Modding 3AAA FL to take 18650?

Hello.

Might it be possible to mod a 3xAAA FL (lenth wise) to accept an 18650 (protected or not) li-ion?

Without adding a tube extension.

ex.

http://www.dealextreme.com/details.dx/sku.3405

Will be modding the led as well.

I can't comment on this particular light, but in general, 3xAAA battery carriers are similar in size to an 18500, usually a little shorter. I doubt that you could fit an 18650 in there. The 18500 will still give you considerably better capacity than 3xAAA, so it may be worth it if you can make it fit.

The 65 in 18650 is the length of the battery in mm. My 3xAAA battery carrier is 55 to 60 mm depending on how compressed the spring is. It seems like an 18650 wouldn't fit.

It would probably be easy to use a RCR123 with a girdle and a spacer.

Measuring an AAA-cell, I find it to be 10,2 mm in diameter.
The 18650 and 18500 cells are 18 mm in diameter.
So the problem is not the length, but the diameter of the cells!
None of the Li-ion-cells mentioned will fit in this body.

LightScene said:

It would probably be easy to use a RCR123 with a girdle and a spacer.

Click to expand...

I've done exactly that, with good results. Pennies make good spacers, as you can add or subtract them to get the spring tension just right.

labrat said:

So the problem is not the length, but the diameter of the cells!
None of the Li-ion-cells mentioned will fit in this body.

Click to expand...

He's talking about a light that uses 3 AAAs inside of a cylindrical battery carrier. These carriers are generally somewhere between an 18500 and a C cell in size.

I've modded a different 3 x AAA light to use a protected 18650. I had to remove the switch assembly and sand down its retainer. Not a big deal, and the battery fits perfectly now. Not sure about this light, but it looks like it's worth a shot.

It just depends on the light and how it's designed - for example, the fact that it uses a spring-loaded AAA battery carrier increases the odds that you will be able to mod the light to fit an 18650 (some AAA carrier lights have less 'play' for the carrier than others). I'd say that there's probably about a 50/50 chance that you'll be able to get an 18650 in there after removing excess parts in the tailcap. This looks very similar dimensionally to the 'Ristoft' light that is a popular light to mod with a Cree and 18650, I've done a couple of them myself and it's not too tough if you remove everything except the tailcap switch. I've also modded another light that was somewhat like this to use an 18650, but that light required me to lathe the inside of the aluminum tailcap to fit the 18650, works great now though.

From looking at that light, it looks like a very good candidate to mod with a Cree, as the pill looks very good in size and would probably do a better job of dissapating heat than some pills would.

If you DO buy this light, let us know how it turns out and if you are able to get an 18650 in it. An unprotected 18650 will make things a little easier since it's probably about 1.5-2mm shorter.

Hello.

Actualy i bought 2 a while back.

I spent an hour on it today.

Width wise it will require a bit of shimming for the protected 18650 . The original 3xAAA bracket being 22mm in diametre.

Now as for the lenth. I had some problems. The original tail cap switch spring has to be removed in order to fit the 18650.

However there was enough leeway to have a very short switch spring.

The problem came when you tightened the tail cap. The switch is too long.

I might get a 1/3 thread on, but that's all.

This would go better with 18600's Still 5mm is not much more thread space.

The only way (safe) to get this to work is to move the + pole mount further forward.

I was hoping that this would work as it would provide two battery type options with no mods and an initial low cost FL that you can spend the money on the more important mods.

I took another of my 3xAAA fl's that had a longer tube and more space between the bracket and the cap. The 18650 worked perfectly.

As you said it's 50/50 that you will find a 3xAAA FL that will have sufficient tube lenth to support 18650 li-ions.

As this is the first time i've disassenbled one of these mdxl 5watt luxeons. I can't help you on as to how ot forward that + pole mount.

I' went local hardware store to find some threaded copper or aluminum pipe to make a 1/2" extension tube so far it works. Needs paint

I'm modding it to take a spare cree i have. Wish me luck.

Thanks.

Northernflame said:

Hello.

Width wise it will require a bit of shimming for the protected 18650 . The original 3xAAA bracket being 22mm in diametre.

Now as for the lenth. I had some problems. The original tail cap switch spring has to be removed in order to fit the 18650.

However there was enough leeway to have a very short switch spring.

The problem came when you tightened the tail cap. The switch is too long.

I might get a 1/3 thread on, but that's all.

This would go better with 18600's Still 5mm is not much more thread space.

The only way (safe) to get this to work is to move the + pole mount further forward.

I was hoping that this would work as it would provide two battery type options with no mods and an initial low cost FL that you can spend the money on the more important mods.

I took another of my 3xAAA fl's that had a longer tube and more space between the bracket and the cap. The 18650 worked perfectly.

As you said it's 50/50 that you will find a 3xAAA FL that will have sufficient tube lenth to support 18650 li-ions.

As this is the first time i've disassenbled one of these mdxl 5watt luxeons. I can't help you on as to how ot forward that + pole mount.

I' went local hardware store to find some threaded copper or aluminum pipe to make a 1/2" extension tube so far it works. Needs paint

I'm modding it to take a spare cree i have. Wish me luck.

Thanks.

Click to expand...

Thanks for the detailed response. Regarding width, yeah you'll just need to add a piece of thin 'cardboard', a thin tube, etc around the 18650 to center it. As far as length, if the pill is hollow then maybe you can move the contact forward as you mention, though then any option of adding regulation is probably out of the question - direct driving a Cree with an 18650 is ok if it's heatsinked decently (put some thermal paste under the star for one thing as that really helps) and not run for very long periods of time (especially when the 18650 is fully charged around 4Volts+). Another option may be to unthread the pill part way to give more room inside the battery tube, you can use an o-ring or better yet would be some kind of metal ring to fill that gap under the pill if necessary. You also didn't mention if the 18650 you have is protected or not, if it's protected then an uprotected 18650 may allow you to thread the tailcap much further as even 2mm can make a fair amount of difference in the play (I'm not that big on protected cells, my charger protects from overcharging and I know that the battery is at a low enough voltage to quit using when the light becomes noticeably dimmed). I don't know what the tailcap switch is like in that light, but if it's anything like most of the other lights like that that I have, there will be either a plastic or metal piece holding the actual switch assembly, that can be removed and just leave the switch itself and that will gain you a few mm (you may need to glue or epoxy the switch into the tailcap if you remove the surrounding housing from it as it will move around freely at that point). Technically I can still use a AAA carrier if I want, I'll just need a long spring in the tailcap. As far as getting out the positive pole mount, you can probably just press it out from behind the LED star, that's how I've done it on my lights.

If you want more detail on some of the things I'm speaking about, do a search for 'Ristoft', you'll find a long thread with a lot of photos on how they are modded and it should be pretty similar with modding this light in most regards. Good luck, photos of the finished product would also be good if you have a camera.