3 x aaa to l-iion ?

So I have half a dozen cheap Chinese aaa lights that I think were advertised as 3 watt 160 lumen when I bought them several years ago.
They are quite floody with a hot spot with a lot of spill.
I can get an unprotected 18650 in them just length wise (diameter is fine as the tube is 23mm id) but I can only catch about one whole thread when putting the tail cap on.
With an 18650 the run time is massively increased over 3 aaa”s alkalines & the light is brighter.
If I could get a short extension tube I could use either18650”s with a sleeve or even 22650 protected cells.
The present aaa carrier is 55mm long overall so an extension tube of about 10-12mm long should do.
od/id of the tube & tail cap thread is 24.5mm.
Any thoughts ?

You could use 18500 in there instead of 18650. The capacity is a lot less, but still better than 3XAAA and the output should still be very good as well, if you get decent cells.

Maybe a 18500

Rather than going with a new tube, try using an 18350 with a short spacer to fill in. Obviously it wont have as much capacity, but it might still perform better than 3x AAA?

Yes I had already thought of an 18500 with a spacer & sleeve but if I could get a short extension I could run 18650/22650, no need for a sleeve & better run time compared to 3 aaa.
22650 would be ideal diameter wise.

I don’t know of any 22650 cells. Where do you get those? They’d be useful to me, too!

As for getting a short extension, I don’t know how you’d do that. It might not even be worth what it would cost. The 18500 will still give you a LOT longer run time than the 3XAAA cells. You could try modding the head or the tailcap to get more internal depth for the 18650 to fit in. Is there any room for that?

you can find 22650 http://www.batteryspace.com/linimnco-rechargeable-22650-cell-3-7v-2500-mah-9wh-3-75a-rated—-un38-3-passed.aspx
about as rare as hen’s teeth. Most 22650’s are LiFePO4 Batteries.

I say it’s not worth it. An extension tube will need the right ends and thread pitch and diameter. So very unlikely to find something random that’ll be the right size.

And tbh the gains are probably minimal for the cost. 18500 will work, but if any of the lights are 4xAAA then it’ll be dimmer most likely not brighter. And if runtime is a real issue, just use a different torch.

Yes 22650”s are very rare I was just thinking out loud really as the id of the tube is 23mm.
I can just get a flat top unprotected 18650 in but would prefer to run a protected as the light has no low voltage protection so that would be a couple of mm longer.
The only thing I could do would be to shorten the tail spring as the head is fixed & has a little nub.
Even if I took a few mm off the spring I couldn”t see that doing anything as the spring is locked up with I turn with a non protected flat top.
Maybe I am wasting my time it is just that brightness was noticeably better with an 18650 & the light didn”t get hot.

They are 3 x aaa.
I bought them about 5 years ago on a deal for iirc £10 for 6 with holsters delivered, but was so disappointed with them I threw them in a box in the shed.
I found them a couple of days ago & started playing about with them hence the questions.
Maybe I will just bin them.

Are there springs you could remove to gain a little space? Removing 1 large spring should easily get you from 1 thread to 2 threads of engagement, maybe more…

Well success :slight_smile:
I halved the length of the tail cap spring which seems to have given me about a mm & found some bare 26f laptop pulls that were slightly shorter than the cells I had tried previously & I can now get the tail cap just up to the “o” ring.
There is no way I will be able to get protected cells to fit so I will have to watch the voltages but the lights are now considerably brighter than with the 3 aaa”s & should have much longer run times so I will put a few in drawers around the house just in case & 1 in the car & 1 in the camper van once I have cut the springs down on the others.
Thanks very much for the help.

If you’ll be careful when tightening the tailcap, you can get rid of the springs completely and replace with just a little solder blob or maybe a nub of copper/brass just enough to make contact with the cell.

I had to leave some spring as it protrudes through a hole in a plastic disc in the tail cap & if I cut the spring out completely there would be no contact.
I think that the battery is now compressing the spring down flush with this plastic disc so no more gains in length are achievable to allow me to run a longer protected cell but I have plenty of lap top pulls that I can use in these lights now & now at least they are usable.

23mm adapter is quite standard for 3xAAA. Something like this?

http://www.ebay.com/itm/Extension-Ring-Tube-Joint-Adapter-Rechargeable-for-Bright-Flashlight-18650-MTC-/351344108680

Thanks that may be just the job to allow me to run protected cells.
I have just found them on ebay uk for £0.99 each delivered or $1.44 so will hold off cutting the springs on the other 5 lights & see if these extension tubes work first.

Remove the plastic disk and glue the switch in place from the sides with arctic alumina. That way you can completely remove the tailcap spring and replace it with a solder blob.

i have pulled the retainer from the tailcap and cut the part that holds the switch off.i reinstall that and fold the tab on the back of the switch to make better contact.gains about 5mm.
just did that to a 3aaa heavy built 9led that has a shrouded switch.so it can tailstand.
this has a threaded ring to retain the board so it offers a bit of heatsinking too.
running only 8 as the center has no path to the ring.so far its fine!