to a 2C. That's quite a bit



I was comparing the 3C with the *2D*. The reason I drew this particular comparison is that lots of people like to mod the 2D compared to the 3C. Yet, the 3C is just a little bit longer, can better fit lots of battery options, and fis really nicely in your hand.


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## Justin Case (Nov 22, 2012)

Post deleted.


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## StorminMatt (Nov 23, 2012)

I think I may have found the ultimate solution for the C adaptor. Specifically, Ultrafire makes a tube for their UF-5C light that allows 2x18650 rather than 5xC. And it comes with spacer tubes to fit a C size bore. True, the diameter of the UF-5C might be a little bigger, preventing the use of these adaptors. But it's only $9. And the UF-5C itself is only $34 more. So even if it doesn't work, I can get a whole other light out of the deal!


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## yellow (Nov 23, 2012)

why mod any C (or D) cell light to 18650?
:thinking:
wasted space all around.

If I were to "mod" a *C* celled light, I would try to get *C* sized Li-Ions
(and the same with Ds)
... and use my 18650s in lights built for them (smaller diameter - better to pocket)


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## StorminMatt (Nov 23, 2012)

yellow said:


> why mod any C (or D) cell light to 18650?
> :thinking:
> wasted space all around.
> 
> ...



The issue here is convenience and availability. 18650s are widely available in stores. But if you want to go with a 25500 (C), 26650, or 32600 (D), you generally have to order online. Quality can also become an issue, as you will be dealing with more 'off brands'.


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## yellow (Nov 25, 2012)

no,
the issue is an unnecessary big light because of toting around more volume in air (in the sleeve) than the nonfitting cells have in size


... im a backpacking guy and therefore small packing size is ...


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## jcvjcvjcvjcv (Nov 25, 2012)

Not everyone is a backpacker. 

Maglites are relatively cheap and well-available. 

Lion cells bigger than 18650 are not. Especially quality cells.


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## Admiralgrey (Nov 27, 2012)

I think the popularity of 2D mods is mostly a result of people already having them from their pre-flashoholic days. They're dirt cheap and available everywhere. That and the faction of people who would rather use a small herd of NiMH's.

The C sizes on the other hand are not only more ergonomic, but can make the most efficient use of space. Break hones are available for 10$ shipped on amazon, then you can slide in some 26650's.
That said I'm getting a bit concerned about the future availability of 26650's. 18650's are encroaching on currently available 26650's in terms of capacity, and for much less weight.
Given the vast improvements in capacity and weight over their full payload of alkileaks/NiMH I'm happy to call it a day using 18650's in C's.


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