my mods for a three C CELL Backup light from eneloops to 18650's.

robdataff

Newly Enlightened
Joined
Apr 7, 2014
Messages
6
Hey guys.

Been lurking around the forums for a while thought i'd finally register. anyways here is what i managed to do to my meager collection of dive torches.

I travel a lot, and tend to have to buy lots of crappy locally produced c cells for my torches. I carry 2 with me - a Brinyte DIV 01 (aka a Dris1000) and a UK SL3. Both use 3 cells. The DIV01 is a new buy for me. my old 'primary' was a magic shine 810. This worked pretty well.... for a while. it had a terrible habit of fizzing along its length. its nice to see it slowly dissolving as i swam. eventually the LED burnt - so i replaced the LED, then it got very tempermental if it wanted to work for longer than 3 mins at a time...... time to go!

so the long and short - i now have two torches running of 3 c cells. on my sl3 i used AA to C cell adaptors. cheap plastic things that meant i could use rechargable AA's. the Sl3 still gave me a decent brightness level, and well over three hours of run. great. tried the same in the DIV01, managed to get about a 40min run time before it got super dim. this is with some brand new eneloops as well. (cycled a few times obviously) I did use standard 3rd gen eneloops, so i could have gonna for the XXX version, which would have given me maybe an hour run. not really enough, as i teach a lot. its great saying to the students that you do a 50min max dive, not so good when the boat cant find you at an hour and ten. rechargable c cells need a big charger, and are fairly hard to find in decent capacity. and they seem pretty expensive.

so.... i had an old laptop battery, broke it open, got 6 sony cells, all registering over 4 volts. charged them with my old magicshine chrger. all terminated between 4.17 and 4.19 volts. cool. i did charge them outside in an old plant pot though :naughty:.

2 18650's in series dump out 8.4 volts max. chucking them in a 4.5v application tends to result in boomy/smoky/flamy shenanigans. using one of my 18650's with big spacer would work, but really wouldnt be much improvement on just using 3 eneloops. so i needed to use them in parallel, but using a series style physical arrangment - i.e paralleled electrically, end to end in length. There dont seem to be any threads on how to do this? my google fu is weak.

so parallel in a long line....

so thats what i did. i scooped most of the guts out of a aa to c cell adaptor. i used a stack of old 1p coins, and ran a piece of brass sheet over them to help conduction, and to provide a nipple at the top. this top stack was wedged in the body of the c cell adaptor. these coins basically extend the length of the batterys to match the length of the 3C cells. next i took another strip of the brass sheet (didnt have copper, didnt trust ally foil!) and ran a connection from the top of my first 18650, to a distance about 3mm past the negative end. the next 18650 had another strip the same size, but this ran from the negative end to 3mm past the positive. both of these strips are about 5 mm wide, and covered in electrical tape. they are only bare where they touch the batterys. i have a piece of 2mm thick foam between these strips to both help electrical isolation and to help keep the connection tight. the bottom 18650 also sits inside a gutted aa to c cell adaptor. i can easily remove the cells for charging, but because i have to slide them inside the adapters i covered them in elec tape to prevent any nasty shorting moments.


ASCI ART! :twothumbs

----------------_____________
---------------( --------------)
(111111111111(F)22222222222)
(______________)




1 is the first cell, 2 is the second, F is the foam. connecting a mulimeter to each end gives me 4.18 volts. alrighty. i did a run test in a bucket, after an hour my DIV01 was running at 3.85 volts. not amazing, about 30 percent capacity remaining. not bad for crappy old cells. torch did appear to be running at full brightness though. im happy, planet is happy. Eneloops go into the tv remote, its all win.

Im not allowed to post attachments, prob as this is my second post. if anyone is able to host the photos, i can email them to you. I have no idea if i can send/read pm yet, but i'll do my best.


any questions, let me know. this mod will work for any 3 c cell torch, so maglites and stuff i suppose. dont be shy with the elec tape!
 
Hi, and welcome to the addiction.

I mean FORUM!!!!! Welcome to the forum!!!

I've never seen anyone attempt this before. Clever solution, but it all sounds a bit risky to me. Short one of those cells and suddenly you are carrying a pipe bomb with the fuse lit! I think I'd rather see a hard insulator between the two cells, than a piece of foam.

Nobody is allowed to post attachments. You have to have the image on a third-party site like imageshack, picasa, dropbox, etc. Then you paste a link in the URL field of the 'insert image' popup. I think maybe you have to have 5 posts before you can PM.
 
Thanks for the Greets DIW. you definitely seem to know your way around the flashlights on here!

your right about the pipebomb, hopefully these pics will show you how ive insulated the parts. ive used imagur.



or here

http://imgur.com/yILYTi1



the pics show the parts, and the final result. hopefully you can see how i carved out the aa to c cell adaptor, basically i removed 2 out of the 3 internal braces. this gives enough space for a 18650, with its connector. One of the adaptors also had about 5mm of the remaining internal brace chopped off, so the stacked pennies become a very tight fit - giving me a positive pole. the cells are then stacked up, two more adaptors are slid on, then its multimetered, slid in the torch, done.

hopefully you can see that the connectors are pretty much covered in elec tape, except in the places where they meet the cell poles.

If i did this again..... id have made a note of which cells where paralled in the laptop pack, and kept them together. i should be able to charge the cells as a unit, but this way i can charge and test them individually. and if anyhting goes iffy i can also slide in those wonderful indonesian c cells ive used before...;)
 
Top